BIOAEROSOLS AND AIR QUALITY IN QATAR: EXPOSURE, BIODIVERSITY AND EFFECTS ON HUMAN HEALTH

Abstract

Although research on bioaerosols dates back many years, it has received increased attention recently, with a focus on both culture-based and cultureindependent methods for sampling and analysis. Studies have identified seasonal variations in microbial communities and their links to specific environmental atmospheric conditions. Understanding airborne microbial populations is crucial for both public health and atmospheric science. In earth’s lower atmosphere (the troposphere), airborne microbiome has a vital role for both human health and environmental dynamics which makes them a potential area of bioaerosol research. This study set out to explore diversity, structure and distribution of bioaerosols over time and space in the ambient air of Qatar. In the ambient air of different suburban locations in Doha, this study also analyzes the particle size distribution along with antibiotic resistance (ABR) of airborne bioaerosols. For spatial and seasonal fluctuations, Coriolis® μ sampler was used to collect air samples over a span of one year from ten different locations spread across Qatar. These locations were selected because of their unique geographic conditions, use and functionality. The results found that spatial and seasonal variation had a strong influence on bioaerosol concentrations. During the sampling campaign, bacterial concentration resulted higher during dry-hot summer (averaging 514±77 CFU/m³) while fungal concentration peaked during winter (averaging 134±31 CFU/m³). Elevated bacterial concentration was reported at 80% of the sites during dry-hot summer and fungal concentration at 70% of the selected sites during winter. For microbial size distribution, samples were collected diurnally both with viable cascade six stage Andersen sampler and a liquid impinger (Coriolis® μ) from October 2021 up to January 2022. Results reported that mean fungal concentration remained lower than that of bacterial concentration. The microbial concertation values reported for bacteria and fungi are 464 CFU/m3 and 242 CFU/m3 respectively. Both fugal and bacterial concentration found at its peak in morning samplings as compared to the afternoon. Moreover, highest concentration of bacterial and fungal concentration is recorded in the aerodynamic particle size range of 1.10–2.21 μm. Abundance of bacteria were found to be higher during the winter season compared to the warmer autumn season. During the size distribution study with Andersen sampler, 24 culturable bacterial species were found. Highly abundant bacterial species includes Pasteurella pneumotropica (9.71%), Pantoea spp. 1 (8.73%), and Proteus penneri (7.77%) spp. During winter and autumn months, phylum level bacterial community configuration was almost same as identified by the molecular genomics. The predominant in the phylum level identification was the Proteobacteria followed by Bacteroidetes, Firmicutes, Planctomycetota and Acidobacteriota,. However, notable differences in the dominant genera were observed during low temperature months of autumn as well as winter. The most prevalent genera identified were Paraburkholderia, Sphingomonas, Comamonas, Bacillus, and Lysinibacillus. Additionally, the highest levels of antibiotic resistance (ABR) were recorded during December, with bacterial bioaerosols showing resistance to at least 5 out of 10 tested antibiotics, where as complete (100%) resistance to Metronidazole across all samples. Microbial diversity from lab studies after outdoor sampling during different spatiotemporal conditions revealed the presence of different clinically important bacteria and fungi. These included bacteria identified like Chryseobacterium, Pseudomonas, Pantoea, Proteus, Myroides, Yersinia, Pasteurella, Ochrobactrum, and Vibrio, as well as fungal genera such as Aspergillus, Rhizopus, Fusarium, and Penicillium. Identification of culturable microorganisms was conducted through comprehensive biochemical testing and microscopic examination. In humid-hot summer season, the highest antibiotic resistance (ABR) was reported during this study. ABR results revealed strong bacterial resistance to Metronidazol, a commonly used antibiotic. Based on these results, health risk assessments indicated that exposure to high concentrations of certain airborne microorganisms (bioaerosols) could pose a risk to human health. Bacterial species identified in this study are known to cause respiratory infections and can have adverse effects on both public health and the environment. By application of metagenomic analysis, a diverse array of airborne bacterial taxa was identified which was not possible to be identified by culture-based techniques in the lab. This study provides detailed information about spatiotemporal bioaerosol concentration, their diversity and ABR in the outdoor/ambient air of Qatar. The findings contribute to air quality evaluation frameworks and serve as a foundation for public health policy development, particularly relevant to arid climatic zones.