Introduction. Microbial contamination of industrial, office, and residential premises is a widespread biological factor. To reduce microbial contamination, various ultraviolet (UV) radiation sources based on mercury lamps and light-emitting diodes (LEDs) are used, with germicidal efficiency reaching up to 99.9% at significantly lower energy consumption. According to the Order of the Ministry of Health of Ukraine dated 06.05.2021 No. 882, germicidal UV radiation sources are classified into open-type irradiators and closed-type irradiators (recirculators), with shielded UV sources occupying an intermediate position. Each type of irradiator has specific technical advantages and disadvantages in application. Disadvantages of open-type UV irradiators include insufficient efficiency in shaded areas in the presence of optical obstructions within the premises, as well as the need to control risks for human skin and eyes. For recirculators, disadvantages include the absence of direct UV irradiation of surfaces and their disinfection only as a side effect of air purification, along with the risk of ozone formation when using mercury lamps. Therefore, the creation of an effective germicidal system for improving premises to the recommended international cleanliness standards, combining the technical advantages of open- and closed-type UV sources while avoiding their disadvantages, is an urgent task of modern hygiene.
Aim of the study. To determine the effectiveness of a germicidal system combining open- and closed-type ultraviolet radiation sources for improving office and industrial premises.
Materials and methods. The germicidal effectiveness of the ultraviolet irradiator (UVI) system was studied in laboratory-classroom premises of Kyiv National University of Construction and Architecture (KNUCA, MES of Ukraine) and in open space type office and partitioned offices of LLC “Naftogaz CT” (Kyiv). The UVI system included open-type irradiators LED UVC T5-5W-275NM and recirculators e.uv.115.1x12W/Ultra UV-2-60 (Ukraine). The intensity of UV radiation at the level of work desks during UVI operation was 1 mW/m², which met biological safety requirements according to DSTU EN 62471:2017 for an 8-hour exposure. Recirculators were installed in accordance with manufacturer’s instructions and recommendations of the Public Health Center of the Ministry of Health of Ukraine (2020). Microbial contamination of desk surfaces was assessed by colony-forming units (CFU)/dm² using swab sampling. Samples were collected immediately before UVI installation and after 2.5–3.0 months of exposure. The studied indicators included the total count of microorganisms (TC) and the presence of Staphylococcus aureus (SA), determined using test systems by R-Biopharm AG (Germany). Sample incubation in a thermostat was conducted according to manufacturer’s instructions. General assessment of microbial contamination of premises was carried out in accordance with the SBM-2015 standard. Statistical reliability was analyzed using licensed Microsoft Office Excel 2007/Windows and STATISTICA 6.0 software.
Results and discussion. The initial level of total microbial contamination in office and laboratory premises before UVI installation ranged from 31 CFU/dm² (partitioned office of LLC “Naftogaz CT”) to 83 CFU/dm² (open space type office of LLC “Naftogaz CT”). Operation of the UVI system in KNUCA premises reduced CFU levels of microflora by 4.4 times, reaching the criterion of “absence of contamination” (<20 CFU/dm²). In the open space type office, UVI system use decreased the total microflora by 9.2 times, from 83 CFU/dm² to 9 CFU/dm². In the partitioned office, a 10.4-fold reduction was observed, from 52 CFU/dm² to 3 CFU/dm². In both cases, during UVI system operation, offices met the criterion of “absence of contamination,” whereas in premises without UVI the CFU levels practically did not decrease and contamination remained at the initial level according to SBM-2015 criteria.
Conclusions. Microbial contamination levels in office and laboratory premises ranged from 31 CFU/dm² (partitioned office) to 83 CFU/dm² (open space type office). The use of the UVI system in laboratory and office premises reduced CFU levels of microflora by 4.4–10.4 times; the premises met the criterion of “absence of contamination” (<20 CFU/dm²) according to the European SBM-2015 standard. In premises without UVI, CFU levels remained practically unchanged throughout the UV exposure period. In areas of high occupancy, when the area and volume per person are significantly below normative values, the presence of Staphylococcus aureus at 1–2 CFU/dm² may be observed. Use of the combined UVI system led to the elimination of Staphylococcus aureus in laboratory premises throughout the study period. There is a need to implement the requirements of the European SBM-2015 standard regarding microbial contamination control for non-medical premises to improve workplace conditions.
Keywords: germicidal ultraviolet radiation sources, microbial contamination, office and industrial premises, improvement of the industrial environment.
References
- Baudet A, Guillaso M, Grimmer L, Regad M, Florentin A. Microbiological contamination of the office environment in dental and medical practice. Antibiotics. 2021;10(11):1375. DOI: https://doi.org/10.3390/antibiotics10111375
- Skora Ju, Gutarowska B, Stępien L, Otlewska A, Pielech-Przybylska K. The evaluation of microbial contamination in the working environment of tanneries. Med Pr Work Health Saf. 2014;65(1):15-32. DOI: https://doi.org/10.13075/mp.5893.2014.005
- Nazarenko VI, Cherednichenko IM, Leonov YuI, Pochta VN, Shevchenko AV, Burdeina NB, Yarygin AV. Hygienic principles of using bactericidal ultraviolet monochrome LED irradiators of the open type for premises air disinfecting. Ukrainian Journal of Occupational Health. 2022;18(3):216-23. DOI: https://doi.org/10.33573/ujoh2022.03.216
- Mohammed OAM. Surface microbial contamination and air quality before and after regular cleaning procedures. Atmosphere. 2023;14(2):352. DOI: https://doi.org/10.3390/atmos14020352
- Won DH, Huh EH, Jeong HC, Moon KW. Microbiological contamination in office buildings by work space structure. Journal of Environmental Health Sciences. 2012;38(3):213-22. DOI: https://doi.org/10.5668/JEHS.2012.38.3.213
- Marushchak MI, Korobko LR, Nychyk BV, Chyzhyshyn BZ, Myalyuk OP. [Structure of respiratory morbidity and the role of urbanization in the prevalence of this group of diseases]. Health & Education. 2024;2:62-74. Ukrainian. DOI: https://doi.org/10.32782/health-2024.2
- On approval of the State sanitary rules and regulations “Hygienic requirements for the placement, arrangement, equipment and operation of perinatal centers”, Order Ministry of Health of Ukraine No. 55 [Internet]. 2012 Jan 26; Registered with the Ministry of Justice of Ukraine No. 248/20561, 2012 Feb 02 [cited 2025 Aug 09]. Available from: https://zakon.rada.gov.ua/laws/show/z0248-12#Text
- On approval of hygienic regulations for permissible content of chemical and biological substances in the workplace air, Order Ministry of Health of Ukraine No. 1596 [Internet]. 2020 Jul 14; Registered with the Ministry of Justice of Ukraine No. 741/35024, 2020 Aug 03 [cited 2025 Aug 09]. Available from: https://zakon.rada.gov.ua/laws/show/z0741-20#Text
- Leonov YuI, Nazarenko VI, Myshchenko I. The problem of hygienic standardization of air concentration of microorganisms in office premises. Ukrainian Journal of Occupational Health. 2022;18(2):147-54. DOI: https://doi.org/10.33573/ujoh2022.02.147
- Institute of Building Biology + Sustainability IBN. Standard of Building Biology Testing Methods: SBM–2015 (acting from July 2008) [Internet]. Germany; 2015 [cited 2025 May 15]. Available from: https://buildingbiology.com/building-biology-standard/.
- Lang D. The spectrum of mercury low pressure lamps for disinfection. LinkedIn. [Internet]. 2020 Apr 23 [cited 2025 Apr 10]. Available from: https://www.linkedin.com/pulse/spectrum-mercury-low-pressure-lamps-disinfection-dieter-lang
- Nazarenko VI, Leonov YuI, Glyva VA, Burdeina NB, Cherednichenko IM, Pochta VN, Golubeva AO. The influence of UV-LED lamp radiation on indicators of microflora in university auditoriums. Ukrainian Journal of Occupational Health. 2023;19(1):42-50. DOI: https://doi.org/10.33573/ujoh2023.01.042
- Nazarenko VI, Leonov YuI, Cherednichenko IM, Glyva VA, Burdeina NB, Shabashkevich BH, Pochta IV. [Application of bactericidal ultraviolet monochrome LED irradiators for air and surface disinfection in premises: methodical recommendations]. Approved by the National Academy of Medical Sciences of Ukraine 2023 Nov 14. Kyiv; 2023. 12 p. Ukrainian.
- Green A, Popović V, Warriner K, Koutchma T. The efficacy of UVC LEDs and low-pressure mercury lamps for the reduction of Escherichia coli O157:H7 and Listeria monocytogenes on produce. Innovative Food Science & Emerging Technologies. 2020;64:102410. DOI: https://doi.org/10.1016/j.ifset.2020.102410
- Nichia LED/LD [Internet]. Alternative technologies to low-pressure germicidal mercury lamps for water disinfection applications; 2024 Oct 22 [cited 2025 May 15]. Available from: https://led-ld.nichia.co.jp/en/blog/m000024.html
- State Standard of Ukraine. DSTU EN 62471:2017. Photobiological safety of lamps and lamp systems (EN 62471:2008, IDT; IEC 62471:2006, MOD) [Internet]. Kyiv; 2018 [cited 2025 May 15]. 33 p. Available from: http://online.budstandart.com/ua/catalog/doc-page?id_doc=74817
- On approval of sanitary and anti-epidemic rules and norms for the use of ultraviolet bactericidal radiation, Order Ministry of Health of Ukraine No. 882 [Internet]. 2021 May 06; Registered with the Ministry of Justice of Ukraine on 28.07.2021 No. 978/36600 [cited 2025 Jul 20]. Available from: https://zakon.rada.gov.ua/laws/show/z0978-21#Text
- Directive 2006/25/EC of the European Parliament and of the Council of 5 April 2006 on the minimum health and safety requirements regarding the exposure of workers to risks arising from physical agents (artificial optical radiation). Official Journal of the European Union [Internet]. 2006 Apr 04 [cited 2025 Jun 09];L 114/38. Available from: https://eurlex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2006:114:0038:0059:en:PDF
- ACGIH. Threshold Limit Values for Chemical Substances and Physical Agents & Biological Exposure Indices [Internet]. Cincinnati: Signature Publications; 2019 [cited 2025 Jun 09];308 p. Available from: https://riesgosygestion.com/wp-content/uploads/2019/06/tlv2019_entire-book.pdf
- Public Health Center of the Ministry of Health of Ukraine [Internet]. Recommendations on the use of ultraviolet irradiation (UV) for disinfection; 2020 Jun 25 [cited 2025 Jun 09]. Available from: https://phc.org.ua/news/rekomendacii-schodo-vikoristannya-ultrafioletovogo-oprominennya-uf-dlya-dezinfekcii
- GOST R 8.760-2011. State system for ensuring the uniformity of measurements. Measurement of energy and effective characteristics of bactericidal ultraviolet irradiators. Measurement method [Internet]. 2019 [cited 2025 Jun 09]. Available from: https://vsegost.com/Catalog/53/53852.shtml
- State Standard of Ukraine. DSTU-N RMH 70:2007. Metrology. Characteristics of ultraviolet radiation of bactericidal irradiators. Method of measurement (RMH 70-2003, IDT) [Internet]. 2007 [cited 2025 Jun 09]. Available from: https://online.budstandart.com/ua/catalog/doc-page?id_doc=53260
- On approval of the State sanitary norms and rules “Hygienic classification of labor by indicators of harmfulness and danger of production environment factors, severity and intensity of labor process", Order Ministry of Health of Ukraine No. 248 [Internet]. 2014 Apr 08 [cited 2025 Aug 09]. Available from: https://zakon.rada.gov.ua/laws/show/z0472-14#Text
- Surmasheva OV, Chernysh OO, Borovyk MP. Evaluation of the effectiveness of indoor air disinfection using a bactericidal ultraviolet recirculator. In: Ecology and Medicine: Proceedings of the All-Ukrainian Scientific-Practical Conference; 2021 March 18–19; Kyiv [Internet]. Kyiv; 2021 [cited 2025 May 15]. p. 285-9. Available from: https://health.gov.ua/wp-content/uploads/2024/03/ecology-and-medicine-conference-proceedings-2021.pdf
- Lin C, He Ju, Liu Z, Liang Q. Effectiveness, safety, and challenges of UVC irradiation in indoor environments: A decade of review and prospects. Building and Environment. 2025;276:112868. DOI: https://doi.org/10.1016/j.buildenv.2025.112868
- Kovalenko NI, Zamazii TM. Sanitary Microbiology: [Methodological guidelines for the discipline Microbiology, Virology and Immunology] [Internet]. Kharkiv: KhNMU; 2021 [cited 2025 Aug 09]. 48 p. Ukrainian. Available from: https://repo.knmu.edu.ua/server/api/core/bitstreams/0fdad0d7-3150-4e98-86af-fe4ea42e7ee2/content
- State Standard of Ukraine. DSTU B EN ISO 7730:2011. Ergonomics of the thermal environment. Analytical determination and interpretation of thermal comfort based on calculation of PMV and PPD indices and local thermal comfort criteria (EN ISO 7730:2005, IDT) [Internet]. 2012 [cited 2025 Apr 01]. Available from: https://online.budstandart.com/ua/catalog/doc-page.html?id_doc=28002
- State sanitary rules and norms DSANPiN 3.3.2-007-98. Hygienic requirements for the organization of work with visual display terminals of electronic computers, Resolution of the Ministry of Health of Ukraine No. 7 [Internet]. 1998 Dec 10 [cited 2025 May 01]. Available from: https://zakon.rada.gov.ua/rada/show/v0007282-98#Text
- State sanitary norms DSN 3.3.6.042-99. Sanitary norms of microclimate of industrial premises, Resolution of the Ministry of Health of Ukraine No. 42 [Internet]. 1999 Dec 01 [cited 2025 May 01]. Available from: https://zakon.rada.gov.ua/rada/show/va042282-99#Text
Full article (PDF), UKR