Small pollutants in Mumbai’s air 5 times more than WHO limit: Study

The concentration of fine particulate matter (PM2.5) in Mumbai was over five times the World Health Organization (WHO) standards in 2018.

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Mumbai recorded an annual average of 51.8 micrograms per cubic metre (μg/m3) against the international safe limit of 10μg/m3, while the safe limit for India set by the Central Pollution Control Board (CPCB) is 40μg/m3, according to a pollutant concentration and emission inventory study.

Delhi-based air pollution research group UrbanEmissions.info, under its air pollution knowledge assessment (APnA) city programme, facilitated by non-profit Shakti Sustainable Energy Foundation, released its data for 30 cities, including Mumbai, on Thursday.

“We found that the PM2.5 pollution in urban Mumbai varies between 27 and 76.6μg/m3, with an overall average of 51.8μg/m3, which is five times more than WHO guidelines,” said Sarath Guttikunda, lead author, founder and director, Urbanemissions.info.

CPCB officials said pollution concentration should be compared only with national standards. “Every country has their own scientifically designed standards because they have been framed in wider consultation with experts from various fields, keeping in mind background ambient base level concentrations, without any human-induced emissions, which would be different for India than any other country,” said V Shukla, in-charge of air quality management, CPCB. “However, India periodically reviews its standards, and very soon it will be evaluated again based on changing concentration and emission sources.”

PM 2.5 are pollutants of the smaller kind, with a diameter not more than 2.5 micrometers. They are “fine particles” which can stay in the air for days or weeks and are small enough to invade even the narrowest of airways leading into the body causing health ailments. Mumbai has 19 air quality manual monitoring stations, 11 continuous monitoring (real-time) stations, but the study indicated that 68 stations were required to map detailed pollutant concentrations.

The study found that PM2.5 levels were highest over the past four years against concentration recorded every year over the past two decades. Urbanemissions.info assessed PM2.5 concentration between 1998 and 2016 using satellite observations and global model simulations. PM2.5 levels had peaked in 2015 to 55.9μg/m3 (highest in 20 years), which fell to 49.1μg/m3 in 2016 and increased again to 51.8μg/m3 in 2018. “There has been a gradual rise in pollution levels because of a steady increase in all sources for PM2.5 concentration, including population, quantum of waste generation, use of energy, use of transport, and construction demand, and very little on the actions to control these levels over the years,” said Guttikunda.

Shukla said Mumbai’s air pollution action plan had been approved in June and implementation was underway. “The first status report of the action plan needs to be submitted by September and thereafter every four months until 25% reduction in air pollution sources is achieved,” he said. The Maharashtra Pollution Control Board (MPCB) said they needed to study the report.