Spatial and temporal variation of bacterial population in ambient air particulate matters (PM2.5, PM10 and TSP) of Isfahan city, Iran

Introduction: Airborne particles are considered as an important indicator of outdoor air quality. Many health problems have been linked to high concentrations of Particulate Matters (PMs) and their associated microorganisms. The aim of this study, therefore, was to investigate the population of bacteria in PMs in various times and locations. Materials and methods: The PM samples including PM2.5, PM10 and Total Suspended Particles (TSP) were taken from 4 different stations of Isfahan city, Iran on February (cold season) and July (warm season), 2019 using an air sampling pump on culture media. The number of bacterial colonies was counted after 48 h growth in the incubator at 37 oC. The PMs concentration and some morphological characteristics of bacteria were also investigated. Results: The highest number of bacterial colonies was in TSP followed by PM10 and PM2.5. The bacterial populations at two stations in north and east. of the region in the warm season were higher than in the cold season, and the respective situation in the other two stations at south and center of the city was reversed, which seems somehow to have been the result of the PMs concentration of difference of pollution sources in various locations and seasons. Conclusion: This study highlights the importance of PMs pollution especially PM2.5 (i.e. the main factor affecting the air quality of the study area) as the carrier of microbial pollution in the air which could adversely affect human health.