Health risk assessment and characterization of PM2.5 bound bioaerosols at the municipal solid waste landfill site of Nagpur, India

Landfill being the reservoir of organic waste, serves as the most important source in the generation and emission of bioaerosols in the environment, and these bioaerosols have a significant impact on the environment and public health. In India, there are limited studies on the characterization of culturable bacteria and fungi in the bioaerosols originating from landfills. Therefore, the present study aimed to quantify and identify the bioaerosols and study their characteristics at a landfill site in Nagpur, India. The study describes the seasonal variation of PM2.5, PM2.5-associated bacteria and fungi in the landfill air, their molecular identification, antibiotic resistance, pathogenicity, dispersion and health risk assessment during winter and pre-monsoon seasons at the landfill site and surrounding residential sites in upwind and downwind directions. The study showed PM2.5 concentration was highest in the winter season (265.56 μg/m3) followed by the pre-monsoon season (173.1 μg/m3) at the landfill site. The culturable bioaerosol level was also significantly higher in winter (11056 CFU/m3) in comparison to pre-monsoon season (2244 CFU/m3) at the landfill site. Upon isolating and characterizing the microorganisms in the bioaerosols, some of the bacterial isolates, like Bacillus, Staphylococcus gallinarum, and Streptomyces speibonae were found to be resistant to chloramphenicol, netillin, nitrofurantoin, streptomycin etc. About 30% of the bacterial isolates were found to show β-hemolytic virulence activity. This indicated the presence of multi-drug resistant and potentially pathogenic bacteria in the bioaerosols over the landfill. The health risk assessment in adults indicated that the workers at the landfill site were at risk of bacterial aerosol in the winter season (hazard quotient i.e., HQ>1). The impact of bioaerosols on children needs to be investigated in the further studies and regular monitoring of bioaerosols is suggested to avoid any morbidity. To the best of our knowledge, this is the first study on the characterization of microorganisms from the bioaerosols over an open landfill site in India.