Bioaerosols, less-talked-about pollutant one ought to watch out for

Air-conditioned vehicles where the AC filters are not changed for long aid to the growth of bacteria and fungus. Credit:Tejas Dayananda Sagar

Exposure to bioaerosols could lead to infectious diseases like asthma, allergic rhinitis and cancer. Credit:Tejas Dayananda Sagar

Garbage dumping in the city. Credit:Tejas Dayananda Sagar

By Kapil Kajal
While vehicular and industrial emissions, construction dust and garbage burning are the main culprits behind the air pollution in Bengaluru, open sewage, solid waste dumping, landfills and frothing lakes have also caused a rise in air pollution.

According to a study by the Department of Environmental Science (DES) of Bangalore University (BU), there has been a rise in the increase of bacterial aerosols or bioaerosols, emitted from open dumps, since 2010. Bioaerosols are airborne particles or large molecules carrying living organisms or released from living organisms (bacteria, fungi, viruses and pollen) and they originate from almost any environmental reservoir for microorganisms, such as fresh and marine surface waters, soil, plants, bioreactors, wastes, animals and human which can contribute as much as 25% to the atmospheric aerosols, defined the study.

The particles in a bioaerosol are generally 0.3 to 100 µm (1 m = 10 lakh µm) in diametre, but the respirable size fraction of 1 to 10 µm is of primary concern as the smaller particles will be inhaled while the larger ones deposited on surfaces, said a study by the Indian Journal of Medical Microbiology (IJMM).

Dr Yellapa Reddy, the Governing Council Member of the Foundation for Ecological Security of India, attributed the foul smell of garbage to bioaerosols. He highlighted that the piles of garbage around the city lead to increase in bioaerosols, which are harmful to health.

He castigated the administration and the citizens for being in denial about the extent of pollution caused by bioaerosols.

The permissible limit of bacteria and fungi (BBF) in the air is 10,000 colony forming units per cubic metre (CFU/m3). According to the BU study, by the BBF levels in 2010 was 58,827 CFU/m3, while it had risen to 83,256 CFU/m3 in 2017.

The study listed improper waste collection at the household level, lack of perception on solid waste management, lack of coordination of localities and Bengaluru city municipal authority, dumping of solid waste are reasons behind the dispersion of bioaerosol.

A report by BU found out that the level of microorganisms like E. coli and Fecal streptococci in water samples collected from the city’s Byramangala reservoir was above the limit prescribed by WHO and wasn’t suitable for agricultural purposes.

Nandini N, the chairperson and professor with DES, BU, stated that the concern is that if the air has a dust particle size less than 2.5µm, it will be present in breathable air and this is the problem we are facing in urban cities like Bengaluru. This air is attached to the bacterial and fungal organism and that air we breathe in and it reaches our lungs, which causes infections and respiratory problems, she added.

Indoor bioaerosols

The bioaerosols are also present inside our homes. The presence of undesirable bioaerosols is often associated with sick building syndrome and building-related illnesses. Sources include furnishings and building materials; fungal contamination within walls, ceiling, and floor cavities by the movement of cells, spores, and cell fragments via wall openings and gaps at structural joints while lack of fresh air due to increased insulation of buildings, poorly maintained or operated ventilation systems, poorly regulated temperature and relative humidity levels also contribute to the presence and multiplication of bio-aerosols, added the IJMM study.

Nandini added that air-conditioned rooms where the AC filters are not changed for long aid to the growth of bacterias and fungus. It is also prevalent in AC buses and theatres, she mentioned.

Health impact

Exposure to bioaerosols could lead to infectious diseases which arise from viruses, bacteria, fungi, protozoa and helminths, respiratory diseases including asthma, allergic rhinitis and cancer. Inhalation of bacterial aerosol or bioaerosols can cause hypersensitivity in the lungs, urinary tract infection, bacteremia, bacterial endocarditis, diverticulitis, and meningitis, the BU study said.

There are control measures including proper elimination of the microorganisms from the houses, offices or indoors, use of high-efficiency air purifiers, proper ventilation and using disinfectants, which can control bioaerosols from the indoor space said Dr Shashidhara Gangaiah, a paediatrician with the Center for Science Spirituality in Bengaluru.

Outdoor bioaerosols cannot be controlled without cleaning the environment, lakes and proper solid waste management, added Nandini.

(Author is Bengaluru - based freelance writer and a member of 101Reporters.com, a pan-India network of grassroots reporters.)