Effect of coronavirus (Covid-19) pandemic on biological air pollutants: a case study of Valiasr hospital in Zanjan (2019-2020)

Background and Objective: Bioaerosols as small particles enter the body by inhalation and lead to respiratory diseases based on type, concentration, and exposure time. In sensitive workplaces such as medical centers, it is necessary to pay attention to the type and population of these pollutants and the possibility of nosocomial infections. In the present study, the population and type of bioaerosols (bacteria and fungi) in the air of different hospital wards under normal conditions, visiting hours, and Covid-19 pandemic was evaluated. Materials and Methods: Air sampling was carried out in different wards and ambient air of Valiasr Hospital of Zanjan during September 2019 (morning and visiting hours) and October 2020 (Corona pandemic) using an air sampling pump (Flite 3- SKC Ltd) with a flow of 14.1 L/min and then cultured in Sabaroud dextrose agar and nutrient agar. Results: The results showed that air pollution in wards such as infectious diseases and clinics in both periods was more than other wards. The microbial density during visiting hours (before the coronavirus outbreak) was almost 30% higher than normal conditions. In October 2020, due to the coronavirus outbreak and reduced traffic, microbial air pollution in the hospital decreased. In both periods of study, the frequency of gram-positive bacteria, especially Staphylococcus species (49%) was higher than other bacteria and among fungal species the frequency of Aspergillus (47%) was higher than others. Conclusion: This study showed that traffic restrictions caused by the coronavirus pandemic reduce microbial density in hospital space and this achievement can be used in the future with the aim of improving air quality and controlling nosocomial infections.