Search Results (127)

Potamogeton crispus (P. crispus), with strong nitrogen uptake capacity, plays an important ecological role during winter and early spring when most aquatic plants are inactive. Its presence can also influence microbial denitrification in sediments by regulating oxygen levels and organic carbon availability. In this study, an indoor hydroponic simulation system was used to systematically evaluate the effects of P. crispus under different nitrogen-loading conditions on nitrogen removal from water, changes in sediment carbon and nitrogen fractions, microbial community structure, and greenhouse gas fluxes. The results showed that P. crispus effectively removed TN, NH₄⁺-N, NO₃⁻-N, and NO₂⁻-N, maintaining strong denitrification capacity even under high-nitrogen loading. Under all nitrogen conditions, TN removal exceeded 80%, while NH₄⁺-N and NO₃⁻-N removal efficiencies surpassed 90%, with effective suppression of NO₂⁻-N accumulation. Rhizosphere-mediated regulation by P. crispus enhanced the transformation and stabilization of DOC and NO₃⁻-N in sediments, while also mitigating nitrogen-induced disturbances to carbon–nitrogen balance. The plant also exhibited strong CO₂ uptake capacity, low CH₄ emissions with a slight increase under higher nitrogen loading, and N₂O fluxes that were significantly affected by nitrogen levels—showing negative values under low nitrogen and sharp increases under high-nitrogen conditions. Correlation analyses indicated that CO₂ and N₂O emissions were mainly regulated by microbial taxa involved in carbon and nitrogen transformation, while CH₄ emissions were primarily driven by methanogenic archaea and showed weaker correlations with environmental factors. These findings highlight the importance of water restoration during low-temperature seasons and provide a theoretical basis for integrated wetland management strategies aimed at coordinated pollution reduction and carbon mitigation. Full article

Particulate matter (PM) has been associated with various health issues. However, the most hazardous constituents of fine particles remain unclear, particularly in Asia where the chemical compositions are highly diverse and understudied. This study investigated the concentration and health risks of particulate-bound polycyclic aromatic hydrocarbons (PAHs) and heavy metals in the indoor air of religious spaces in Bangkok, Thailand. Air samples were collected from four religious sites during periods of high activity using a six-stage NanoSampler to capture particle sizes ranging from <0.1 to >10 µm. Chemical analyses were conducted using gas chromatography-mass spectrometry (GC-MS/MS) for PAHs and inductively coupled plasma-mass spectrometry (ICP-MS) for heavy metals. The results revealed significantly elevated concentrations of PM2.5, PAHs (notably benzo[a]anthracene (BaA), chrysene (CHR), and fluoranthene (FLU)), and heavy metals (particularly Mn, Ni, and Cu). Health risk assessments indicated that both the incremental lifetime cancer risk (ILCR) and hazard quotient (HQ) values for several pollutants exceeded the U.S. EPA safety thresholds, suggesting serious cancer and non-cancer health risks for workers exposed to these environments over prolonged periods. This study highlights incense burning as a dominant source of toxic indoor air pollutants and underscores the urgent need for mitigation strategies to reduce occupational exposure in religious buildings. Full article

In the past decades, both low-cost gas sensors for air quality monitoring and smartphone devices have experienced a remarkable spread in the worldwide market. Smartphone devices have become a unique tool in everyday life, whilst the use of low-cost gas sensors in air quality monitors has allowed for a better understanding of the personal exposure to air pollutants. The traditional technologies for measuring air pollutant concentrations, even though they provide accurate data, cannot assure the necessary spatio-temporal resolution for assessing personal exposure to the various air pollutants. In this respect, one of the most promising solutions appears to be the use of smartphones together with the low-cost miniaturized gas sensors, because it allows for the monitoring of the air quality characterizing the different environments frequented in everyday life by leveraging the capability to perform mobile measurements. In this research, a handheld air quality monitor based on low-cost gas sensors capable of connecting to smartphone devices via Bluetooth link has been designed and implemented to explore the different ways of its use for assessing the personal exposure to air pollutants. For this purpose, two experiments were carried out: the first one was indoor monitoring of CO and NO₂ concentrations performed in an apartment occupied by four individuals and the second one was mobile monitoring of CO and NO₂ performed in a car cabin. During the indoor measurements, the maximum value for the CO concentrations was equal to 12.3 ppm, whilst the maximum value for NO₂ concentrations was equal to 64 ppb. As concerns the mobile measurements, the maximum concentration of CO was equal to 8.3 ppm, whilst the maximum concentration of NO₂ was equal to 38 ppb. This preliminary study has shown that this system can be potentially used in all those situations where the use of traditional chemical analyzers for measuring gas concentrations in everyday life environments is hardly feasible, but also has highlighted some limits concerning the performance of such systems. Full article

Many US states have adopted regulations to divert food waste from landfills to composts. While this may lower greenhouse emissions from landfills, volatile organic compound (VOC) emissions from compost may contain hazardous air pollutants or produce odors, posing potential public health concerns. Effective methods to analyze speciated VOCs in compost are needed to better understand VOC source generation. Here, a two-component compost sampling method was developed and employed consisting of a chilled impinger and pump apparatus to trap water-soluble VOCs, and dual sorbent tubes to capture hydrophobic VOCs in yard and food/yard waste compost. VOCs were measured via headspace gas chromatography with flame ionization detection (HS-GC-FID) and thermal desorption–gas chromatography–mass spectrometry (TD-GC-MS). Overall, there was higher VOC generation within higher-temperature compost piles, with concentrations ranging up to 27,000 ppm for ethanol and 3500 ppm for methanol. Alpha-pinene and D-limonene were seen in these piles with concentrations over 1600 ppb. Methanol and ethanol were more than one thousand times as concentrated in mixed food/yard waste than yard waste alone, while terpenes were seen in slightly higher concentrations for yard waste than the mixed food/yard waste. Methanol was observed to be higher than permissible indoor levels and may pose potential health risks. Full article

A project to assess air pollution at the National Archeological Museum in Naples was carried out. The main goal of the project was to develop and test a reliable yet simple monitoring system to be adopted at the same time in several exposition rooms. Nitrogen dioxide, hydrogen chloride, nitrous acid, and sulphur dioxide were the chemical species addressed by the technique. Monitoring was simultaneously performed in five rooms, and pollutant concentrations were determined using two passive samplers. The sampling time was approximately one month per period. In addition to passive samplers, environmental data loggers were used to obtain temperature and relative humidity data. Results show high concentrations of nitrogen dioxide inside rooms, which were consistent with those found in outdoor environments and are close to the values calculated considering the air exchange rates, estimated through time gradients of ambient temperature. The minimum values were recorded in a basement room that had a low ventilation rate. The conversion of nitrogen dioxide to real surfaces produces nitric acid and nitrous acid. Large amounts of nitrous acid, up to 15 µg/m³, were found in exposition rooms, with maximum values in the basement room, where the air exchange rate is limited, and the surface-to-volume ratio is the highest among the monitored rooms. Data analysis demonstrated that the system could discriminate between nitrous acid and nitrogen dioxide. The results show that, for the first time, passive samplers can overcome the problem of mutual interference between nitrogen-containing species. Nitrates and nitrites found in the alkaline passive sampler were generally found not to be interfered by nitrogen dioxide. Nitric acid was also found in the gas phase, likely generated by dissociation of ammonium nitrate in particulate matter. Hydrogen chloride and sulphur dioxide were present at few µg/m³. Nitrous acid is the most relevant acidic species found indoors. The presence of pollutants was discussed in terms of the reliability of the analytical procedure and its significance for indoor air pollution. Full article

The utilization of 3D printing releases a multitude of harmful gas pollutants, posing potential health risks to operators. Materials extrusion (ME; also known as fused deposition modeling (FDM)), a widely adopted 3D printing technology, predominantly employs acrylonitrile–butadiene–styrene (ABS) and polylactic acid (PLA) as printing materials, with the respective market shares of these materials reaching approximately 75%. The extensive usage of ABS and PLA during the ME process leads to significant volatile organic compound (VOC) emissions, thereby deteriorating the quality of indoor air. Nevertheless, information regarding the emission characteristics of VOCs and their influencing factors, as well as the toxicological impacts of the printing processes, remains largely unknown. Herein, we thoroughly reviewed the emission characteristics of VOCs released during ME printing processes using ABS and PLA in various printing environments, such as chambers, laboratories, and workplaces, as well as their potential influencing factors under different environmental conditions. A total of 62 VOC substances were identified in chamber studies using ABS and PLA filaments; for example, styrene had an emission rate of 0.29–113.10 μg/min, and isopropyl alcohol had an emission rate of 3.55–56.53 μg/min. Emission rates vary depending on the composition of the filament’s raw materials, additives (such as dyes and stabilizers), printing conditions (temperature), the printer’s condition (whether it has closure), and other factors. Additionally, we reviewed the toxicological concerns associated with hazardous VOC species commonly detected during the ME printing process and estimated cancer and non-cancer risks for users after long-term inhalation exposure. Potential health hazards associated with inhalation exposure to benzene, formaldehyde, acetaldehyde, styrene, and other substances were identified, which were calculated based on concentrations measured in real indoor environments. This study provides valuable insights for future research on the development of ME printing technologies and offers suggestions to reduce VOC emissions to protect users. Full article

Sustainability has become an important focus in the construction industry due to growing environmental concerns, resource depletion, and the urgency to reduce greenhouse gas emissions. The construction sector contributes significantly to the world’s carbon emissions and energy consumption, making it a prime candidate for sustainable transformation. In response to these challenges, there has been a shift towards utilizing earth-based products, especially earth blocks, as sustainable alternatives. Compressed stabilized earth blocks (CSEBs) are garnering increased attention because of their ability to lower environmental impact. These blocks are made from locally sourced materials, reducing the transportation-related emissions and energy use. Their production processes typically require far less energy than traditional building blocks, which results in reduced carbon footprints. Earth blocks also contribute to sustainability through their thermal performance, which can enhance energy efficiency in buildings by naturally regulating indoor temperatures. As a result, less artificial heating and cooling is required, leading to further energy savings. Furthermore, CSEBs and other earth blocks can incorporate waste materials promoting a circular economy and resource efficiency. This paper explores the multifaceted role of earth blocks in sustainable construction by conducting a comprehensive systematic and bibliometric analysis. By evaluating research trends, the evolution of the field, and the broader impact of these materials, this study aims to provide a deeper understanding of the contributions of earth blocks to sustainability. Key areas of focus include identifying prominent research themes, emerging technologies, and future opportunities for incorporating earth blocks into mainstream construction practices. This approach aligns with the vision of advancing sustainable architecture and green buildings to minimize environmental pollution and resource consumption while supporting the transition to a circular economy in the built environment. Full article

This article considers issues related to air pollution in residential apartments equipped with gas stoves. The combustion products from gas stoves are released directly into the indoor air, where people can spend a significant part of their time. Even relatively low concentrations of harmful substances contained in combustion products can pose serious health risks and potentially threaten lives. The detrimental effects of nitrogen oxides (NO_x) on human health and the environment are briefly analyzed. A comparison and analysis of legal regulations and standards regarding the maximum permissible concentration of NO_x in the air across various countries are conducted. Theoretical calculations estimating the potential NO_x levels in gas-equipped kitchens are presented. Additionally, the results of experimental studies measuring the NO_x concentrations in the air of apartments with different gas stove designs, burner types, and ventilation methods are presented. The authors’ data are compared with existing data from other similar studies. Full article

The negative ion air purifier (NIAP) has been used for capturing particulate matter. Nevertheless, the knowledge on its effectiveness in removing other air pollutants such as ammonia gas remains limited. In this study, the effect of an NIAP for indoor ammonia gas removal was evaluated through a series of experimental studies. The applicability and different influencing, operating, and environmental factors on the ammonia gas removal performance were firstly investigated by conducting a series of experiments. Then, in order to understand the performance of the NIAP and the spatial distribution of ammonia gas and other by-products, indoor field measurements of ammonia gas, ozone, and negative ion concentrations in a real bathroom were performed for different cases with the NIAP turned on and off. The results indicated that negative ions were effective in reducing ammonia gas concentration. The operating and environmental factors including upstream wind speed, degree of operating voltage, and initial ammonia gas concentration have great influences on the ammonia gas removal efficiency of the NIAP. The highest removal efficiency can reach to 95.8%, when the upstream wind speed was 0.8 m/s and the degree of operating voltage was at gear 3 (3.0 kV). The purification efficiency of ammonia gas for the NIAP could reach up to 80%. Full article

In this study, a performance comparison experiment with a vortex exhaust installed at the end of a ventilation device to enhance the effect induced by reducing indoor pollutants was conducted. The experiment was carried out by constructing a mock-up room with a limited indoor environment, and performances were compared based on the following two tests. First, to confirm the effect of pollutant reduction, the wind speed was measured based on the distance from each exhaust system to verify the depth and speed at which wind can flow. Pollutants were induced to the vortex exhaust, general exhaust gasses were generated, and their performances were compared. Second, Arizona dust was used to confirm the performance with regard to the removal of pollutants which existed in particulate form (PM 10), and for CO₂ gas, a representative gaseous pollutant was used as a reference. Based on the results, it was confirmed that installing a vortex exhaust system can allow for the generation of wind speeds that allow propagation at greater depths (>110 mm) compared to cases in which general exhaust is used; accordingly, exhaust performance can be achieved at increased depths. In addition, the experiment confirmed that vortex exhaust can improve the efficiency of simultaneous removal of PM 10 and CO₂ compared with general exhaust. Further, it was shown that installing a vortex exhaust system can remove PM 10 and CO₂ farther from the exhaust port in a shorter period than a general exhaust port. In addition, it was inferred that vortex exhaust can be utilized to prevent indoor pollutants and diseases in combination with the latest technology. Full article

Nitrogen dioxide (NO₂) and particulate matter of 2.5 microns (PM_2.5) are air pollutants that impact health, especially among vulnerable populations with respiratory disease. This study identifies factors influencing indoor NO₂ and PM_2.5 in low-income households of older adults with asthma who use gas stoves in Lowell, Massachusetts. Environmental sampling was conducted in 73 homes, measuring NO₂, PM_2.5, fractional stove-use, temperature, and humidity for 5–7 days. Participants were recruited between December 2020 and July 2022. Questionnaires were used to collect data on factors influencing indoor NO₂ and PM_2.5 concentrations. Daily outdoor NO₂ and PM_2.5 concentrations were obtained from a United States Environmental Protection Agency (EPA) monitoring station. Paired t-tests were conducted between indoor and outdoor NO₂ and PM_2.5 concentrations, and linear regression was used to evaluate factors influencing indoor NO₂ and PM_2.5 concentrations. The average indoor concentration for NO₂ and PM_2.5 were 21.8 (GSD = 2.1) ppb and 16.2 (GSD = 2.7) µg/m³, respectively. Indoor NO₂ and PM_2.5 concentrations exceeded outdoor concentrations significantly. In multiple regression models, season and pilot light stove use significantly predicted indoor NO₂. Season and air freshener use for 6–7 days/week significantly predicted indoor PM_2.5. Season-influenced higher indoor concentrations are likely due to reduced ventilation in colder months in the Northeast U.S. Full article

This study investigated the prevalence of childhood asthma and respiratory symptoms with their associated air pollution sources among adolescents aged 13–14 years residing in a Malaria-endemic region. Methods: A cross-sectional survey was conducted with 2855 adolescents from fourteen (14) selected schools in communities exposed to high levels of air pollution from indoor residual spraying (IRS) that is used for malaria vector control in the Vhembe region. Data were collected using a self-administered standardized International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Statistical software STATA version 17 was used to analyze the data. Binary logistic regression was used to determine the relationship between air pollution sources and childhood asthma/symptoms. Results: The prevalences of asthma, ‘wheeze ever’ and ‘wheeze in the past’ were 18.91%, 37.69% and 24.69%, respectively. The results from the adjusted binary logistic regression model indicated that exposure to tobacco smoke (OR = 1.84; 95% CI: 1.08–3.16), smoking a water pipe (OR = 1.65; 95% CI: 1.16–2.36) and the use of paraffin as fuel for heating (OR = 1.70; 95% CI: 0.97–2.88) and cooking (OR = 0.48; 95% CI: 0.29–1.00) were significant risk factors for asthma. Trucks passing through the streets, having a cat at home and using open fires were significantly associated with ‘wheeze in the past’. Finally, using gas for cooking (OR = 0.72; 95% CI: 0.53–0.99), open fires for heating (OR = 0.53; 95% CI: 0.35–0.80) and smoking a water pipe (OR = 2.47; 95% CI: 1.78–3.44) were associated with ‘wheeze ever’. Conclusions: School children living in these communities had an increased risk of developing asthma and presenting with wheezing due to exposure to environmental air pollution sources. Full article

Light non-aqueous phase liquids (LNAPLs), which include various petroleum products, are a significant source of groundwater contamination globally. Once introduced into the subsurface, these contaminants tend to accumulate in the vadose zone, causing chronic soil and water pollution. The vadose zone often contains lens-shaped bodies with diverse properties that can significantly influence the migration and distribution of LNAPLs. Understanding the interaction between LNAPLs and these lens-shaped bodies is crucial for developing effective environmental management and remediation strategies. Prior research has primarily focused on LNAPL behavior in homogeneous media, with less emphasis on the impact of heterogeneous conditions introduced by lens-shaped bodies. To investigate the impact of lens-shaped structures on the migration of LNAPLs and to assess the specific effects of different types of lens-shaped structures on the distribution characteristics of LNAPL migration, this study simulates the LNAPL leakage process using an indoor two-dimensional sandbox. Three distinct test groups were conducted: one with no lens-shaped aquifer, one with a low-permeability lens, and one with a high-permeability lens. This study employs a combination of oil front curve mapping and high-density resistivity imaging techniques to systematically evaluate how the presence of lens-shaped structures affects the migration behavior, distribution patterns, and corresponding resistivity anomalies of LNAPLs. The results indicate that the migration rate and distribution characteristics of LNAPLs are influenced by the presence of a lens in the gas band of the envelope. The maximum vertical migration distances of the LNAPL are as follows: high-permeability lens (45 cm), no lens-shaped aquifer (40 cm), and low-permeability lens (35 cm). Horizontally, the maximum migration distances of the LNAPL to the upper part of the lens body decreases in the order of low-permeability lens, high-permeability lens, and no lens-shaped aquifer. The low-permeability lens impedes the vertical migration of the LNAPL, significantly affecting its migration path. It creates a flow around effect, hindering the downward migration of the LNAPL. In contrast, the high-permeability lens has a weaker retention effect and creates preferential flow paths, promoting the downward migration of the LNAPL. Under conditions with no lens-shaped aquifer and a high-permeability lens, the region of positive resistivity change rate is symmetrical around the axis where the injection point is located. Future research should explore the impact of various LNAPL types, lens geometries, and water table fluctuations on migration patterns. Incorporating numerical simulations could provide deeper insights into the mechanisms controlling LNAPL migration in heterogeneous subsurface environments. Full article

Indoor air quality (IAQ) has emerged as a global concern due to the increasing presence of indoor pollutants, which have been shown to negatively impact public health. These pollutants stem from various household activities and the materials used in buildings. Previous studies have explored several methods to improve IAQ, including gas adsorption, ozonation, non-thermal plasma, and photocatalytic oxidation (PCO). However, these methods often have drawbacks, such as generating secondary pollutants or incurring high costs. This study examines the effectiveness of photocatalytic paint, which is activated by visible light, in controlling fungal growth to enhance IAQ. Experimental results showed that when applied to grown fungi, the photocatalytic paint led to a significant reduction in the size of fungal fibers, as observed through scanning electron microscopy (SEM). Furthermore, exposure to the photocatalytic paint reduced the size of fungal hyphae by 37% after 85 h. The paint produced by adding 1 mL photocatalytic paint to 10 mL commercial paint demonstrated high efficiency in fungi removal, i.e., reducing the weight of fungi by approximately 45% within 3 h. These results highlight the potential of photocatalytic paint to significantly inhibit fungal growth, offering a promising solution for improving indoor environments. Full article

Natural gas (NG) is commonly used in kitchens, powering stoves, ovens, and other appliances. While it is known for its efficiency and convenience, NG contributes to the release of nitrogen dioxide (NO₂) and can have significant implications for human health. In this study, the importance of the use of NG in kitchens on human exposure to NO₂ was analyzed. An extensive literature review in the field was conducted, and the NO₂ levels were assessed in kitchens with NG cookers in Aveiro and electric cookers in Porto, both in Portugal. Higher levels of NO₂ were found in kitchens in Aveiro, where NO₂ levels outdoors are lower than in Porto. This pollutant can spread to other rooms, especially when ventilation is lacking, which is particularly concerning during colder seasons and at night. As around 70% of the time is spent at home, this can have a significant impact on human exposure to NO₂. Therefore, although Aveiro has low levels of NO₂ outdoors, its population may be exposed to much higher levels of this pollutant than the Porto population, a city with air quality issues, but predominantly using electric cookers. This finding emphasizes the need for the stricter regulation of NG use indoors to protect human health and also suggests a shift in human health protection policies from mere monitoring/control of outdoor air quality to a comprehensive assessment of human exposure, including exposure to indoor air quality. Full article