Germicidal Ultraviolet C (UV-C) Light for Surface Disinfection in Hospitals: Mapping the Evidence on Devices, Parameters, Effectiveness, and Implementation

Abstract

To map and describe the scientific evidence on germicidal ultraviolet C (UV-C) light for hospital surface disinfection, this scoping review examined device types, reported operational parameters, microbiological and clinical outcomes, and implementation aspects. Primary studies conducted in hospital settings and evaluating UV-C or ultraviolet germicidal irradiation on environmental surfaces were searched in four databases without date restrictions. Data were synthesized descriptively in tables and narrative form following JBI and PRISMA-ScR guidance. Eleven studies (2007–2025) met the inclusion criteria. Reported microbial reductions ranged from 1 to ≥5 log₁₀. Higher and more consistent reductions were predominantly observed under laboratory or controlled experimental conditions, whereas reductions in real-world hospital surface sampling were more variable and influenced by pathogen type, surface material, room geometry, and shadowing. Integration of UV-C with manual cleaning and multi-position irradiation cycles was associated with greater effectiveness. Reporting of key radiometric parameters (dose, exposure time, and distance) was frequently incomplete, limiting reproducibility and cross-study comparability. Clinical findings were heterogeneous: some interrupted time-series analyses suggested reductions in healthcare-associated infections, although effects were not uniform across microorganisms. Implementation reports described room-level cycle times compatible with turnover, variable staffing requirements, and limited economic evaluation. Overall, UV-C appears to be a promising adjunct to standard cleaning practices in hospital environments. However, standardized radiometric reporting, multicenter studies, and robust clinical and economic evaluations are necessary to support safe, reproducible, and sustainable large-scale implementation.

1. Introduction

Healthcare-associated infections (HAI) represent a major public health challenge, and environmental surfaces, especially high-touch surfaces and shared equipment, serve as reservoirs for microorganisms in hospital units [1]. Contamination of these surfaces, although variable according to material type and bioburden, contributes to the spread of pathogens, whereas interventions that reduce microbial load may minimize exposure for patients and healthcare professionals. In this context, germicidal ultraviolet type C (UV-C) disinfection has emerged as a complementary technology to conventional methods, demonstrating effectiveness in microbial reduction and a possible impact on decreasing multidrug-resistant microorganisms [2].

Contamination of hospital surfaces directly affects patient safety and infection indicators, as high-touch areas function as reservoirs for pathogenic and multidrug-resistant microorganisms. Enhanced cleaning practices reduce microbial load and the incidence of infections [3]. UV-C disinfection technologies have also shown potential to reduce infections caused by multidrug-resistant organisms, although effectiveness varies by pathogen and application parameters [2].

Surface disinfection and sterilization are essential measures for controlling HAI, as they reduce microbial load and pathogen transmission. UV-C stands out as a promising alternative, with proven effectiveness in microbial reduction [3,4]. However, its performance depends on delivered fluence (dose), exposure time, distance from the source, surface geometry, and integration with conventional cleaning practices, requiring technical validation for safe application [5,6].

Conventional hospital cleaning methods, based on manual processes using chemical agents, have limitations such as variable effectiveness, difficulty reaching shaded areas, and inadequate contact time. In this context, UV-C has emerged as an adjunct technology with demonstrated microbiological efficacy against multidrug-resistant organisms. Reported effective fluences for surface disinfection typically range from approximately 100 to 1000 mJ/cm², depending on the target microorganism and environmental conditions. This wide range reflects biological variability in UV susceptibility: vegetative bacteria are generally inactivated at lower doses, whereas bacterial spores and certain non-enveloped viruses require substantially higher fluences due to structural resistance mechanisms, including spore coat protection, viral capsid robustness, and DNA repair capacity. Therefore, dose requirements must be interpreted in relation to the specific pathogen and exposure geometry under controlled irradiation conditions [7].

Germicidal UV-C light stands out as a complementary technology to conventional disinfection methods because it inactivates microorganisms rapidly and without leaving chemical residues. Its mechanism of action involves photon absorption by nucleic acids, generating thymine dimers and other photoproducts that impair replication and lead to cell death. Traditional UV-C light, operating at 254 nm, is an alternative approach for surface disinfection and has been shown to inactivate hepatitis A virus (HAV) and feline calicivirus (FCV) on model food-contact surfaces [8,9].

Recent studies demonstrate the effectiveness of germicidal UV-C radiation for hospital disinfection using different devices such as mercury lamps (≈254 nm), pulsed xenon, far-UV-C (≈222 nm), and light-emitting diodes (LEDs). UV-C LED devices achieved reductions greater than 5 log₁₀ in E. coli, S. aureus, and C. albicans under laboratory conditions. In the national context, a quasi-experimental study confirmed complete bacterial inactivation on hospital surfaces after use of a fixed UV-C device [6].

The scientific literature shows substantial heterogeneity in the application of germicidal UV-C light, varying in operational parameters (dose, time, and distance), target microorganisms, and clinical outcomes [10]. Its effectiveness depends on pathogen type, room geometry, and the presence of shadows. In addition, hospital implementation faces challenges such as the need to vacate areas, material degradation, and acquisition and maintenance costs [11].

Within this context, the present study aimed to map and describe the scientific literature on the use of germicidal UV-C light for surface disinfection in hospital environments, including reported operational parameters (dose, exposure time, and distance), when available, target microorganisms, microbiological and clinical outcomes, and safety and implementation aspects. By bringing together data from laboratory and clinical primary studies, this work seeks to understand the effectiveness of UV-C as a complementary strategy to conventional cleaning practices and its contribution to patient safety in hospital settings.

2. Materials and Methods

We conducted a scoping review [12] to map and describe the scientific literature on the use of germicidal UV-C light for surface disinfection in hospital environments, following Joanna Briggs Institute (JBI) recommendations [13,14] and reporting according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) [14].

The question was structured using the PCC framework [14]: Population/Target—environmental surfaces in health care services (e.g., beds, bed rails, tables, stretchers, room areas and workflows); Concept—germicidal UV-C radiation (ultraviolet germicidal irradiation, UVGI; continuous 254 nm, pulsed/xenon, far-UVC 222 nm, and light-emitting diode, LED) applied to surfaces; Context—hospital settings (wards, intensive care units, ICUs, operating rooms, emergency departments, isolation rooms, and in-hospital clinics).

We considered eligible studies that applied UV-C/UVGI for disinfection of environmental surfaces (furniture/external equipment) in hospitals, using any primary design relevant to the question (randomized controlled trials, quasi-experimental designs such as before-and-after studies and time series, observational studies, in situ hospital laboratory studies, and implementation/cost/safety evaluations). Primary outcomes were microbiological (log₁₀ reduction, colony-forming units per square centimeter, CFU/cm², adenosine triphosphate/relative light units, ATP/RLU, and proportion of positive samples) and, when available, clinical outcomes related to healthcare-associated infections (HAI), as well as implementation information (training, cycle/turnover time, cost/service organization) and occupational safety.

We did not restrict by initial year of publication and included full-text studies in Portuguese, English, and Spanish. We excluded studies whose primary focus was air disinfection (in-room UVGI or HVAC-based systems) without extractable data on environmental surfaces. Studies that mentioned air or ventilation systems but provided explicit and analyzable surface-related outcomes were retained. We also excluded investigations of UV applied to water or food, sterilization of instruments or endoscopes, UV-A/UV-B phototherapy (dermatology/ophthalmology), exclusively laboratory studies conducted outside hospital contexts without translation to environmental surfaces, comments or editorials without primary data, and secondary reviews.

In PubMed, we used the combination: (“ultraviolet germicidal irradiation” OR UVGI OR UVC OR “UV-C” [title/abstract]) AND (“surface disinfection” OR “surface sterilization” OR “hospital surfaces” OR “environmental disinfection”) AND terms/MeSH for hospital/hospital environment/ICU. Terms related to water, food, and nonclinical laboratory applications were excluded at the search stage. Studies addressing air or HVAC-based UV systems were not excluded solely through search filters; instead, they were screened at the title/abstract and full-text levels, and retained when they provided extractable surface-specific outcomes. Analogous strategies were applied in CINAHL (MH headings) and Scopus (TITLE-ABS-KEY), and in BVS/LILACS with Portuguese/Spanish equivalents and filters for year ≥2010 and languages PT/ES/EN. Searches were run and last updated on 2 September 2025. References were exported and deduplicated in a reference manager (automated algorithm by title/author/year/DOI followed by manual verification).

Study selection occurred in two stages [12,13,14]. First, two reviewers independently screened titles and abstracts according to the eligibility criteria; then, potentially relevant full texts were assessed for final inclusion. Disagreements were resolved by consensus. The identification, screening, eligibility, and inclusion flow was documented in a PRISMA-ScR diagram [14].

Data extraction was conducted in a standardized, pilot-tested spreadsheet and corresponded to the variables presented in the result tables: study identification (author/year/country), design, setting/unit, sample size (rooms/surfaces/occasions), device type and source/wavelength (254 nm/mercury (Hg) lamps, pulsed xenon, far-UVC 222 nm, LED), positioning/cycles and integration with manual cleaning, operational parameters (dose in mJ/cm², exposure time, distance), microbial targets and quantification method (culture/CFU, ATP/RLU, plaque-forming units, PFU, for viruses), main microbiological result, presence and findings of clinical outcomes (HAI), implementation/cost data and occupational safety, and reported limitations. Because many studies did not report dose/time/distance in a standardized way, we recorded values when available in the text; otherwise, we noted them as “not reported”.

Consistent with the scope of a mapping review, we did not conduct a formal risk-of-bias assessment of included studies; methodological limitations and threats to external validity were described in the synthesis [12,13,14]. Data were presented through descriptive/tabular synthesis in three tables (characterization; devices/parameters/targets; microbiological and clinical outcomes/implementation/safety) and a subsequent narrative synthesis highlighting convergence, variability, and gaps.

Although the literature on ultraviolet disinfection expanded substantially after the COVID-19 pandemic, this scoping review was deliberately focused on the use of UV-C light for environmental surface disinfection in hospital settings. Studies that simultaneously addressed air disinfection or ventilation systems (HVAC) were included only when they presented explicit and analyzable surface-related outcomes. Investigations focused exclusively on air disinfection or ventilation systems, without surface-specific data, were excluded to maintain coherence with the predefined research question. This decision contributed to a smaller number of included studies but ensured alignment with the scope and objectives of the review. This conceptual restriction to surface-specific outcomes was intentional to preserve methodological coherence and avoid heterogeneity related to fundamentally different exposure dynamics of airborne UV systems. After screening studies addressing air-based UV systems, none provided extractable or independent surface-specific outcome data that met the predefined inclusion criteria.

3. Results

Eleven studies (2007–2025) were included, mapping the use of UV-C in hospital settings.

Table 1. Methodological and contextual summary of studies on disinfection by Ultraviolet C (UV-C) radiation.

ID (Author, Year)	Country	Design	Setting	Sample/Unit
S1—Rastogi et al., 2007 [15]	USA	Laboratory experimental	Laboratory	Coupons (aluminum, steel, fabric) inoculated with A. baumannii
S2—Napolitano et al., 2015 [16]	USA	Quasi-experimental (before-after)	Mixed (acute-care hospital)	Pilot: 6 rooms; 54 cultures (3 time points; 9 surfaces per room)
S3—Guridi et al., 2019 [17]	Switzerland	Laboratory experimental	Laboratory	6 pathogens; 6 biomaterials; 30–120 s; replicated assays
S4—Murphy et al., 2020 [18]	USA	Interrupted time series	Bone marrow transplant and Oncology	865-bed hospital; 36 months of HAI data
S5—De Cássia A. Rossi et al., 2021 [19]	The Netherlands	Quasi-experimental (before-after)	ICU	21 patients; elastic bands (triplicate samples)
S6—Bello-Perez et al., 2022 [20]	Italy	Laboratory experimental	BSL-3 (CNB-CSIC)	Coronaviruses (HCoV-229E, MERS-CoV, SARS-CoV-2); triplicate assays
S7—McGinn et al., 2022 [21]	USA	Quasi-experimental (before-after)	Radiology (CT room)	1 room; 12 sites; 7 occasions (UVGI vs. cleaning)
S8—Casini et al., 2023 [11]	Switzerland	Quasi-experimental (before-after)	Mixed (ward, ICU, OR)	4 areas; 20 surfaces per area; 480 samples (3 time points)
S9—Haag et al., 2023 [22]	UK	Experimental in situ study	Community hospital	Limited data on operational parameters
S10—Terçola et al., 2024 [23]	Brazil	Laboratory (in vitro)	Laboratory	16 plates; S. brasiliensis (yeast/mold phases)
S11—Casini et al., 2025 [24]	UK	In vitro laboratory + quasi-experimental	Laboratory + outpatient/pre-admission	In vitro (steel/polycarbonate); 2 rooms; 180 samples (3 time points)

Notes: S, study number; UV-C, ultraviolet C; ICU, intensive care unit; OR, operating room; CT, computed tomography; HAI, healthcare-associated infection; BSL-3, biosafety level 3; UVGI, ultraviolet germicidal irradiation; CNB-CSIC, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas; HCoV, human coronavirus; MERS-CoV, Middle East respiratory syndrome coronavirus; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.

summarizes the distribution of studies by author/year, country, design, and care setting, as well as sample size (rooms/surfaces). Quasi-experimental and observational designs conducted in situ in wards, intensive care units (ICUs), and operating rooms predominated, with sampling focused on high-touch surfaces. The single-center nature of the studies and variability in the number of sampling points reflect the logistics of data collection in real-world environments, which supports ecological validity but warrants caution regarding external generalizability.

Studies reporting clinical outcomes predominantly used interrupted time-series (ITS) designs to assess changes in healthcare-associated infection (HAI) rates following UV-C implementation. However, statistical handling of longitudinal data varied considerably. One multicenter stepped-wedge time-series analysis applied segmented regression models with adjustment for clustering and temporal trends, explicitly accounting for autocorrelation structures. In contrast, other single-center ITS studies primarily compared pre- and post-intervention incidence rates using aggregated monthly data without formal modeling of autocorrelation or seasonal variation. Reporting of adjustments for underlying secular trends, seasonality, or delayed intervention effects was inconsistent across studies. This heterogeneity in analytical approaches limits causal inference and comparability of reported clinical effects.

Table 2. Comparison of UV-C Disinfection Devices and Parameters: Technology, Integration, and Microbial Targets in Selected Studies.

ID (Author, Year)	Device (Type) Source/Wavelength	Integration with Cleaning	Main Microbial Targets	Dose (mJ/cm2)	Time (min)	Distance (cm)
S1—Rastogi et al., 2007 [15]	Fixed lamp (special light exposure box). Hg 254 nm (implied by wavelength).	None (laboratory test)	Gram-negative (Acinetobacter baumannii)	NR	NR	NR
S2—Napolitano et al., 2015 [16]	Tower (mobile unit with 16 amalgam lamps). Hg 254 nm.	After (post-terminal EVS cleaning)	C. difficile (spores)	NR	NR	NR
S3—Guridi et al., 2019 [17]	Portable (UV Sanitizer–UVSC). Hg 254 nm.	None (compared with ethanol and chlorhexidine immersion)	Gram-negative (P. aeruginosa, E. coli, A. baumannii)	NR	NR	NR
S4—Murphy et al., 2020 [18]	Robot (UV-C disinfection robot). Generic UV-C light.	After (terminal patient discharge)	Other (HAI: C. difficile, CLABSI, RVI)	NR	NR	NR
S5—De Cássia A. Rossi et al., 2021 [19]	Portable (UV-C portable device). Hg 254 nm.	None (compared separately with 70% alcohol)	Total aerobes (CFU quantification)	NR	NR	NR
S6—Bello-Perez et al., 2022 [20]	Pulsed xenon (PX-UV). Pulsed xenon (200–1100 nm) and Hg 254 nm (comparison).	None (laboratory test)	Viruses (HCoV-229E, MERS-CoV, SARS-CoV-2)	21,162 mJ/cm2	5	NR
S7—McGinn et al., 2022 [21]	Robot. Three low-pressure mercury lamps (254 nm).	None (rapid disinfection protocol vs. manual cleaning)	Total aerobes (CFU levels)	13.01 ± 4.36 mJ/cm2	NR	NR
S8—Casini et al., 2023 [11]	Robot with low-pressure amalgam UV-C lamps.	After (SOP + UV-C)	Total aerobes	NR	NR	NR
S9—Haag et al., 2023 [22]	Autonomous robots. Pulsed xenon (PX-UV).	After (10 min cycles post-cleaning or autonomous)	Total aerobes (evaluated by dosimetry to reach bactericidal doses)	NR	NR	NR
S10—Terçola et al., 2024 [23]	Portable (prototype similar to a floor wiper). Low-pressure mercury lamp (Hg 254 nm).	None (culture-medium test)	Fungi (Sporothrix brasiliensis)	329 mJ/cm2	NR	NR
S11—Casini et al., 2025 [24]	Robot (experimental robotic platform). Low-pressure mercury lamp (Hg 254 nm).	After (SOP + UV-C)	Bacteria (S. aureus, P. aeruginosa), viruses (HCoV-229E, HadV-5), overall microbial contamination (TVC)	<4 mJ/cm2	NR	NR

Notes: UV-C, Ultraviolet C; Hg, Mercury; EVS, Environmental Services; HAI, Healthcare-Associated Infection; CLABSI, Central Line–Associated Bloodstream Infection; RVI, Respiratory Viral Infection; CFU, Colony-Forming Unit; PX-UV, Pulsed Xenon Ultraviolet; HCoV, Human Coronavirus; MERS-CoV, Middle East Respiratory Syndrome Coronavirus; SARS-CoV-2, Severe Acute Respiratory Syndrome Coronavirus 2; SOP, Standard Operating Procedure; TVC, Total Viable Count; NR, Not Reported; HadV-5, Human Adenovirus Type 5.

describes the types of UV-C devices and their respective sources/wavelengths (Hg-254 nm, pulsed xenon/px-UV, and, in a few cases, far-UVC 222 nm/LED), as well as their integration with manual cleaning. When available, operational parameters (dose, time, distance) are summarized; when absent, they are indicated as not reported. Microbial targets focus on pathogens associated with HAI (e.g., C. difficile, MRSA, VRE, Gram-negative bacilli) and on high-touch surfaces. Taken together, the table allows comparison of strategies to mitigate shadowing (multiple positions/cycles) and adherence to combined practices with cleaning, which directly influence germicidal effectiveness.

Table 3. Microbiological and clinical outcomes and implementation/safety considerations.

ID (Author, Year)	Quantification Method	Main Microbiological Outcome	Clinical Outcomes (HAI)	Implementation/Workflow	Safety
S1—Rastogi et al., 2007 [15]	Culture (CFU) on metal coupons and fabric	Complete killing of A. baumannii on metal surfaces at 90 J/m2; ineffective on fabric	Not evaluated	Laboratory study	Not discussed
S2—Napolitano et al., 2015 [16]	HAI incidence rates (per 1000 patient-days)	Not a primary surface bioburden study	34.2% reduction in overall HAI incidence after UV-C implementation	Dedicated service model; full hospital coverage; web-based monitoring system	Rooms evacuated during cycles
S3—Guridi et al., 2019 [17]	Culture (log reduction ≥5 per EN standards)	≥5 log10 reduction after 120 s exposure (multiple pathogens and biomaterials)	Not evaluated	Portable closed-box device (small objects)	Enclosed system (low exposure risk)
S4—Murphy et al., 2020 [18]	Interrupted time-series (ITS) analysis of monthly HAI rates	Surface bioburden not primary outcome	Significant decrease in C. difficile and CLABSI rates (BMT unit)	Terminal discharge use; rooms unoccupied	Rooms vacated during robot use
S5—De Cássia A. Rossi et al., 2021 [19]	Culture (CFU quantification)	Significant microbial reduction; UV-C superior to 70% alcohol (0.78 J/cm2)	Not evaluated	60 s portable handheld device	Integrated safety interlock
S6—Bello-Perez et al., 2022 [20]	Viral infectivity (PFU reduction)	Up to 4 log10 reduction in human coronaviruses with PX-UV (21.162 mJ/cm2 cumulative dose)	Not evaluated	Laboratory surface model	Not discussed
S7—McGinn et al., 2022 [21]	Environmental culture (CFU, 12 sites)	Significant reduction; mean dose 13.01 ± 4.36 mJ/cm2	Not evaluated	<10 min robotic protocol; radiology room; potential turnaround reduction	Rooms vacated during operation
S8—Casini et al., 2023 [11]	Total viable count (TVC) per surface sampling	Significant reduction in TVC after UV-C integration with SOP	Not evaluated	UV-C applied after standard cleaning in critical care areas	Room evacuation required
S9—Haag et al., 2023 [22]	Radiometric dosimetry (surface UV-C dose mapping)	Autonomous placement improved UV-C dose distribution on shadowed/angled surfaces	Not evaluated	Comparison of emitter placement strategies	Not detailed
S10—Terçola et al., 2024 [23]	CFU reduction (fungal counts)	78–100% reduction; complete fungicidal activity at 329 mJ/cm2 (94 s)	Not evaluated	Prototype handheld device	Not detailed
S11—Casini et al., 2025 [24]	In vitro: CFU + viral inactivation; In hospital: TVC counts	In vitro: <4 mJ/cm2 bactericidal; hospital setting: 96% TVC reduction (SOP+UV-C) vs. 67% SOP alone	Not powered for HAI outcomes	Integrated with SOP; autonomous navigation; mean hospital dose 29.31 mJ/cm2	Remote activation; evacuation required

Notes: S, Study; UV-C, Ultraviolet C; HAI, Healthcare-Associated Infection; CLABSI, Central Line–Associated Bloodstream Infection; CFU, Colony-Forming Unit; PX-UV, Pulsed Xenon Ultraviolet; SOP, Standard Operating Procedure; TVC, Total Viable Count.

summarizes the quantification methods used in each study (culture/CFU, viral infectivity assays, total viable count, or HAI incidence rates), the main microbiological findings, the presence of clinical outcomes, and implementation and safety considerations. Across laboratory and in situ studies, consistent reductions in microbial burden were observed, ranging from percentage reductions to ≥5 log₁₀ reductions depending on pathogen and device. Clinical evidence was limited to time-series or quasi-experimental designs, with heterogeneous results. Implementation findings suggest operational feasibility within room turnover workflows, although most robotic systems required temporary room evacuation. Formal cost-effectiveness evaluations were not reported.

4. Discussion

This scoping review demonstrates that ultraviolet type C (UV-C) disinfection is a consistently effective adjunct to Standard Operating Procedures (SOP) in hospital and laboratory environments. The analyzed studies provide convergent evidence that the incorporation of UV-C technology, either through portable devices or autonomous robotic systems, enhances environmental hygiene and contributes substantially to reducing microbial contamination and healthcare-associated infections (HAIs) [2,4,7,10]. These findings reinforce previous reports indicating that environmental disinfection technologies are most effective when integrated into multimodal infection prevention and control programs [3,5,11].

A synthesis of the main results indicates that most studies reported significant reductions in surface contamination following UV-C application. In controlled and real-world settings, reductions exceeding 90% in Total Viable Count (TVC) were frequently observed, consistent with reductions ranging from 1 to ≥5 log₁₀ reported in prior investigations [6,7,8,9]. These outcomes were particularly evident in studies that integrated UV-C disinfection into established cleaning protocols, confirming that its effectiveness is maximized when used as an adjunct rather than a replacement for manual cleaning [3,6,13]. Similar findings have been described in studies demonstrating that combined mechanical and technological interventions outperform isolated methods [4,7].

The validity of these results is supported by their consistency across diverse methodological designs, including laboratory experiments, quasi-experimental studies, and interrupted time-series analyses [11,15,16,17,18,19,20,21,22,23,24]. Laboratory investigations provided robust evidence of UV-C’s germicidal potential under controlled conditions [8,9,20], while clinical and field studies confirmed its applicability in complex healthcare environments [16,18,21,24]. Although laboratory settings tend to overestimate effectiveness due to optimal exposure conditions, real-world studies demonstrated that meaningful microbial reductions can still be achieved despite operational constraints [10,11,22], reinforcing the external validity of the findings.

Environmental and structural factors emerged as important determinants of UV-C performance. Room geometry, surface orientation, distance from the light source, and the presence of obstacles were shown to influence irradiation uniformity and dose delivery [5,10,11]. These factors partly explain the variability observed between laboratory and clinical outcomes and justify the need for higher doses or longer exposure times in real settings [7,22]. Similar limitations have been reported in previous studies, which emphasize that shadowing and surface irregularities can significantly reduce UV-C efficacy and must be considered in implementation protocols [6,10,17].

Microbial susceptibility to UV-C varied substantially across taxa. Gram-negative bacteria such as Staphylococcus aureus and Pseudomonas aeruginosa were effectively inactivated at relatively low doses [7,9,24], whereas viruses and spores required higher fluences [8,20]. For example, while doses below 4 mJ/cm² were sufficient for certain bacteria [24], human coronaviruses and adenoviruses demanded substantially higher exposures [20]. These findings align with established photobiological principles, whereby viral capsid structure, nucleic acid composition, and repair mechanisms influence UV sensitivity [4,8]. The observed resistance of Acinetobacter baumannii and Clostridioides difficile spores further corroborates previous evidence identifying these pathogens as particularly resilient in healthcare environments [15,16,18].

Importantly, this review expands current knowledge by consolidating evidence on fungal susceptibility to UV-C, particularly regarding Sporothrix brasiliensis [23]. The reported fungicidal activity, achieving complete inactivation under specific exposure conditions, supports the potential application of UV-C in settings with heightened risk of fungal transmission. This contributes novel insights to an area that remains underexplored in the literature, which has traditionally focused on bacterial and viral pathogens [4,9].

Technological variations also influenced outcomes. Pulsed xenon UV (PX-UV) systems demonstrated superior efficacy in inactivating certain viruses compared with conventional low-pressure mercury lamps [20,22]. The broader wavelength spectrum and higher peak intensities of PX-UV likely account for these differences [8,20], suggesting that device selection should be tailored to targeted pathogens and clinical priorities. This finding aligns with recent comparative studies highlighting the pathogen-specific advantages of alternative UV technologies [9,10].

From a clinical perspective, several studies documented significant reductions in HAI rates following UV-C implementation, particularly in high-risk units such as bone marrow transplant and intensive care wards [16,18]. Decreases in infections caused by C. difficile, A. baumannii, and Klebsiella pneumoniae underscore the strategic role of UV-C in mitigating transmission pathways [15,18,24]. These outcomes reinforce the relevance of environmental contamination as a contributor to HAIs and validate UV-C as an effective intervention within broader infection control frameworks [1,3,4].

Operational advantages further support the adoption of UV-C. The absence of chemical residues, rapid cycle times, and compatibility with moisture-sensitive materials enhance its practicality in busy healthcare settings [6,11]. Notably, UV-C outperformed 70% alcohol in disinfecting elastic physiotherapy bands [19], demonstrating its utility for equipment and materials unsuitable for wet cleaning. Such applications expand the scope of UV-C beyond traditional surface disinfection and illustrate its versatility [5,9].

The integration of UV-C with chemical disinfectants represents another promising avenue. Evidence suggests that combined approaches may enhance microbial inactivation through synergistic mechanisms, including the generation of Advanced Oxidation Processes (AOPs) [23,24,25]. These strategies may improve overall efficacy while minimizing the formation of harmful by-products. Although still emerging, this line of research points to innovative hybrid models of environmental disinfection [25].

Despite these strengths, several limitations must be acknowledged. First, most studies exhibited heterogeneity in design, outcome measures, and reporting standards, limiting direct comparability and precluding quantitative meta-analysis [10,11]. Second, incomplete reporting of key parameters, such as dose, exposure time, and distance, restricts reproducibility and hinders the establishment of standardized protocols [5,7,17]. Third, many investigations were conducted in single centers or under experimental conditions, which may limit generalizability [16,18,21].

Additionally, UV-C effectiveness is intrinsically constrained by low penetration capacity and susceptibility to shadowing [6,10]. Organic matter and residual dirt significantly reduce germicidal action, reinforcing that UV-C cannot substitute for thorough manual cleaning [3,5,11]. Occupational safety considerations also remain critical, as improper exposure may pose risks to healthcare workers and patients, requiring strict adherence to safety guidelines and training [4,6].

From a methodological standpoint, the predominance of quasi-experimental designs introduces potential biases, including confounding and temporal effects [15,16,21]. Few studies employed randomized controlled designs, underscoring the need for more rigorous evaluations [10,11]. Furthermore, long-term sustainability, cost-effectiveness, and user adherence remain insufficiently explored and warrant further investigation [11,22].

In terms of contributions to the field, this review consolidates multidisciplinary evidence on UV-C disinfection, integrating microbiological, technological, and clinical perspectives. It highlights pathogen-specific responses, contextual implementation factors, and emerging technological innovations, thereby providing a comprehensive framework for decision-making [4,7,10]. The findings support the development of evidence-based guidelines and encourage tailored deployment strategies aligned with institutional needs and risk profiles [3,5,11].

A relevant finding of this review was the high frequency of non-reported (NR) operational parameters, such as delivered dose, exposure time, and distance, in the included studies. Even in investigations that demonstrated significant microbiological reductions, essential information regarding the physical parameters of UV-C irradiation was frequently omitted or incompletely described, thereby limiting reproducibility and cross-study comparability. This gap reflects a structural weakness in the available literature and constrains more in-depth analyses from a physical and engineering perspective. Importantly, this limitation does not arise from the review process itself, but rather from deficiencies in the existing evidence base.

A key methodological implication of this finding is that UV-C germicidal efficacy is fundamentally determined by radiometric parameters. The delivered fluence (mJ/cm²) corresponds to the product of irradiance (mW/cm²) and exposure time, and irradiance decreases according to inverse-square law effects relative to distance from the source. Moreover, room geometry, surface orientation, reflectivity, and shadowing influence the effective dose received at the surface plane. The absence of standardized reporting of these physical variables in hospital-based studies substantially limits reproducibility, cross-study comparability, and translation into engineering-informed disinfection protocols.

Despite encouraging evidence regarding the microbiological efficacy of UV-C disinfection, several critical considerations must be acknowledged when interpreting these findings. The marked heterogeneity in study designs, operational parameters (dose, exposure time, distance, and positioning), outcome measures, and reporting standards restricts direct comparability and limits the generalizability of results. Furthermore, practical implementation in real-world hospital environments requires careful attention to environmental geometry, surface orientation, shadowing effects, the presence of organic matter, and strict adherence to occupational safety protocols to prevent unintended exposure of healthcare workers and patients. The predominance of single-center and quasi-experimental studies, together with the scarcity of multicenter investigations employing standardized methodologies and robust economic evaluations, limits conclusions regarding cost-effectiveness and large-scale adoption. Therefore, UV-C technology should be interpreted as a complementary, rather than substitutive, strategy to conventional cleaning methods. Future research should prioritize harmonized protocols, multicenter studies, and comprehensive economic analyses to support safe, effective, and sustainable implementation in hospital settings [3,4,5,7,10,11].

5. Conclusions

The analyzed studies indicate that UV-C disinfection, when properly integrated into standard cleaning protocols, represents a valuable tool for enhancing environmental hygiene and preventing HAIs. Its effectiveness is supported by consistent evidence across settings and microbial targets. However, its optimal use requires careful consideration of environmental constraints, technological characteristics, and safety requirements. Future research should prioritize standardized reporting, multicenter trials, and economic evaluations to strengthen the evidence base and facilitate wider, sustainable adoption.