• It isn’t just dust and noxious gases that are floating in the air. You also have bacteria, fungus and other microbes, which could contribute to the rise of allergens and respiratory infections in the city.
  • Since 2010, Bengaluru University has been monitoring bioaerosols in the form of bacterial contamination and fungal spores in the air. T
  • he annual average number of bioaerosol ranged between 64,000 Colony Forming Units per cubic metre to 89,000 CFU/m3.
  • While there are no standards for bioaerosols in the country, researchers say this exceeds the 10,000 CFU/m3 limit prescribed by the World Health Organisation (WHO) for indoor air quality.
  • The study, which also looked at seasonal variation, shows that the city is always under a barrage of bioaerosols, with bacterial microbes and fungal spores alternating in their peaks.
  • The pre-monsoon season, stretching from March to May, records the worst biological pollution quality, with CFU/m3 reaching upwards of 1,02,000.’
  • Warm temperatures in the city, coupled with urban heat island effect that can see certain areas record more than 37 degree Celsius, are believed to encourage bacterial growth.
  • Many bacterial organisms thrive in these warm temperatures, note researchers whose meteorological observation point to an increase in average temperature in the city from 24.1 to 24.4 degree Celsius in the past seven years.
  • During winters, when the air is slightly chiller, fungal spores dominate bioaerosols.
  • The lowering of humidity (to around 27%, compared to 50-60% in other seasons) ‘enhances’ spore formation.
  • Solid waste is a major contributor to bioaerosol pollution.
  • Rotting waste sees microbial release and is a platform for mould and fungal growth.
  • When released, they attach themselves to particulate matter pollution, which is on the rise through vehicles, construction and other pollution sources.
  • These minute particles are the ideal platform for bacteria to grow on.
  • The smaller the particle, the greater its reach in the lungs, and greater the health hazard.
  • Of concern is particulate matter which is less than 1 micron in size and can reach the smaller tracts within the lungs.
  • Currently, State agencies monitor particulate matter on two parameters: of 10 microns or less in size and of 2.5 microns or less.
  • The monsoon, which subdues much of the particulate matter, seeks lower bioaerosol counts in the city.

Tell us more about the Causes of Bioaerosol Pollution

  • From open dumpyards, landfills, waste strewn on streets, to frothing lakes and the burgeoning pigeon population, bacterial and fungal particles have multiple ways to get airborne.
  • While much of it can be natural — take for instance, fungus on trees shaken by the wind — rotting food waste in garbage dumps can aggravate matters
  • Even sewage flowing in the open spews out airborne toxins when it falls from a height.
  • What we need is for the civic body, water board and others to take bioaerosols into consideration in their policies to put an end to open dump yards, and the city is kept clean.
  • The health effects of bioaerosols have not been directly studied, leaving a gap in understanding their contribution to infections or allergies.
  • A recent study shows fungi causes 7.5% of allergies, which is the same as pollen. However, this is overshadowed by dust mites, which cause 60% of allergies.
  • In terms of bioaerosols, much needs to be studied.