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The influence of UV-LED lamps radiation on indicators of microflora in university auditoriums

ISSN 2223-6775 Ukrainian journal of occupational health Vol.19, No 1, 2023


https://doi.org/10.33573/ujoh2023.01.042

The influence of UV-LED lamps radiation on indicators of microflora in university auditoriums

Nazarenko V.I.1, Leonov Yu.I.1, Glyva V.A.2, Burdeina N.B.2, Cherednichenko I.M.1, Pochta V.N.3, Holubeva A.O.1
1SI "Kundiev Institute of Occupational Medicine of the National Academy of Medical Sciences of Ukraine", Kyiv
2Kyiv National University of Construction and Architecture, Kyiv
3LLC «LED Azimut», Kamianske, Dnipropetrovsk region


Full article (PDF): ENG

Introduction. There is a constant presence of a certain amount of bacteria, fungi and viruses in air and on surfaces of premises where a man spend a significant part of time today, that requires preventive measures. Recently, bactericidal ozone-free light-emitting diode (LED) sources of UV radiation have been introduced to disinfect the air in premises of various purposes, that requires researches of their effectiveness and hygienic regulation.

The aim of the study is to determine the effectiveness of the use of open-type bactericidal ultraviolet monochrome LED lamps for disinfection of work surfaces in auditoriums of a higher educational institution.

Research materials and methods. The studies of the bactericidal efficiency of open-type LED irradiators were carried out in three auditoriums of the Kiev National University of Civil Engineering and Architecture (KNUCEA) of the Ministry of Education and Science of Ukraine. LED UVC T5-5W-275NM lamps with a wavelength of 280 nm were installed in two auditoriums and their efficiency was assessed. Bactericidal air recirculators were additionally installed in one auditorium together with LED UVC T5-5W-275NM lamps and their mutual impact on the quantity of CFUs in this premise was evaluated. The duration of use of the bactericidal equipment was 3 months. The contamination of work tables in the auditoriums by an amount of colony-forming units (CFU) per 1 dm2 on surface area before and after exposure was studied. The swabbing method was used to determine the quantity of CFUs. The assessment of microbial contamination of indoor spaces was carried out in accordance with the recommendations of the SBM-2015 standard (Germany).

The results. The most contamination of the surfaces with mold fungi - up to 120 CFU/dm2 is observed in the points furthest from the entrance to the premises. The total microbial count in the center of individual classrooms reaches 194 CFU/dm2. Also, the microbiological studies indicated a small amount (1–7 CFU/dm2) of Staphylococcus aureus on table surfaces among 33–44% of the samples taken. There is a weak negative correlation between the number of CFU of mold fungi and the total microbial amount: before exposure, the Spearman correlation coefficient r=–0.314, after three months of UV exposure r=–0.463. There is a noticeble decrease in the quantity of CFU microorganisms on work surfaces (p<0.05) when using open-type UV-irradiators, while in a premises without such equipment the quantitative indicators of microflora practically did not change (p>0.05).

Conclusions. In university auditiriums on the surfaces of tables where students study, microbial contamination is detected from "light" (<20 CFU/dm2) to "extreme anomaly" (>100 CFU/dm2) degree according to the criteria of the SBM 2015 Guidelines for biological assessment of buildings (Germany ).

The use of LED UVC T5-5W-275NM bactericidal lamps of the open type in the presence of people leads to a decrease in microbial contamination of surfaces in all places of research by 2.8 times (p<0.05) or by 1-2 degrees, according to the criteria of the SBM 2015 Guidelines.

The simultaneous use of UV LED lamps and air recirculators allows to reduce the amount of colony-forming units (CFU) of mold fungi in the auditoriums by 20 times (р<0.05).

The introduction of modern energy-saving LED sources of bactericidal UV radiation is a promising direction for indoor air improvement. At the same time, there is a need to develop appropriate hygienic regulations for their use, taking into account the requirements of biological safety in accordance with the Order of the Ministry of Health of May 6, 2021 No. 882 and DSTU EN 62471:2017 "Safety of lamps and lamp systems photobiological (EN 62471:2008, IDT; IES 62471:2006, MOD)".

Keywords: indicators of microflora, bactericidal ultraviolet light-emitting lamps, disinfection of indoor surfaces.

References

  1. Dykyi IL, Kholupiak IYu, Shevelova NYu, Stehnii MYu, Filimonova NI. [Microbiology: textbook]. Kharkiv: Professional; 2006. 433 p. Ukrainian.
  2. Chuyeshov VI, Khokhlova LM, Lyapunova OO et al. [Normative acts on the organization of work of pharmacy and chemical-pharmaceutical enterprises. Technology of drugs of industrial production]. Pt 1. Kharkiv: Original, National Science and Technology Institute; 2013. 693 p. Ukrainian.
  3. Fierer N, Lauber CL, Zhou N, McDonald D, Costello EK, Knight R. Forensic identification using SK in bacterial communities. Proc Natl Acad Sci USA. 2010;107:6477-81. DOI: https://doi.org/10.1073/pnas.1000162107.
  4. Hübner N-O, Hübner C, Kramer A, Assadian O: Survival of bacterial pathogens on paper and bacterial retrieval from paper to hands: preliminary results. Am J Nurs. 2011;111:30-4. DOI: https://doi.org/10.1097/01.NAJ.0000408181.37017.82.
  5. Flores GE, Bates ST, Knights D, Lauber CL, Stombaugh J, Knight R, Fierer N. Microbial biogeography of public restroom surfaces. PLoSOne. 2011;6:e28132 DOI: https://doi.org/10.1371/journal.pone.0028132.
  6. Meadow JF, Altrichter AE, Kembel SW, Moriyama M, O'Connor TK, Womack AM, Brown GZ, Green JL, Bohannan BJM. Bacterial communities on classroom surfaces vary with human contact. Microbiome. 2014 Mar 7;2(1):7. DOI: https://doi.org/10.1186/2049-2618-2-7.
  7. [On the approval of sanitary and anti-epidemic rules and norms for the use of ultraviolet bactericidal radiation for air disinfection and disinfection of surfaces in the premises of health care institutions and institutions/institutions providing social services/social protection of the population, Order of the Ministry of Health of Ukraine No. 882 (May 6, 2021)] [[Internet] 2021 [cited 2023 Jan 20]. Available from: https://zakon.rada.gov.ua/laws/show/z0978-21#Text. Ukrainian.
  8. Public Health Center of the Ministry of Health of Ukraine. [Recommendations on the use of ultraviolet radiation (UV) for disinfection] [Internet]. 2020 Jun [cited 2023 Jan 20]. Available from: https://phc.org.ua/news/rekomendacii-schodo-vikoristannya-ultrafioletovogo-oprominennya-uf-dlya-dezinfekcii. Ukrainian.
  9. Lang D. The Spectrum of Mercury Low Pressure Lamps for Disinfection [Internet]. 2020 Apr 23 [cited 2023 Jan 20]. Available from: https://www.linkedin.com/pulse/spectrum-mercury-low-pressure-lamps-disinfection-dieter-lang.
  10. Mphaphlele M, Dharnadhikari AS, Jensen PA, Rudnick SN et al. Controlled trial of upper room ultraviolet air disinfection: A basis for new dosing guidelines. American Journal of Respiratory and Critical Care Medicine. 2015;192(4):477-84. DOI: https://doi.org/10.1164/rccm.201501-0060OC.
  11. Diffey BL. Solar ultraviolet radiation effects on biological systems. Physics in Medicine and Biology. 1991;36 (3):299-328. DOI: https://doi.org/10.1088/0031-9155/36/3/001.
  12. Nazarenko VI, Cherednichenko IM, Leonov YuI, Pochta VN, Shevchenko AV, Burdeina NB, Yarygin AV. The hygienic principles of using bactericial 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.
  13. Ultraviolet air and surface treatment. Ch 62. In 2019 ASHRAE Handbook-HVAC Applications [Internet]. 2019 [cited 2023 Jan 20]. p. 62.1-62.17. Available from: https://www.ashrae.org/file%20library/technical%20resources/covid-19/i-p_a19_ch62_uvairandsurfacetreatment.pdf.
  14. Leonov YuI, Nazarenko VI., Myshchenko I. Microbiome of office premises and prevention of its harmful effect on office workers (review article) Ukrainian Journal of Occupational Health. 2022;18(1):63-70. DOI: https://doi.org/10.33573/ujoh2022.01.063.
  15. Supplement to the Standard of Building Biology Testing Methods SBM-2015: Building Biology Evaluation Guidelines for Sleeping Areas. Baubiologie maes. Inst. für Baubiologie und Nachhaltigkeit; 2015. 4 p.
  16. Makhniuk VM, Harkavyi SI, Nazarenko VI, Chorna VV. Research of the factors influencing the health of rural and urban schoolchildren studying at secondary educational institutions by sanitary-hygienic indicators. Environment and Health. 2020;94(1):56-63. Available from: https://dspace.vnmu.edu.ua/123456789/5739.
  17. Katiyar V. Assessment of indoor air micro-flora in selected schools. Adv Environ Res. 2013;2(1):61-80.DOI: https://doi.org/10.12989/aer.2013.2.1.061.
  18. Redchits MA, Serheta IV, Redchits YeM. [Ultraviolet bactericidal irradiation of the air of classrooms for junior lyceum-students and its efficiency]. Reports of Vinnytsia National Medical University. 2019;23(2):304 -8. DOI: https://doi.org/10.31393/reports-vnmedical-2019-23(2)-23 Ukrainian.
  19. Surmasheva OV, Chernysh OO, Borovyk MP. [Evaluation of the effectiveness of indoor air disinfection using an ultraviolet bactericidal recirculator]. In Ecology and Medicine: proceeding of international scientific and practical conferences. Kyiv; 2021. p. 285-289. Ukrainian.
  20. State Standard of Ukraine EN 62471:2017. [Safety of photobiological lamps and lamp systems (EN 62471:2008, IDT; IES 62471:2006, MOD)]. Kyiv: UkrNDNC; 2018. 33 p. Ukrainian.
  21. Directive 2006/25/ec of the European Parliament and of the Council 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. 2006 Apr 27;49:L114/38-L114/59. Available from: https://eurlex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2006:114:0038:0059:en:PDF
  22. ISO 15714:2019(en). Method of evaluating the UV dose to airborne microorganisms transiting in-duct ultraviolet germicidal irradiation devices [Internet]. 2019 [cited 2023 Feb 20]. Available from: https://www.iso.org/obp/ui/#iso:std:iso:15714:ed-1:v1:en.
  23. Kovalenko NO, Zamazii TM, editors. [Sanitary microbiology: methodological guidelines for the discipline "Microbiology, virology and immunology" for master's students of the II-III courses in the specialty "Medicine", "Dentistry" of the educational qualification level - "Master"]. Kharkiv: KhNMU; 2021. 48 p. Ukrainian.
  24. Shirobokov VP, editor. [Medical Microbiology, Virology and Immunology: textbook for students of higher medical education institutions]. 3rd ed., updated and added. Vinnytsia: Nova Kniha; 2021. 920 p. ISBN 978-966-382-874-9 Ukrainian.