BHOPAL: A promising first-of-its-kind study of bioaerosols - air suspended particles of biological origin - in the Indo-Gangetic plains found surfeit bacteria and fungi in the air, many of which are disease causing harmful microbes resistant to multiple antibiotics.
It can be replicated across the country to develop an air quality bio index to generate alerts about possible outbreaks of diseases.
The ongoing study funded by the Indian Space Research Organization (ISRO) began around the outbreak of Covid-19 pandemic in 2019-end at the Department of Chemical Engineering and Technology, IIT-BHU Varanasi. It has been carried out at multiple sites in and around Varanasi like the sprawling Banaras Hindu University campus, municipal solid waste (MSW) processing site in Karsada village on Varanasi’s outskirts, waste water/sewage treatment plant in Ramnagar located across the Ganga and indoor sites like poultry farms and cowshed.
The study is being done by PhD scholar Yogesh Kumar Vishwakarma and two others under the supervision of Prof R S Singh.
Titled, “Study of Bioaerosols at Middle Indo-Gangetic Plain in Indoor and Outdoor Environments,” the research involves sampling the air at various sites for bioaerosols, and their quantitative and qualitative profile through whole genome sequencing/metagenome analysis. The study found way higher concentration of bacterial aerosols (around 81%) and lesser fungal aerosols (19-20%) in the PM10 and PM2.5 particulate matter in those sites. And the PM10 and PM2.5 levels were more than the recommended value of the National Air Quality Standards (NAAQS). Gram-negative bacteria, which are more pathogenic, had larger diversity, while the gram-positive bacteria were found more in numbers.
Among the fungi, mainly Aspergillus, Cladosporium, Penicillium and bacteria Bacillus, Acinetobactor and Enterobacter were dominant. Fungi like Talaromyces minioluteus, Periconia, Fusarium oxysporum, Cladosporium (which can cause several health issues) were also found among the bioaerosols.
The study also showed higher concentration of bioaerosols during summer and post-monsoon at nearly all the sites. Worryingly, most of the bioaerosols found in the finer size range can penetrate deep into the respiratory system and affect human health.
Most pathogenic bioaerosols were found at the dumping and traffic sites during the process of sampling, while the bioaerosols produced near waste water treatment plants (WWTP) were predominately in the size range of 2.1-4.7 μm. A fraction of fungal bioaerosols were also in ultra-fine range (0.65 μm). The strains of bacillus found near the WWTP showed resistance to higher concentration of antibiotic Cefixime and lower concentration of Azithromycin. Besides, at least two of the bacteria found near the MSW dumping site were resistant to higher concentrations of Cefixime and Azithromycin.
Among the three prime sites of study – agricultural site, traffic site (crowded roadside) and dumping site – gram-negative bacteria (which is more pathogenic) was found prevalent in air most near the dumping site, particularly during post-monsoon. However, during summers, they were found more near the roadside traffic site. The gram-positive bacteria were found more in the air near the traffic sites (crowded roadside), but comparatively lower at agricultural and dumping sites.
As for fungi, its maximum prevalence was detected near dumping sites during summer, but the prevalence at traffic sites was most during the post-monsoon season. The least prevalence of bacteria and fungi was reported near agricultural sites.
The study also found a nearly 50% rise in total culturable microbe concentration during foggy days as compared to non-foggy in urban habitat over the central Indo Gangetic Plains. Also, Bacillus, Enterobacter, coccus and fungi like Aspergillus, Cladosporium and Penicillium were found during the foggy days. Moreover, bacterial and fungal concentration during foggy days increased in coarse size fraction (4.7-7.0μm) compared to the fine (0.65-7.0μm).
The risk of exposure through inhalation and skin in children is much higher than in adults. It indicates that inhalation is the main cause of health risk from bioaerosol exposure, and children are at higher risk.
In all the indoor sites, the concentration of bacterial bioaerosols exceeded fungal ones (2 to 12 times), while such variation was exceptionally high in the poultry site (70 times). Acinetobacter and Bacillus sp. in bacteria and Penicillium, Aspergillus, and Cladosporium in fungi were most prevalent in indoor sites. Most bioaerosols found in these sites potentially cause severe health issues, including eye infections, pneumonia, respiratory diseases, gastrointestinal problems, and skin infections in healthy and immunocompromised bodies.
Prof R S Singh (Department of Chemical Engineering and Technology, IIT-BHU) said the study’s findings have already been published in international journals, including the Journal of Environmental Science and Pollution Research, Journal of Environmental Management Air Quality, Atmosphere & Health, and Journal of Environmental Science Advances.
“It’s a first of its kind study of bioaerosols in the central Indo Gangetic Plains. Using it as a model on a national scale through modern bio sensors can lead to the development of an air quality bio index, which can be correlated with human, animal and crop disease. By continuously monitoring the bioaerosol profile and numbers across the country, humans and farmers can be alerted well in advance about outbreak of diseases in various areas and regions,” Singh said.