Light Pollution Beyond the Visible: Insights from People’s Perspectives

Abstract

Light pollution, most visible in large cities through the absence of star-filled night skies, has become a growing issue of concern across many disciplines. It is not just an esthetic or astronomical problem, but a complex phenomenon with widespread effects on various sectors. The scientific literature highlights several key areas impacted either directly or indirectly by light pollution: astronomy, ecology and biodiversity, the environment and climate change, human health and well-being, the ongoing energy crisis, economy, tourism, public safety and security, and finally politics. A survey was conducted to explore two main objectives. The first was to evaluate public awareness of light pollution, particularly how individuals perceive its impact across different societal sectors. The second objective was to consult lighting experts to obtain detailed insights into how severely each sector is affected by light pollution. The data collected from both the general public and lighting experts were analyzed and compared to provide a clearer picture of light pollution’s actual consequences. This dual-perspective approach aims to identify potential gaps between public perception and expert knowledge. Understanding these gaps is essential for shaping effective awareness campaigns and informing policy decisions. Ultimately, this research serves as a foundational step toward prioritizing mitigation strategies. By aligning scientific data with social understanding, stakeholders can develop targeted interventions that reduce light pollution’s negative effects while promoting sustainable lighting practices for the future.

1. Introduction

This research is guided by two complementary theoretical perspectives: environmental psychology and policy diffusion theory. Environmental psychology focuses on the dynamic interplay between individuals and their physical surroundings, offering insights into how artificial lighting affects human behavior, perception, health, and ecological awareness. It provides a valuable lens through which to examine the psychological, physiological, and social consequences of increased artificial illumination in urban environments. In parallel, policy diffusion theory helps to explain how urban lighting technologies and practices—such as the widespread adoption of LED lighting—spread across municipalities and regions, often in response to perceived benefits elsewhere rather than based on localized environmental assessments. Together, these frameworks enable a deeper understanding of both the individual and systemic forces, shaping the phenomenon of light pollution.

The rapid development of modern societies and the effects of globalization have, in recent decades, driven significant population growth in large urban centers. This urban concentration has fueled a surge in social and economic activities, creating a heightened demand for artificial lighting across cities. Research by Falchi et al. (2016) presents a world atlas of artificial sky luminance stating that more than 80% of the world and more than 99% of the U.S. and European populations live under light pollution [1]. The atlas also shows that the Milky Way is hidden from more than one-third of the world, including 60% of Europe and nearly 80% of North America [1]. Also, Tatro in 2017 states that US has wasted approximately 60 billion kilowatt hours (kWh), translating to a loss of more than $6.3 billion and CO₂ emissions [2]. Increased illumination of streets, buildings, shops, public squares, and parks has, in turn, contributed to the growing problem of light pollution. Key concerns such as crime prevention, vandalism reduction, and the need for greater public safety have played a major role in the expansion of nighttime lighting [3,4]. At the same time, artificial lighting has been widely adopted for commercial and esthetic purposes—illuminating building facades, signage, businesses, and landmarks. These lighting practices are often intended to enhance visual appeal, support branding and advertising efforts, promote tourism and local economic development [5]. As overall ambient light levels have risen in urban areas, there has been a parallel need to increase the brightness of adjacent public spaces, including pavements, parks, and pedestrian pathways, to maintain visibility and perceived safety. This escalating cycle of lighting expansion has significantly intensified the phenomenon of light pollution, prompting growing concerns about its environmental, health, and societal impacts.

Light pollution is a growing environmental issue, primarily caused by the excessive and poorly designed use of artificial lighting in urban areas. It is most prominent in developed cities and is often recognized by the lack of visible starry skies. According to the International Dark-Sky Association, light pollution stems from four key factors: glare, skyglow, light clutter, and light trespass [6]. Another contributing factor is over-illumination—the unnecessary or excessive use of light in public and private spaces. Scientific research has shown that these elements have significant negative effects on both the environment and human health. Light pollution (i) eliminates natural darkness by producing intense skyglow, (ii) disrupts daily life both indoors and outdoors, (iii) harms ecosystems and biodiversity, and (iv) interferes with the biological rhythms of living organisms, potentially impacting human development and the global supply chain.

Environmental psychology helps conceptualize these impacts by emphasizing how lighting affects circadian rhythms, sleep quality, and psychological well-being, while also mediating individuals’ sense of security and orientation in urban space. Policy diffusion theory, meanwhile, provides a framework for understanding how lighting practices—once normalized in one city—are often replicated in others without full consideration of local conditions or long-term sustainability.

At the same time, research indicates that the amount of pollution depends largely on the spectral characteristics of the lamps, with low-pressure sodium lamps being the most environmentally friendly, followed by high-pressure sodium lamps. The most polluting lamps are those with strong blue emissions, such as metal halide lamps and white LED lamps [7,8]. The rise in LED technology, praised for its energy efficiency and cost-effectiveness in outdoor lighting, has unintentionally worsened the problem. While LEDs were adopted as a sustainable solution, their widespread and often uncontrolled use has led to increased light intensity in areas where it was previously unnecessary [9,10]. Moreover, the high blue-light content in early LEDs—used extensively in various applications over the past decade—has amplified the spread of light pollution [11,12]. Over the past few decades, light pollution has increasingly affected all aspects of human activity and the natural world, and this trend will likely continue if not addressed [13]. Numerous studies have been conducted to better understand the issue and explore mitigation strategies [14,15,16]. Research has focused on applications such as road lighting, building facades, stadiums and other outdoor venues, parks, and public squares, while also addressing the importance of effective energy management in exterior lighting systems [4,17,18,19,20,21]. Despite its growing significance, light pollution remains a largely unrecognized issue, and public awareness is still insufficient. From the standpoint of environmental psychology, this lack of awareness limits individuals’ motivation to adopt corrective behaviors. In terms of policy diffusion, it reflects a failure of institutional learning and communication, as the adoption of new technologies often outpaces public education or regulatory adaptation. Given the broad impacts of this phenomenon, it is crucial that individuals and communities take informed action to help reduce its effects.

However, according to the existing literature, there has been not very extensive investigation into public perception regarding the phenomenon of light pollution. An online survey conducted in 2013 by Lyytimäki and Rinne aimed to document how the public perceives this issue. The findings indicate that the ecological and health-related impacts of light pollution—emphasized by the research—remain largely unknown to the public, who tend to focus primarily on its esthetic aspects [22]. However, a study by Bashiri and Hassan (2014) show that if questions to the general public are specific and focused on the subject matter, people understand the influence of light pollution into their lives [23].

In addition, a study by Zielinska-Dabkowska et al., in 2020, presents a significant number of legal actions initiated by dating back to the 1920s—most of which have taken place in the United States [24]. There has also been a rise in online petitions addressing light pollution, starting in 2013 and continuing to the present day [24]. This research proposes a seven-step framework that includes recommendations for citizen engagement. This framework aims to empower planning, implementation, and monitoring of outdoor lighting by providing people with actionable knowledge.

The present research sets out with a twofold aim. First, it seeks to identify and clarify the various sectors affected by light pollution through a comprehensive review of the existing scientific literature. Secondly, it uses a structured questionnaire to investigate two key areas: (i) the level of public awareness and understanding of light pollution, and (ii) how experts and professionals in the field perceive the problem, including which sectors they believe are mostly affected. By comparing public perception with expert’s opinion, this study aims to bridge the knowledge gap and highlight areas where awareness must be improved.

The integration of the two theoretical frameworks, allows for a more robust interpretation of the findings. Through environmental psychology, the study explores how individuals experience and respond to artificial lighting in urban contexts. Through policy diffusion theory, it examines how decisions about lighting technologies and regulations are formed and propagated. The goal is to establish clear priorities for mitigation efforts, focusing on the sectors where interventions would be most effective. Through this approach, the research contributes to a better understanding of light pollution’s real-world consequences and supports the development of targeted strategies to reduce its impact.

While much of the existing literature has focused on the technical, ecological, or astronomical impacts of artificial lighting, this research uniquely emphasizes the psychosocial dimensions of light pollution alongside the institutional mechanisms through which lighting practices spread. By comparing public perception with expert’s opinion, the study identifies critical gaps in knowledge and understanding that hinder effective mitigation, and this offers a novel contribution to the field of light pollution research. The research’s originality lies in its dual-method approach: it combines a systematic literature review with empirical data gathered through a structured survey targeting both the general public and lighting experts (professionals, academics, etc.) in the field. This enables a rare comparative analysis that not only maps the sectors mostly affected by light pollution but also reveals perceptual discrepancies that may inform future education, communication, and policy strategies. Ultimately, this study contributes to the existing body of knowledge by broadening the conceptual scope of light pollution research beyond technical solutions, highlighting the role of human perception, institutional behavior and public engagement in shaping lighting practices and their environmental consequences.

1.1. Sectors

This section outlines all sectors impacted by the phenomenon, as identified in the existing scientific literature. The following analysis reveals significant overlap among these sectors, with some elements intersecting or appearing within multiple areas.

1.1.1. Astronomy

One of the earliest relevant reports on light pollution and its effects on astronomy, was made by Riegel in 1973, stating that is caused by two main reasons: (a) the increase in cities’ population and (b) the increase in external illumination of urban centers [25]. The improper application of lighting design in outdoor spaces, coupled with rising light levels, contributes to glare, light trespass, and visual clutter—factors that collectively create a skyglow over urban areas, obstructing the visibility of starry skies. Additionally, the recent surge in air traffic and the growing demand for orbital space due to microsatellite deployment have intensified a newer challenge known as Visual Light Pollution (VLP) [26]. These factors hinder the observation and monitoring of celestial bodies, an activity crucial for planetary research and environmental protection [27]. As a result, many observatories—often located in remote or semi-rural areas near cities—are being forced to relocate, as their original sites no longer offer the dark-sky conditions required for effective operation [28]. This shift poses a significant loss not only to the field of astronomy but also to education and tourism. Schools and tourists frequently visit these observatories to engage with the cosmos through expert-led stargazing experiences [29,30]. To address these challenges, specialized lighting strategies are essential in areas surrounding observatories. Such designs aim to minimize light pollution and enhance the visibility of stars. In response, a set of guidelines has been proposed to optimize lighting near observatories, helping to protect dark skies and support both scientific and public appreciation of the night sky [28].

1.1.2. Ecology and Biodiversity

Another sector where light pollution has demonstrated a significant and concerning impact is ecology and biodiversity. Artificial outdoor lighting disrupts the natural balance of ecosystems, affecting both plant and animal life. Many species rely on the Earth’s natural cycle of light and darkness to regulate vital behaviors such as reproduction, feeding, sleeping, migration, orientation, and protection from predators [31]. Extensive research has been conducted on the effects of artificial light on a wide range of organisms, including birds and terrestrial animals [31,32], marine and coastal ecosystems—such as sandy and rocky shores, coral reefs, and pelagic zones—as well as specific species like sea turtles and seabirds [33,34]. These studies span various habitats including lakes, oceans, and shorelines [35]. In recent years, a noticeable decline in animal populations has been observed, particularly among species sensitive to changes in nighttime illumination. Nocturnal creatures such as bats have been severely affected [36]. Diurnal predators are increasingly extending their hunting into nighttime hours, while amphibians that rely on dark conditions for breeding, and sea turtles that hatch on beaches, are facing growing challenges due to bright artificial lights [37]. Migratory birds, too, are often disoriented by artificial lighting, causing them to stray from their migratory paths [34]. These disruptions, caused by excessive artificial lighting at night, interfere with the natural behaviors of countless species and threaten the delicate balance of ecosystems, ultimately hindering biodiversity and the long-term health of the environment.

1.1.3. Environment and Climate Change

In recent decades, as a significant portion of the global population has migrated to urban centers, the microclimate and overall climate of these areas have begun to shift. The concentration of people in cities has brought about a corresponding concentration of both indoor and outdoor activities, leading to a dramatic increase in artificial lighting—often in areas that were previously dark. This surge in illumination was driven by the need to support social and economic activity, enhance public safety, and accommodate urban lifestyles. The advent of LED technology has further accelerated the spread of artificial lighting, making it more affordable and efficient. However, this has also contributed to its overuse, particularly in the architectural highlighting of landmarks and cityscapes aiming at expressing identity and economic status. As a result, public energy consumption has soared, while light pollution has been intensified—contributing not only to visual disruption but also to atmospheric and broader environmental degradation [38,39]. The relationship between air quality and light pollution has also been proven that where the aerosol particle size distribution and chemical composition significantly affect light scattering efficiency, thereby influencing light pollution [40,41]. As previously discussed, this phenomenon has profound ecological consequences. Excessive nighttime lighting disrupts biodiversity, affecting both flora and fauna. Natural behaviors are altered, food chains are disturbed, and the availability of natural resources on land have strained [39]. The combination of climate change and intensified skyglow interferes with ecosystem functions, often leading to species’ disorientation, breakdowns in food webs, and, in some cases, extinction [42]. Despite ongoing efforts to mitigate light pollution, current measures have proven insufficient. The challenge now lies in implementing more effective, sustainable strategies that balance the needs of urban development with the preservation of ecological health and environmental integrity.

1.1.4. Human Health and Well-Being

Another area significantly affected by light pollution is human health and well-being. In order for the human biological clock to function optimally—both physically and psychologically—it must follow a natural 24 h cycle of alternating light and darkness. Exposure to artificial light at night (ALAN) disrupts this rhythm, particularly by interfering with the production of melatonin, a hormone crucial for regulating sleep and maintaining bodily balance [43]. When melatonin secretion is suppressed, it can lead to a range of health issues. ALAN, especially prevalent in densely populated urban environments, has been linked to a variety of negative health outcomes including obesity, sleep disorders, mood swings, depression, diabetes, certain types of cancer, altered cortisol levels and cardiovascular diseases [44,45,46]. Factors contributing to these effects such as light trespass—where poorly designed outdoor lighting spills into indoor spaces—are disrupting circadian rhythms even inside the home. Another major concern is glare, which results from the direct visibility of light sources or excessive illumination. Glare not only reduces the ability to see clearly at night, but also contributes to eye strain, fatigue, and, over time, potential vision damage [47,48]. Moreover, it can impair nighttime driving by reducing contrast sensitivity and reaction times, increasing the risk of accidents [49]. The widespread adoption of LED lighting in recent years has further intensified the problem. While energy-efficient, many LEDs emit high-intensity light with a strong blue wavelength component, which has been shown to suppress melatonin production more effectively than other types of light [43]. Additionally, the growing use of screen-based media devices (SBMDs)—especially at night and in dark environments—exacerbates sleep disturbances and negatively impacts overall quality of life [50]. These factors, altogether, illustrate how pervasive artificial lighting is, if left unchecked, posing a serious threat not just to environmental balance, but to human health and well-being as well.

1.1.5. Energy Crisis

The advancement of LED technology has brought significant changes to outdoor lighting, allowing authorities to upgrade their lighting infrastructures with more energy-efficient systems. While this transition was intended to reduce energy consumption, it has, in many cases, produced the opposite effect. As researchers have noted, “when light becomes cheaper, many users will increase illumination, and some previously unlit areas may become lit” [12]. This phenomenon—often referred to as the rebound effect—has contributed to a rise in overall light use. Outdoor lighting is estimated to account for 15–19% of global electricity consumption. In total, lighting represents approximately 2.4% of humanity’s annual energy use and is responsible for 5–6% of global greenhouse gas emissions [51], further intensifying environmental challenges. According to the International Energy Agency, cities consume nearly 75% of global energy, with outdoor urban lighting alone contributing to 20–40% of municipal energy budgets [52]. Although the immediate effects of the global energy crisis began to ease in 2023, the risk of future disruptions remains high [53]. Beyond operational energy use, the mass production and installation of new lighting fixtures to replace outdated systems place a heavy burden on both the manufacturing sector and the environment. This process generates significant carbon emissions and increases the demand for energy-intensive recycling, adding further strain on already overtaxed environmental systems. Given these challenges, sustainable lighting practices are becoming increasingly essential. Thoughtful lighting design that emphasizes the use of light only where and when it is truly needed is critical. Moreover, as societies transition toward cleaner sources of energy, it is becoming clear that simply producing more energy is not a long-term solution. Without addressing the underlying issue of excessive consumption, the environmental benefits of clean energy may be offset. A more strategic, responsible approach to lighting is necessary to ensure that energy efficiency does not come at the cost of environmental sustainability [53].

1.1.6. Economy

The excessive use of outdoor lighting not only contributes to high levels of light pollution but also places a significant financial burden on municipalities. As already mentioned [52], cities consume nearly 75% of the world’s energy, with outdoor urban lighting alone accounting for up to 20–40% of municipal energy-related expenditures. Therefore, governments spend billions of dollars/euros annually on outdoor lighting—costs that are, in many cases, unnecessary and avoidable. This financial strain is directly linked to inefficient lighting practices, where light is used excessively or in areas where it is not needed. Light pollution and the associated energy consumption are not just environmental issues—they are also economic concerns. By strategically reducing unnecessary lighting, cities and municipalities can achieve substantial savings while also benefiting the environment and public health. In addition to the direct costs, several other sectors are indirectly affected by light pollution, resulting in broader economic impacts. One such sector is astrotourism. Skyglow from urban lighting obscures the night sky, making it difficult for observatories to operate effectively and deterring tourists who would otherwise visit these areas to experience stargazing. This loss of tourism revenue can significantly affect local economies, especially in rural or remote regions that rely on such attractions. Another area of concern is public health. The negative effects of light pollution on human health—ranging from sleep disorders to increased risks of chronic illnesses—can lead to rising healthcare costs. These health impacts place an indirect but substantial financial burden on public health systems and, by extension, on governmental budgets [38]. Ultimately, addressing light pollution and promoting responsible lighting practices is not just a matter of protecting the environment—it is a strategic investment in economic sustainability, public health, and the long-term well-being of communities.

1.1.7. Tourism

When it comes to tourism, the literature reveals two contrasting trends influenced by light pollution. The first trend involves tourism focused on natural experiences, such as stargazing and visits to protected wildlife areas. These destinations require minimal artificial lighting to preserve their natural character and ecological balance. Excessive light in such areas can cause serious disruptions [54]. As discussed in Section 1.1.1, observatories located near urban centers often struggle with the effects of light pollution, which forces them to relocate to more rural regions. This not only hinders astronomical research but also reduces opportunities for astrotourism and educational programs. To support these activities, the preservation of dark skies and the implementation of light-reduction policies are essential [55]. Similarly, protected natural areas rely on low-light environments to sustain the delicate ecosystems they host. Wildlife in these areas depends on natural darkness for behaviors such as mating, foraging, and navigation. However, the pressures of growing tourism and expanding urban development can disrupt these patterns, threatening biodiversity and the long-term viability of conservation efforts [56,57]. The second trend in tourism highlights the opposite issue—regions where increasing visitor numbers have led to rising levels of light pollution. A study by Democritus University focusing on Greece notes that tourist destinations, including major Greek islands and other popular areas, are experiencing a surge in artificial lighting due to their growing appeal [58]. These areas often use bright lighting to enhance esthetics, promote nightlife, and increase perceived safety, all of which contribute to the worsening of the phenomenon. Together, these two tourism-driven dynamics illustrate the complex relationship between lighting, environmental preservation, and economic development. While one form of tourism suffers from too much light, the other inadvertently contributes to it—highlighting the urgent need for sustainable lighting strategies that balance both environmental integrity and tourist experience.

1.1.8. Safety and Security

As urban centers’ population has encouraged rapid growth, the demand for enhanced lighting in public spaces—such as parking lots, streets, parks, and squares—has grown, primarily driven by concerns over safety and the protection of citizens [59]. In response, many cities have implemented extensive lighting installations, often using energy-efficient LED technology. While these measures aim to improve visibility and security, they also result in significantly elevated light levels across urban environments. These forms of poor lighting not only contribute to light pollution but also reduce the overall quality and effectiveness of lighting itself [49]. Rather than enhancing safety, such lighting often creates a false sense of security and may, in fact, introduce new risks. Excessive brightness and misdirected lighting can cause visual discomfort, disorientation, and even increase the likelihood of accidents, particularly for drivers and pedestrians [60]. Ultimately, the key lies in thoughtful, well-designed lighting that balances the need for safety with environmental sustainability and human comfort. Properly implemented lighting installations can enhance public spaces without compromising health, visibility, or ecological integrity.

1.1.9. Politics

Based on the above, it is evident that light pollution is closely linked to politics as well, as efforts to regulate, manage, and mitigate the issue largely depend on governmental action [57]. Public policy, national regulations, and local ordinances play a critical role in shaping how lighting is implemented and controlled in both urban and rural areas. Some countries and cities have taken more proactive steps than others by enforcing stricter lighting regulations aimed at minimizing light pollution. Notable examples include Tucson in the United States and the country of Slovenia, both of which have implemented comprehensive policies to preserve dark skies and reduce unnecessary artificial light [61,62]. In addition, Schuler’s research focuses on the investigation of the Suomi NPP (Suomi National Polar-orbiting Partnership) satellite in night vision to investigate the impact of road illumination on light pollution, public and road safety, and also crayfish habitats in the Canton of Zurich against local illumination for the city of Zurich [57].

These policy choices reflect not only the political will of each government, but also the level of awareness and prioritization of the issue within each region. However, despite growing international collaboration and policy initiatives to address light pollution, a significant gap in understanding and awareness remains. As highlighted by the International Energy Agency (IEA), many policymakers and communities still underestimate the risks and wide-ranging consequences associated with light pollution—from environmental and health impacts to energy waste and economic costs [57]. This underscores the need for stronger public education, international cooperation, and more consistent regulatory frameworks to effectively combat the growing threat of light pollution on a global scale.

2. Materials and Methods

As the phenomenon of light pollution spreads through the years, its influence on various areas of human activity in developed societies is considerable. According to scientific bibliography, the main areas affected from the phenomenon are astronomy [25], ecology and biodiversity [63], environment and climate change [64], human health and well-being [43]. However, there are additional sectors that are also affected, and these are energy crisis, economy, tourism, safety and security, and politics.

As previously mentioned, this research serves a dual purpose (Figure 1). First, it aims to explore the awareness of light pollution and its societal consequences among the general population in developing societies, specifically those who are neither professionally nor informally engaged with lighting, who will be called as “Public perception”. Second, it focuses on experts in the field of lighting, which include both lighting design professionals, such as lighting designers, lighting industry professionals, consultants and academics, researchers, etc., who will be called as “Experts”. Experts are asked to present through their expertise how light pollution impacts various key areas and to what extent these are affected. For the purposes of this research, a global survey was designed and distributed via social media, online survey platforms, digital channels, lighting designers’ and academic networks [65].

The use of social media and digital platforms for survey distribution does introduce a potential bias toward more tech-savvy or environmentally aware individuals, a limitation we acknowledge. However, in today’s digital age, online data collection offers practical advantages in terms of speed, reach, and accessibility. Notably, the survey did attract participation from individuals living in non-urban areas, whose responses provided valuable and often underrepresented perspectives. These insights help balance the dataset and enrich the analysis by incorporating views from a broader demographic spectrum. Future research could benefit from stratifying responses by factors such as urban versus rural residence to further address this limitation and enhance the representativeness of the findings.

The first findings of the study were presented by Skandali et al. in 2024 [13], which examined public perception on light pollution. This initial study has revealed a noticeable gap in awareness and understanding of light pollution among the general population. Building on those insights, the current survey—presented in this paper—focuses on the sectors most affected by light pollution and gathers input from both experts and public perception. This approach enables a comparative analysis of perspectives, allowing for meaningful cross-referencing of the results and the development of well-rounded conclusions.

An in-depth survey was conducted with the primary objective of enhancing public awareness of light pollution, particularly focusing on the impact it has across the nine areas previously highlighted. The survey aimed not only to broaden citizens’ understanding of this pressing environmental issue but also to gauge the prevailing perceptions regarding its effects.

The survey was structured using Google Forms and consisted of two key sections [65]. The first section was exploratory, designed to assess the participants’ familiarity with the concept of light pollution, including its causes and consequences on both the environment and human health. This section of the survey asked participants to rate, with a six-point Likert-type scale ranging, from 0 to 5 (0—no harm, 1—very little harm, 2—little harm, 3—medium harm, 4—much harm, 5—very much harm) how much they believe that each sector studied is burdened by the phenomenon of light pollution [66]. There is a debate about the appropriate statistical treatment of Likert scale data [67,68], as the scale suggests an order but not necessarily equal intervals between responses. However, many researchers treat it as a graduated scale, and it has been widely used in surveys on socio-cultural and environmental valuation [69,70]. The second section delved deeper into the specific subject matter of this publication, asking all participants (both experts’ opinion and public perception) to define key terms related to various dimensions of light pollution, as outlined in the previous sections. To capture a diverse range of perspectives, the survey was disseminated globally via social media platforms and survey websites. The target audience included individuals from various backgrounds, both within and outside the lighting industry, to ensure a comprehensive understanding of the level of awareness surrounding this issue. By engaging people who are either familiar or non-familiar with the subject, the survey aimed to reveal broader public perception and knowledge gaps regarding light pollution.

Over a span of three months, the survey gathered a total of 230 responses, from 32 different countries, with the majority of participants (64%) hailing from Europe as presented in Figure 2. Respondents were assured anonymity, fostering an environment where they could answer candidly. Following the data collection, the responses were meticulously analyzed, yielding intriguing insights that are presented below. To ensure the reliability of the findings, a 7% margin of error was applied, with a 90% confidence level in the participants’ responses [71]. The first question posed to participants asked whether they were familiar with the concept of light pollution. Only 32.61% of respondents indicated that they were familiar with the term and all of them have an academic background in the lighting field and/or are lighting design professionals, so they can also be referred to as experts, while the remaining 67.39% expressed a lack of familiarity, either responding with “no”, “don’t know”, or “not sure” (public perception). These responses were collectively categorized as negative, highlighting a significant gap in awareness about light pollution among the general population (Figure 3). However, despite their negative response to these issues, in general, their further participation in the survey process shows that this gap can possibly be filled in part either by common sense or by specific knowledge in certain sectors (Figure 4).

This initial finding underscores the need for continued education and outreach to bridge the knowledge gap surrounding the environmental and societal implications of light pollution.

The responses collected through the first section of the survey serve two main purposes. The first is to quantify each respondent’s level of concern. To achieve this, the average of all scores assigned to each sector is calculated, and a variable named Total Concern (TC) is constructed to support the subsequent analysis. The second goal is to identify distinct factors of concern among respondents by grouping the sectors considered in this study into broader categories. This aims to enhance our understanding of respondents’ primary concerns and facilitate future research on the topic.

To construct these distinct factors from sector scores, Principal Components Analysis (PCA) with Varimax Rotation is applied. PCA reduces and organizes variation among variables to simplify and explain patterns in the data. Reliability is first assessed using Cronbach’s α; PCA is only conducted when α is approximately 0.70 or higher [73], which may require the removal of items that reduce internal consistency. The adequacy of PCA is then evaluated using the Kaiser–Meyer–Olkin (KMO) measure—where values above 0.50 indicate sufficient shared variance—and Bartlett’s test of sphericity, which must reject the null hypothesis of no correlation among variables for PCA to proceed [74].

The differences in perceptions between experts and non-experts are examined in two stages. First, analysis is conducted on the total concern scores. To assess potential differences in concern levels between the two groups, a regression model with an Ordinary Least Squares (OLS) specification is employed. In the second stage, average scores within each factor extracted through PCA are calculated, followed by t-tests to determine whether there are significant differences in mean concern levels between experts and non-experts [75].

Expertise is operationalized using a dummy variable (Exp), coded as 0 for non-experts and 1 for experts. For the regression analysis on total concern scores, beyond the basic model specification, additional control variables are included in extended models to account for potential heterogeneity in concern levels due to other factors. These control variables are listed in

Table 1. The control variables of the analysis.

Control Variable	Description
Gen	A dummy variable quantifying gender. Takes 0 for Males and 1 for Females.
Age	A variable quantifying age. The variable takes the following values according to the age interval each respondent declared in the survey. 1. 18–27, 2. 28–43, 3. 44–59, 4. ≥60
Edu	A variable quantifying the highest education level completed by each respondent. The variable takes the following values according to the age interval each respondent declared in the survey. 1. Secondary Education, 2. University Diploma, 3. Master or PhD
SQM	The variable is based on Sky Quality Meter (SQM) readings corresponding to the city each respondent identified as their place of residence. It represents night sky brightness, measured in magnitudes per arcsecond squared (mag/arcsec2), with higher values indicating darker skies and thus lower levels of light pollution. The variable ranges from 14 to 23. When SQM data was reported as an interval for a given city, the midpoint of the range was used. This variable is included in the analysis to account for the potential effect of the respondent’s current light environment on their level of concern about light pollution. Data was retrieved from [72,76].
Bright	This variable represents the average brightness per square kilometer, indicating the intensity of light pollution across a given area. It is estimated at the national level and is used to account for potential heterogeneity in respondents’ concern that may arise from differences in the light environment between countries in the sample [72,76].
Eur_Dum, Asia_Dum, Austr_Dum	These are dummies accounting for the continent of the respondents (Europe, Asia, Australia). The dummies are incorporated into the model with the reference continent being America (It should be noted that no respondent from Africa is included in the sample).

Source: Own elaboration.

.

The final specification of the full model is the following:

$$\begin{array}{l}{TC}_i={\beta }_0+{\beta }_{Exp}\ast {Exp}_i+{\beta }_{Gen}\ast {Gen}_i+{\beta }_{Age}\ast {Age}_i+{\beta }_{Edu}\ast {Edu}_i+{\beta }_{Gen}\ast {Gen}_i\\ \hspace{1em}\hspace{1em}\hspace{1em}\hspace{1em}\hspace{1em}\hspace{1em}+{\beta }_{SQM}\ast {SQM}_i+{\beta }_{Bright}\ast {Bright}_i+{\beta }_{Eur\_Dum}\ast {Eur\_dum}_i\\ \hspace{1em}\hspace{1em}\hspace{1em}\hspace{1em}\hspace{1em}\hspace{1em}+{\beta }_{Asia\_Dum}\ast {Asia\_dum}_i+{\beta }_{Aust\_Dum}\ast {Aust\_dum}_i\end{array}$$

(1)

3. Results

3.1. Analysis on Concern

The main descriptive statistics for the variables included in the analysis of expert and non-expert views are presented in

Table 2. Descriptive statistics of the variables.

Variable	N	Min.	Max.	Average	Std. Dev.
Exp	235	0.00	1.00	0.33	0.47
Gen	235	0.00	1.00	0.59	0.49
Age	235	0.00	4.00	2.10	0.86
Edu	235	1.00	3.00	2.46	0.69
SQM	177	17.25	21.00	18.80	0.75
Bright	235	0.04	12,894.00	910.31	1101.19
Economy	235	0.00	5.00	2.39	1.57
Astronomy	235	0.00	5.00	3.36	1.65
Politics	235	0.00	5.00	1.38	1.36
Human health and well-being	235	0.00	5.00	3.57	1.35
Ecology and biodiversity	235	0.00	5.00	3.86	1.29
Environment and climate change	235	0.00	5.00	3.50	1.50
Tourism	235	0.00	5.00	2.19	1.36
Safety and security	235	0.00	5.00	2.11	1.50
Energy crisis	235	0.00	5.00	3.38	1.50
TC	235	0.20	4.80	2.82	0.90

Source: Own Elaboration.

. As shown, 33% of respondents are classified as experts, and 59% are female. Regarding age, the average respondent falls within the 44–59 age range, and the majority hold either a Master’s or PhD degree. The average Sky Quality Meter (SQM) value is 18.80, indicating moderate night sky brightness in respondents’ cities. The national-level light pollution variable (RAD) has an average of 910.31, with a standard deviation exceeding the mean, suggesting considerable variability across countries in the sample. Among the sectors assessed, the highest level of concern is reported for ecology and biodiversity, while the lowest is for political impacts. Finally, the average total level of concern (TC) is 2.82, reflecting a modest overall concern about the impacts of light pollution.

Th results of the regression analysis and estimated coefficient are presented in

Table 3. The estimated coefficients of the different specifications and the basic diagnostics of fit per model.

Categories	Coefficient	Models
		1	2	3
	${\mathrm{\beta }}_{\mathrm{E}\mathrm{x}\mathrm{p}}$	0.392 ***	0.459 ***	0.481 ***
Demographics	${\mathrm{\beta }}_{\mathrm{G}\mathrm{e}\mathrm{n}}$	0.399 ***	0.43 ***	0.418 ***
	${\mathrm{\beta }}_{\mathrm{A}\mathrm{g}\mathrm{e}}$	0.089	0.126 *	0.106
	${\mathrm{\beta }}_{\mathrm{E}\mathrm{d}\mathrm{u}}$	0.46 ***	0.437 ***	0.424 ***
Light Environment	${\mathrm{\beta }}_{\mathrm{S}\mathrm{Q}\mathrm{M}}$		−0.18 **	−0.185 **
	${\mathrm{\beta }}_{\mathrm{B}\mathrm{r}\mathrm{i}\mathrm{g}\mathrm{h}\mathrm{t}}$		4.86 × 10−5	3.54 × 10−5
Geography	${\mathrm{\beta }}_{\mathrm{E}\mathrm{u}\mathrm{r}\_\mathrm{D}\mathrm{u}\mathrm{m}}$			0.158
	${\mathrm{\beta }}_{\mathrm{A}\mathrm{s}\mathrm{i}\mathrm{a}\_\mathrm{D}\mathrm{u}\mathrm{m}}$			0.078
	${\mathrm{\beta }}_{\mathrm{A}\mathrm{u}\mathrm{s}\mathrm{t}\_\mathrm{D}\mathrm{u}\mathrm{m}}$			−0.01
	${\mathrm{\beta }}_0$	1.137 ***	4.452 ***	4.499 ***
Model Info
	Adj R2	0.195	0.279	0.267
	F	15.141 ***	12.343 ***	8.128 ***
	N	235	177	177

Notes: Statistical Significance Levels: *** (<0.01), ** (<0.05), * (<0.1).

. The Adj. R² value ranges from 0.195 to 0.267 with models of richer number of controls coming up with higher R² values. The signs of the estimated coefficients remain the same across all model specifications, and only some minor variations in the statistical significance of the coefficients of the Age variable are observed. The F statistic, a measure of the overall explanatory power of the models, was found to be statistically significant at the (<0.01) level for all specifications.

Regarding the main variable of interest—Exp—the estimated coefficient remains positive and statistically significant at the 1% level across all three models. This finding indicates that higher expertise is associated with greater concern about the impacts of light pollution. The consistency of this result across all model specifications suggests that the effect of expertise remains robust regardless of demographic, environmental, or geographical conditions.

Examining the control variables, we find that females express significantly higher levels of concern compared to males, and that concern increases with the level of education. The relationship between age and concern appears weak; the age coefficient is statistically significant in only one model, and only at the 10% level.

The local light environment also appears to influence concern levels. Specifically, the coefficient for the SQM variable is negative and statistically significant at the 5% level. Since higher SQM values indicate darker skies (i.e., less light pollution), this result suggests that individuals living in less polluted areas report lower levels of concern about light pollution. In contrast, the national-level brightness variable (RAD) does not have a statistically significant effect on concern. However, this result should be interpreted with caution, as the variable captures national averages rather than local conditions. Finally, the continent dummy variables are not statistically significant, indicating that there are no substantial regional differences in concern about light pollution across different parts of the world.

The second part of the quantitative analysis explores sector-specific concern levels to determine whether patterns found in the PCA hold across individual sectors. These results are presented in

Table 4. Factors of concern about the impacts of light pollution.

Factors/Items	Factor Loadings	Explained Variance (%)	Cronbach’s Alpha	Mean	St.Dev
Environmental/Well-Being Concerns		35.05	0.73	3.53	1.14
Ecology and biodiversity	0.907
Human health and well-being	0.822
Environment and climate change	0.737
Energy crisis	0.643
Astronomy	0.627
Socio-Economic Concerns		26.73	0.84	2.02	1.08
Politics	0.849
Economy	0.761
Safety and security	0.672
Tourism	0.486
Statistical tests
Kaiser–Meyer–Olkin Measure of Sampling Adequacy.	0.83
Bartlett’s Test of Sphericity	938.76	D.f.: 36	Sig. < 0.001

.

PCA returned two factors with eigenvalues exceeding the critical value of 1, together explaining over 61% of the total variance. The Cronbach’s α for the items associated with both factors exceeded the commonly accepted threshold of 0.70, indicating satisfactory internal consistency. The Kaiser–Meyer–Olkin (KMO) Measure of Sampling Adequacy also surpassed the critical value of 0.50, supporting the suitability of the data for factor analysis. Furthermore, Bartlett’s Test of Sphericity yielded a statistically significant result at the 1% level (p < 0.01), confirming sufficient inter-item correlation to proceed with the analysis.

The first factor, which explains the majority of the variance, is shaped by sectors capturing the environmental impacts of light pollution. The highest factor loadings are observed for ecology and biodiversity, health and well-being, and environment and climate change. The second factor consists of sectors related to socioeconomic dimensions, such as politics and the economy.

To assess whether there are differences in concern levels between experts and non-experts for these two factors, t-tests for equality of means were conducted, accompanied by mean error bar plots (Figure 5). The results indicate a statistically significant difference between the two groups only for Factor 1. Specifically, the analysis returned to a t-value of −2.857 (degrees of freedom: 233, p < 0.01), indicating that the mean difference of 0.42 between experts and non-experts is statistically significant. In contrast, no significant difference was found for Factor 2, suggesting that experts and non-experts express similar levels of concern regarding the socioeconomic impacts of light pollution. This distinction is further supported by the non-overlapping error bars observed only for the first factor.

3.2. Analysis on Sectors

The survey results reveal meaningful differences and similarities in how light pollution is perceived by those familiar and non-familiar with the topic. Both groups identified ecology and biodiversity, human health and well-being, and astronomy as the most affected sectors, although experts consistently rated these impacts slightly higher. This suggests a general consensus on the most visible consequences of light pollution, with experts having a deeper understanding of its scope. Ecology and biodiversity received the highest average score (3.85 out of 5), reflecting widespread concern over how artificial lighting disrupts natural habitats and wildlife behavior. Astronomy followed closely, particularly among experts (3.63), who are more attuned to the effects of skyglow and glare on observation conditions. Human health and well-being were also rated highly, indicating growing recognition of how artificial light interferes with sleep patterns and circadian rhythms.

However, there were notable gaps in how public perception evaluated certain sectors. For instance, the energy crisis was rated significantly higher by experts (3.62 compared to 3.21), indicating that the general public may not fully grasp how over-illumination contributes to unnecessary energy consumption and climate concerns. Public safety and security were given a lower rate by public perception (2.01), compared to the experts’ assessment (2.29), hinting at a prevailing belief that more light equates to greater safety—despite evidence that excessive lighting can have the opposite effect. Both groups gave low ratings to economy, tourism and politics, with politics receiving the lowest score overall. Both experts and public perception seem to believe that the sectors related to the environment, ecology, health, astronomy, energy crisis and security are more affected by the phenomenon, without of course suggesting that light pollution does not widely seen asaffect the economy, tourism and politics, but perhaps to a lower extent. The low score for politics reflects that the issue has not yet gained sufficient visibility or priority in the political agenda, despite the need for regulatory frameworks, sustainable urban planning, and broader public discourse. These findings highlight the need for informed political engagement that bridges the gap between policy inaction and public concern.

Overall, experts view the effects of light pollution as more serious across nearly all sectors, reinforcing the need to raise public awareness. Experts tend to prioritize the energy crisis, whereas less experienced individuals (public perception) are more focused on environmental and climate change issues. This difference may stem from experts viewing light pollution as a problem that can be addressed more rapidly and easily—such as by simply turning off lights—compared to the long-term and complex challenge of reducing CO₂ emissions [38]. The findings highlight a clear need for educational efforts to close the knowledge gap and suggest that policy and mitigation strategies should focus not only on well-known sectors like ecology and health but also on underappreciated areas such as energy, tourism, and safety.

The detailed results of all responses concerning the factors affecting light pollution are presented below. These have been divided into the two super-factors presented above (Table 4) and relate to Environmental/Well-Being Concerns and Socio-economic Concerns. The diagrams below show the keywords used by the survey participants and the percentages of the most frequent choices. For the final formatting of the keywords, some responses that were formulated with different words but had the same meaning were incorporated into a common keyword in order to make the presentation of the research more understandable.

3.3. Analysis of Sectors Related to Environmental/Well-Being Concerns

3.3.1. Ecology and Biodiversity

Expanding further on the comparison between the two groups, key differences are revealed in perception, depth of understanding, and specificity in recognizing how light pollution affects ecology and biodiversity (Figure 6). To begin with, both groups agree that the most significant impact of light pollution lies in ecosystem disruption and biodiversity loss. However, the degree to which they emphasize this issue differs. Public perception places a heavier weight on this category, with nearly half (48.15%) identifying it as the primary issue, compared to 40.82% of experts. This suggests that while public perception is generally aware that light pollution has ecological consequences, their understanding remains largely conceptual or generalized. They (non-experts) are more likely to frame the problem in broad terms like “ecosystem disruption” without detailing the pathways or species involved. Experts, on the other hand, distribute their responses more evenly across a wider set of ecological issues, indicating a deeper and more segmented understanding. For instance, experts mention wildlife impacts (28.57%) and effects on nocturnal species (22.45%) at notably higher rates than non-experts, who mention these at 20.37% and 14.81%, respectively. This difference indicates the more specialized knowledge of experts regarding the individual impacts of the phenomenon on ecology and biodiversity—such as altered predator-prey dynamics, disrupted reproductive cycles, or migration path interference in nocturnal animals. One of the most important differences is the inclusion of flora in the experts’ responses, with 8.16% identifying plant life as being impacted. The public perception group does not mention flora at all.

This reflects a significant knowledge gap: while public perception may think of animals when considering environmental impacts, experts are aware that light pollution also affects plants—altering their photoperiodism, disrupting flowering cycles, and even affecting the species composition of plant communities. Another divergence is the mention of climate change by 11.11% of non-experts. This issue is absent from the expert group’s responses, indicating that some people from the public perception group may mistakenly associate all environmental problems with the umbrella of climate change, possibly due to general environmental discourse that frequently centers on it. This conflation highlights a lack of clarity in the public’s understanding of how different environmental stressors operate independently, even if they occasionally intersect. Finally, the mention of skyglow by a small portion (1.86%) of public perception and not at all by experts may indicate a more observational concern rather than ecological laypeople may be more sensitive to the visual and esthetic degradation of the night sky, while experts prioritize measurable biological impacts.

Overall, the comparison reveals a clear separation: public perception tends to view light pollution’s ecological effects in broad, sometimes vague terms, and occasionally confuse it with unrelated environmental issues, while experts demonstrate a more technical, differentiated, and biologically grounded understanding. Bridging this gap through education and communication is essential to empower the public to make informed decisions and support policies aimed at mitigating light pollution and preserving biodiversity.

3.3.2. Human Health and Well-Being

The views on how light pollution affects human health and well-being reveal significant differences in both the prioritization of issues and the depth of understanding behind them (Figure 7). The most striking contrast lies in how each group views the impact on circadian rhythms. While only 16.98% of the public perception group respondents identified circadian rhythm disruption as a major consequence of light pollution, nearly 40% (39.66%) of the expert group highlighted this as the primary concern. This discrepancy reflects a clear divide in understanding; experts, informed by scientific evidence, recognize the disruption of the circadian system—our internal biological clock—as a fundamental mechanism through which artificial light at night influences sleep, hormonal regulation, and overall health. In contrast, the general public seems not to be aware of this underlying biological process, leading them to overlook it in favor of more observable or commonly discussed effects.

Psychological disorders were emphasized by the public perception group far more than by experts—32.08% versus 15.52%. This suggests that the public may be more likely to attribute mental health issues to environmental stressors like light pollution, possibly reflecting a growing societal awareness of mental health but lacking specificity regarding causation. Experts, however, approach such associations with greater caution, recognizing the multifactorial nature of psychological disorders and the need for stronger causal links. Sleep disorders were identified at nearly equal levels by both groups—20.75% for non-experts and 20.69% for experts—indicating some shared understanding of the relationship between light exposure and sleep quality. This may be due to increased public awareness campaigns or media coverage highlighting how screens and artificial light can affect sleep, making this one of the more universally acknowledged impacts. Pathological diseases such as eye disorders and cancer were more frequently cited by public perception (18.87%) compared to experts (6.90%). This could reflect a tendency among the general public to associate environmental issues with serious health outcomes, even when scientific evidence is still evolving or not widely known. Experts are more reserved in this regard, likely due to the ongoing nature of research and the current limitations in directly linking light pollution to major diseases like cancer. Light sensitivity was another point of divergence. Experts (10.34%) gave this more attention than public perception (3.77%), suggesting that those with deeper knowledge recognize the nuanced ways in which individuals may experience discomfort or health issues due to increased exposure to artificial light, even if such effects are less dramatic than sleep or psychological disruptions. Notably, 3.45% of experts believed that light pollution does not affect human health, an absent perspective among the general public. This could indicate either a critical stance toward the strength of current evidence or a professional view that other environmental factors may be more pressing. Conversely, it might reflect a higher threshold among experts for establishing health impacts, whereas the general public may be more inclined to attribute harm even when the evidence is indirect.

Finally, while both groups included a small percentage of “Other” responses, the variation in how they prioritized specific health outcomes reveals a deeper pattern: experts approach the topic from a scientific and physiological standpoint, rooted in research on biological rhythms and environmental health, while the general public responds more intuitively or emotionally, based on visible or widely discussed outcomes like mental health and serious diseases. This comparison underscores the importance of bridging the knowledge gap with effective science communication to ensure public understanding aligns more closely with evidence-based concerns.

3.3.3. Environment and Climate Change

During the analysis in the sector of environment and climate change, some key trends and insights on how each group perceives the environmental impact of light pollution stand out (Figure 8). The public perception group seems to have a broader and perhaps more generalized view of light pollution’s impact on this topic. Their highest concern is global warming (23.53%), which aligns with how the issue is often presented in mainstream discourse—light pollution is viewed primarily as a driver of broader climate change. This suggests that public perception might connect light pollution to larger, more well-known environmental challenges, such as global warming, without considering the nuances of how light pollution specifically contributes. Similarly, this group also associates light pollution with climate change (3.92%), but this seems to be a less significant concern compared to other issues like global warming or energy waste. In essence, the public’s focus is likely shaped by high-profile environmental narratives that link pollution to large-scale climate problems, without delving into finer details.

On the other hand, the group of experts has a more nuanced and specialized understanding of light pollution’s environmental impacts. They identify energy waste as the most significant concern (27.08%), which is a direct consequence of poor lighting practices such as excessive brightness and use of inefficient lighting. This recognition of energy waste as the leading issue suggests that the expert group has a deeper understanding of how light pollution contributes to resource inefficiency and unnecessary energy consumption, which is a major concern within the field of lighting design and sustainability. Ecosystem disruption, including biodiversity issues and habitat disruption, also stands out as a major concern for experts (20.83%). This focus reveals a greater awareness of the direct ecological effects of light pollution—such as its impacts on wildlife, migratory patterns, and the functioning of natural ecosystems. While the public perception group also noted ecosystem issues (13.73%), they seemed less attuned to the complexity of these ecological disruptions. The expert group’s higher prioritization of this factor indicates a specialized understanding of how artificial light can interfere with nocturnal behaviors and disrupt ecosystems in ways that are less visible to the general public. Interestingly, the expert group places significant emphasis on greenhouse gas emissions (18.75%), which is a more specific and technical consequence of energy waste and inefficient lighting. This suggests that those with experience are better equipped to link the data between light pollution, energy consumption and its wider environmental consequences, including the contribution to climate change through higher greenhouse gas emissions. This is a more sophisticated perspective that extends beyond the general view of climate change and focuses on the detailed mechanisms through which light pollution exacerbates environmental issues. In comparison, the public perception group appears less concerned with greenhouse gas emissions (with only 3.92% noting it as a key issue) and more focused on the broad consequences like global warming and carbon footprint (11.76%). This highlights a gap in understanding: while both groups acknowledge that light pollution has an environmental impact, those without expertise might not fully grasp the technical connections between energy consumption, greenhouse emissions, and ecosystem disruption. Instead, they tend to frame light pollution primarily within the context of global warming or climate change, without necessarily linking it to specific environmental mechanisms, like carbon emissions from inefficient lighting. Furthermore, the expert group shows a more critical awareness of the specific ways that light pollution affects the environment, while the public perception group seems to lack this level of specificity. For example, the expert group is highly aware of the carbon footprint (16.67%) associated with light pollution, whereas this is a less emphasized concern for public perception (11.76%). This highlights that while the general public may view light pollution as an issue broadly tied to climate change, experts understand the nuances, including how it directly contributes to emissions and environmental degradation.

Overall, the expert group’s responses demonstrate a more sophisticated understanding of light pollution’s environmental consequences. Experts can connect energy waste to specific emissions and the disruption of ecosystems, while public perception tends to see light pollution as part of a larger, less specific environmental problem, mostly related to climate change and global warming. This comparison suggests that public education and awareness campaigns around light pollution could benefit from a more detailed focus on the technical impacts, particularly on energy waste and ecosystem disruption, to bridge the knowledge gap between these two groups.

3.3.4. Energy Crisis

Comparing results from the two groups reveals a significant disparity in how they perceive the impact of light pollution related to energy crisis (Figure 9). This gap in understanding can be attributed to differing levels of familiarity with the technical and environmental aspects of lighting.

The public perception group, with little to no specific knowledge about lighting issues, tends to respond with a broader, less informed view. The largest concern for this group is energy waste, which accounts for 39.03% of responses. However, this is not as prominent a concern as it is for the experts, who recognize its much larger role (60.78%). The public perception also highlights “loss of energy resources” at 21.95%, which is a legitimate concern, though experts view this issue as more of a secondary impact (25.49%). Furthermore, sustainability issues and energy costs are both cited by 14.63% of non-experts. This suggests that for those without detailed knowledge, the implications of light pollution may be seen through a more general perspective of inefficiency or environmental degradation rather than a specific technical problem. These respondents also exhibit a relatively higher level of uncertainty, with 7.32% of them responding with “Don’t know,” pointing to a lack of understanding or familiarity with the topic. A percentage of 2.44% who felt they were “not affected” could reflect either ignorance or a belief that the issue does not impact them directly, which might be due to a lack of awareness of the broader environmental or economic impacts. In contrast, the expert group shows a much more targeted understanding of the energy-related impacts of light pollution. The primary concern remains energy waste, but this issue stands out more sharply, with 60.78% of respondents citing it as the most significant problem. This higher percentage likely reflects their technical understanding of the inefficiencies created by excess artificial lighting. Energy waste is a direct consequence of light pollution, especially in the form of poorly designed or unnecessary lighting that consumes power without serving a useful purpose. Loss of energy resources, while still important, is perceived as slightly less critical (25.49%) by this group, likely because they understand that it is a broader consequence of energy inefficiency rather than the core issue. The expert group also mentions sustainability issues at a lower rate (11.76%), suggesting that, while they recognize the environmental implications of light pollution, they place more focus on the immediate technical and resource management challenges. The “Other” category is much more limited in this group (1.96%), implying that the experts are less likely to see nuances beyond the main issues already identified. What stands out most in the comparison is the difference in perceived urgency and the level of specificity in addressing the energy crisis caused by light pollution. Non-experts seem to consider the problem more holistically—energy waste, sustainability, and energy costs are all seen as interconnected in a general way, but without a clear understanding of the technical mechanisms at play. This lack of detail is reflected in the higher percentage of “Don’t know” responses, indicating that many in this group do not fully grasp the underlying dynamics of light pollution’s role in the energy crisis. For the experts, however, the concern is more defined and grounded in practical implications, particularly in the realm of energy efficiency and the technical aspects of lighting systems. Experts focus on energy waste with a clear understanding that inefficient lighting contributes directly to unnecessary energy consumption, which in turn exacerbates energy crisis.

In conclusion, the two groups differ not only in the degree of concern they express but also in how they conceptualize the problem. Public perception tends to offer a broader, more generalized view, focusing on the overall consequences like sustainability and energy costs, without necessarily understanding the root causes. In contrast, the expert group is more focused, recognizing energy waste as the primary issue and acknowledging it in more specific terms. This disparity highlights the importance of education and awareness in addressing environmental and energy-related challenges like light pollution.

3.3.5. Astronomy

The comparison between the two groups reveals notable differences not only in the distribution of responses but also in the depth of understanding and framing how light pollution affects astronomy (Figure 10). The most striking difference lies in how heavily public perception emphasizes astronomical observation, with 53.45% of them identifying it as the main area impacted. In contrast, only 35.42% of experts point to this as the primary issue. This suggests that the public perception is more likely to associate light pollution with the broad concept of observing celestial bodies, likely without distinguishing between scientific observation, casual stargazing, and atmospheric interference. For them, the immediate and most visible consequence of light pollution is the reduced ability to see stars and planets clearly—a view shaped by general experience rather than technical knowledge.

Experts, however, distribute their concerns more evenly across astronomical observation, stargazing, and skyglow, with 35.42%, 29.17%, and 22.92%, respectively. This distribution implies a more detailed understanding of the mechanisms and consequences of light pollution. The relatively high mention of stargazing by experts (nearly double compared to non-familiars) reflects an appreciation for how light pollution affects both professional astronomy and public engagement with the night sky. Skyglow also appears more frequently in experts’ responses (22.92% vs. 20.69%), hinting at a stronger awareness of the specific atmospheric scattering processes that obscure celestial visibility. Experts mention that the lack of policies (4.17%) and difficulty in photography (2.08%) are also significant. These opinions do not appear at all in public perception responses. This indicates that professionals are more attuned to systemic and technical challenges that go beyond what is immediately visible in the sky. Their reference to policy reflects awareness of how regulation (or the lack thereof) contributes to ongoing light pollution, and their concern with photography shows familiarity with the practical implications of light pollution on scientific documentation and imaging techniques. Meanwhile, public perception attributes a small percentage to “lack of education” (1.72%), possibly implying a perceived need for greater public awareness about light pollution. Interestingly, this is not mirrored in the experts’ responses, who believe that the issue lies more in policy and infrastructure than in general awareness. Both groups had a small percentage claiming that astronomy is not affected by light pollution (6.90% of public perception vs. 4.17% of experts), suggesting that the recognition of light pollution as a problem is fairly widespread in both groups, though slightly more among experts. This percentage of experts is unexpected, yet the authors consider it important to report. A consideration, perhaps more relevant to the experts, is that astronomy is controlled and studied by multiple methods, e.g., using Hubble, Webb, computer models, probes, etc., and not just through observation from the ground. Maybe that is the reason for their response. Also, it may prompt future discussions about what constitutes essential knowledge for an expert or unless it is seen as a percentage of error in the answers.

In summary, public perception tends to view light pollution through a more general and experiential lens, focusing heavily on its impact on direct visual observation. Experts, on the other hand, exhibit a more nuanced and multi-dimensional understanding that incorporates technical, recreational, and policy-related aspects. This contrast underlines the importance of interdisciplinary dialog and public education, as bridging the gap between these perspectives that could lead to more effective advocacy and solutions for preserving the night sky.

3.4. Analysis of Sectors Related to Socio-Economic CONCERNS

3.4.1. Politics

The comparison between the two groups reveals significant differences not only in what they believe links light pollution to politics, but also in how they conceptualize political responsibility and systemic issues (Figure 11). One of the most striking contrasts lies in the prioritization of issues.

Public perception overwhelmingly attributes the political dimension of light pollution to financial and political interests (35.42%), suggesting a belief that vested interests dominate decision-making. This reflects a broader distrust in political processes, where economic gain or political alliances may override environmental or public health concerns. In contrast, experts do not prioritize this issue at all; they focus instead on structural and policy-related shortcomings, with nearly 40% citing the lack of policies. This suggests that experts view the political impact of light pollution as more systemic and institutional—highlighting the absence or inadequacy of legal frameworks rather than assuming active interference by powerful stakeholders. Another point of divergence is in the perception that politics are not affected by light pollution. While this belief is present in both groups, it is more prevalent among public perception (33.33%) than among experts (23.26%). This could indicate that public perception may see light pollution as a niche or technical issue, too disconnected from broader political agendas to merit attention. Experts, on the other hand, are less likely to see it as politically irrelevant, possibly because they are more aware of how lighting intersects with urban planning, public safety, energy policy, and environmental regulation. The call for legislative review—identified by 18.60% of experts but not mentioned at all by public perception —adds another layer to the contrast. It reflects an understanding among experts that existing laws may be outdated, poorly enforced, or insufficient to tackle the modern realities of light pollution. This response implies a belief in the potential for reform through established political and legal channels, which contrasts with the more cynical or detached view often held by public perception. Lack of interest or ignorance is mentioned by both groups, though it is slightly more prevalent among public perception (12.5%) than experts (9.3%). This may represent a shared recognition that light pollution is a low-priority issue on the political agenda. However, experts likely view this disinterest as part of a broader failure to recognize or act upon scientific and environmental evidence, while public perception may see it as political apathy or distraction by more pressing issues. Finally, both groups mention lack of knowledge, though experts (4.65%) are more likely to highlight this than public perception (2.08%). This is particularly telling: experts are likely to observe gaps in both public and political understanding of light pollution, which could hinder meaningful action. Public perception may not fully recognize these knowledge gaps, reinforcing the idea that public awareness campaigns and education could play a key role in shifting perceptions.

In summary, the comparison highlights a diversification between the structural, policy-focused view of experts and the more generalized, often skeptical view of public perception. While public perception tends to attribute political inaction to hidden interests or irrelevance, experts point to tangible deficiencies in policy, legislation, and institutional awareness. This suggests that addressing light pollution politically will require both better public understanding and targeted policy reform—each group holds a different piece of the puzzle.

3.4.2. Economy

In the case of the economy, energy-related impacts dominate the responses of both groups, but the emphasis differs (Figure 12). Public perception overwhelmingly points to energy costs as the top economic issue (53.23%), likely because these are immediate and tangible—household and municipal electricity bills are directly felt. In contrast, experts prioritize energy waste (37.5%) over energy costs (27.08%). This distinction reflects the perspective of an individual or consumer to a systemic or infrastructural one.

Experts may be considering the inefficiencies in lighting systems, over-illumination, and misdirected light that drive unnecessary energy use on a broader scale, which might not immediately translate into visible costs for common people but have large-scale environmental and economic consequences. Moreover, the range and distribution of concerns point to a broader and more nuanced understanding among experts. While the general public shows a steep drop in percentage after the top one or two issues, experts’ responses are more evenly spread across categories like loss of productivity (8.33%), repulsion of astronomy tourists (4.17%), and even “Other” (8.33%), which suggest awareness of complex or indirect economic effects. This indicates that professionals consider a wider spectrum of economic links, possibly including effects on wildlife, policy costs, or innovation barriers, even if these were not listed as options in the survey. Another key difference lies in skepticism or critical distance. A higher proportion of experts (12.5%) believe that light pollution does not affect the economy, compared to only 6.45% of public perception. This may reflect a more measured assessment, suggesting that while light pollution has ecological or social impacts, its direct influence on the economy may not be as straightforward or as severe as assumed by the general public. Experts may also be better equipped to distinguish between causation and correlation in these matters.

Furthermore, public perception cited health expenses (4.84%) and climate strategy funding (1.61%) more often than experts (2.08% and not mentioned, respectively), which might indicate broader environmental concerns or a conflation of light pollution with other environmental issues. This could lead to a lower level of specific knowledge, leading to more generalized environmental anxiety being associated with light pollution. Finally, while tourism-related concerns were mentioned by both groups, the framing is more refined among experts—repulsion of astronomy tourists rather than simply repulsion of tourists—highlighting a deeper understanding of specific economic sectors uniquely sensitive to light pollution.

In sum, the public perception tends to perceive economic impacts through a personal, immediate view, focusing on visible outcomes like costs. Experts, on the other hand, show a more systemic and diversified perspective, highlighting inefficiencies, sector-specific impacts, and in some cases, questioning the overall economic significance. This contrast underscores how technical knowledge shapes not only what people believe is important but also how they interpret and prioritize complex environmental problems.

3.4.3. Safety and Security

On issues relating to safety and security, several differentiated aspects emerge. For the public perception, over-illumination stands out as the primary concern, with 35.13% of respondents pointing to this issue (Figure 13). This indicates that for the general public, the most noticeable or understandable consequence of light pollution is simply too much light. This concern likely stems from the discomfort caused by excessive brightness in residential or public spaces. Additionally, a large percentage of respondents, 21.62%, do not feel informed enough to answer the question, further highlighting the lack of awareness around the technical aspects of lighting and its broader implications.

A percentage of 18.92%, indicating that they were not affected by light pollution, suggests that for many people the immediate effects of light pollution might not be a pressing issue, especially in areas where it has not reached disruptive levels. Interestingly, road safety issues related to glare and visibility were only mentioned by 8.11% of public perception, suggesting that this concern is not as prominent or well-understood by the general public. This low figure could reflect a lack of recognition of how light pollution affects driving conditions or pedestrian safety, particularly in terms of reduced visibility caused by improperly designed lighting. On the other hand, the expert group, with its specialized knowledge, offers a more complex and nuanced understanding of how light pollution affects safety and security. While over-illumination remains a key issue (34.88%), experts acknowledge a broader spectrum of problems. For instance, 27.91% of experts mentioned that moderate light levels could improve safety, an important consideration that suggests they view lighting not just as a source of illumination but as a tool that, when applied thoughtfully, can enhance security. This perspective is a clear indication that experts understand that too much light can be just as harmful as too little, and finding the right balance is crucial for both safety and the reduction in light pollution. Experts also brought up light trespass (16.28%), an issue less recognized by public perception group. Light trespass occurs when unwanted light spills into private or unintended areas, potentially disrupting the sleep and well-being of residents. This concern highlights the experts’ awareness of the more subtle forms of light pollution that may not be immediately apparent to the public’s perception but can have significant long-term effects on health and quality of life. This also speaks to their deeper understanding of how light should be directed and controlled to prevent these unwanted side effects. Road safety, including glare and visibility, was mentioned by 11.63% of experts. Although this is still a notable issue, it is less emphasized than other concerns like over-illumination and light trespass, perhaps because experts recognize that this problem, while important, is somewhat addressed by proper lighting design and regulation. The lower percentage compared to public perception (who listed it at 13.04%) could suggest that experts take a more holistic approach to lighting, considering the broader environmental impacts and potential solutions that address safety in a more integrated way. Finally, only 9.30% of experts cited “Other” issues, reflecting a more focused and specific set of concerns compared to the public perception, who had a wider range of responses in the “Other” category (16.22%). This could indicate that experts have a more precise understanding of the issues at hand, focusing on technical aspects like light distribution and environmental impacts, while public perception may be more influenced by immediate, visible effects like glare and excessive lighting.

In summary, while both groups recognize the disruptive effects of light pollution, their concerns and understanding differ significantly. Public perception tends to focus on more immediate, visible problems such as over-illumination and the discomfort it causes, with less awareness of the more subtle and complex effects of light pollution. In contrast, experts display a deeper understanding of the issue, with concerns spanning from over-illumination to light trespass and the importance of moderate light levels used for safety. The expert group’s responses reflect a more sophisticated, technical perspective on how to balance lighting for optimal safety and environmental impact, while the non-expert group’s responses are shaped by more general, everyday experiences of light pollution.

3.4.4. Tourism

When comparing the responses of the two groups, it becomes clear that their perspectives on the impact of light pollution on tourism are shaped by their level of knowledge and understanding of the issues at hand (Figure 14). Both groups identified the loss of darkness as the primary concern. However, the group without lighting expertise is significantly more concerned about it, with 25.58% of respondents highlighting it.

This suggests that the general public’s understanding of light pollution may be centered more around the immediate, visible effects—like how light pollution obscures the night sky or diminishes the experience of a natural, dark environment. In contrast, the expert group, while still recognizing the loss of darkness as important (22.22%), shows a relatively lower level of concern. This might reflect a deeper understanding among experts of the various, more complex dimensions of light pollution that extend beyond just the absence of darkness.

A key distinction between the two groups is in their focus on natural beauty and over-lit monuments. The group with expertise in lighting places a greater emphasis on the loss of natural beauty, with 20.00% of experts identifying this issue. This suggests that experts are more attuned to the nuanced environmental and esthetic impacts that light pollution has on landscapes, ecosystems, and the natural scenery that is integral to many tourist experiences. On the other hand, the public perception group only cited this issue at a much lower rate (13.95%), potentially indicating a more superficial or general appreciation of beauty, without a full understanding of how artificial lighting impacts the environment. The issue of over-lit monuments and attractions is another point of divergence. This concern is far more pronounced in the expert group (13.33%), reflecting their awareness of how excessive lighting can not only distort the appearance of historical or cultural landmarks but also negatively affect tourism by diminishing the value of these sites. For the public perception group, only 4.65% cited this issue, which suggests they might not fully grasp the significance of how lighting decisions on monuments can alter visitors’ experience. A clear difference arises in the expert group’s attention to eco-tourism (11.11%), a category that was not identified at all by the non-expert respondents. This indicates that those with expertise in lighting are more aware of the environmental aspects of tourism and the consequences of light pollution on wildlife, natural habitats, and the overall ecological balance in tourist destinations. For public perception, eco-tourism might not be as immediate a concern because they tend to focus more on visual and cultural factors rather than broader environmental impacts. The impact of light pollution on astrotourism is a shared concern in both groups, but it is more pronounced among the public perception group (6.98%) compared to the expert group (6.67%). This could suggest that people without expertise are more likely to associate light pollution with the loss of stargazing opportunities, an issue that is often more publicized. Experts may be more cognizant of the broader, less publicized effects that light pollution has on other forms of tourism. The public perception group is notably more concerned about the attempt to impress by the amount of light (18.60%), suggesting that they view light as a tool used by businesses and tourist destinations to attract attention, sometimes excessively. This highlights how the general public may view lighting in a more superficial, esthetic way, focused on the impression it gives rather than its long-term consequences. The expert group, however, recognizes this issue at a lower rate (15.56%), which might reflect their understanding of how excessive lighting is not only impractical but can also have detrimental effects on the environment and tourism. Another distinction between the two groups is the mention of policy and advertising. Only the public perception group mentioned a lack of policies (2.33%), which could imply a recognition that there is a need for more regulation in how lighting is managed, though they may not fully appreciate the depth of policy involvement required to address light pollution. The expert group, in contrast, flagged advertisement (2.22%) as a concern, suggesting that experts may see the excessive use of lighting for promotional purposes as a form of light pollution in itself, potentially distracting from the natural or cultural experience. The fact that this concern emerged only in the expert group points to their greater understanding of how lighting is used in commercial contexts. Finally, both groups selected the “Other” category to describe additional concerns, but the non-expert group listed this category more frequently (16.28%), indicating that there are likely many issues the general public perceives but may not be fully articulated in the survey options. This could reflect a broader sense of discontent with the effects of light pollution, but without a detailed understanding of the specific ramifications. In contrast, the expert group’s “Other” responses (8.89%) might reflect more specific, technical concerns not captured by the predefined categories.

Overall, the comparison reveals that the group with expertise in lighting tends to recognize more complex, long-term, and environmental impacts of light pollution, such as its effects on eco-tourism, the natural beauty of destinations, and over-lit monuments. Experts are also more concerned about the implications of light for environmental sustainability and the regulation of lighting practices. On the other hand, the public perception group is more focused on the visible, esthetic, and immediate aspects of light pollution, like the loss of darkness and the attempt to impress through excessive lighting. The general public is also more likely to connect light pollution with astronomy tourism (stargazing, dark sky parks, etc.), while experts are more likely to consider the broader environmental and policy implications. This contrast highlights the different levels of understanding between the two groups, with experts offering a more nuanced and environmentally aware perspective on the challenges posed by light pollution to tourism.

4. Discussion and Conclusions

The paper explores differences between expert and public perceptions of light pollution impacts. It quantified expert views across sectors, comparing overall concern levels and whether these differences remained across sector types. Using Principal Components Analysis, sectors are grouped into two factors: one focused on environmental aspects and the other on social and economic dimensions. The main finding is that expertise significantly increases awareness, as the expert group consistently showed higher levels of concern about light pollution. This result appears robust, having been tested under various model specifications that included a wide range of control variables. In the second stage, the analysis focused on sector-specific concern levels. It revealed that expert concern is significantly higher only for impacts related to the environment and human well-being, while no significant difference was found regarding the socio-economic impacts of light pollution. The comparison between public perception and lighting experts reveals clear and consistent differences in how light pollution is perceived and understood across a range of sectors. In fields like astronomy and ecology, public perception tends to interpret light pollution through a general or personal perspective, focusing on visible effects and sometimes conflating issues. Experts, however, provide more nuanced and detailed assessments that incorporate scientific knowledge, policy implications, and sector-specific impacts. These differences highlight the importance of fostering interdisciplinary communication and enhancing public education to create a shared understanding of the issue. In domains such as energy use, environmental sustainability, health, and the economy, the gap in understanding becomes even more pronounced. Public perception typically expresses broader or more emotionally driven concerns—like rising energy costs or visible health symptoms—while experts ground their perspectives in research and data, pointing out specific mechanisms such as energy inefficiency, disrupted circadian rhythms, and long-term economic consequences. These contrasting viewpoints emphasize the critical need for effective science communication strategies that translate complex technical information into accessible and actionable knowledge for the general public. Areas like tourism, safety, and politics further illustrate how diverging levels of understanding shape the way each group interprets and responds to light pollution. Public perception focus on immediate experiences and visible outcomes, while experts highlight systemic and long-term consequences, as well as the importance of regulation and policy. These insights make it clear that tackling light pollution effectively requires a dual approach: improving public awareness, education and engagement while also advancing expert-driven policy solutions. Bridging the knowledge gap between experts and the general public is not only vital for more informed decision-making but also essential for building collective momentum toward sustainable and balanced lighting practices that benefit society as a whole. To close this gap, targeted communication campaigns, inclusive stakeholder dialogs, and participatory planning processes should be implemented. These strategies can ensure that scientific knowledge is translated into accessible information and that public concerns are reflected in policy design. In recent years, awareness and education around light pollution have been significantly advanced by the Dark Sky authority. This effort also promotes the creation of designated dark sky places—such as sanctuaries, parks, and reserves—where stargazing events and educational programs are regularly organized, a requirement for maintaining accreditation [19]. A notable recent example is the designation of Aenos National Park in Greece as the first International Dark Sky Park in southeastern Europe [77]. Despite the valuable role these parks play in raising public awareness, they remain relatively few worldwide. To address this, comprehensive policies should be gradually developed to integrate light pollution education into school curricula and broader environmental strategies.