In what could put the city at a risk of respiratory problems, levels of nitrogen dioxide (NO2) were beyond permissible limits in the air in 2018-19, according to the Brihanmumbai Municipal Corporation’s (BMC) annual environmental report. The level of ammonia (NH3) was below the permissible levels, except for Deonar, where it was dangerously high. The concentration of sulphur dioxide (SO2), however, remained below the permissible levels. In most areas, however, the levels of the gases were lower than the previous year.
The report looked at the concentration of the three gases at five different spots – Worli in south central Mumbai, Khar and Andheri in the western suburbs, Bhandup and Deonar in the north-eastern suburbs of the city – through the year. Deonar was not included in the survey before 2018-19.
At 69 micrograms per cubic meter, Andheri saw the maximum concentration of NO2, which is mainly caused due to burning of fossil fuel from motor vehicles and industries. Last year, the concentration in the area was 73 micrograms per cubic meter. The permissible limit of NO2 is 40. The NO2 level was 50 micrograms per cubic meter at Worli, 55 micrograms per cubic meter at Bhandup and 59 micrograms per cubic meter at Deonar.
Anumita Roy Chowdhury, executive director (research and advocacy), Centre for Science and Environment, a non-profit public interest research and advocacy organization, said, “Enhancing public transport network and reducing use of private vehicles will help reduce the concentration of NO2.”
In Deonar, ammonia level was 128 micrograms per cubic meter, higher than the permissible limit of 120 micrograms per cubic meter. Ammonia is generated mainly due to improper waste management in urban areas. “People with existing lung diseases can get breathless, with aggravated symptoms, especially those residing close to the dumping ground,” said Dr Sanjeev Mehta, pulmonologist, Lilavati Hospital in Bandra. “High ammonia concentration is an indication of mixed waste burning at landfills, which can be toxic for residents living in close proximity of the dumping ground,” said Roy Chowdhury.
The ammonia levels in Deonar had risen after the 2015 fire, which was on for days. The SO2 level at Deonar too was the highest among all spots.
Experts said waste management, segregation, composting and recycling is needed to keep a check on dangerous gases.
Vijay Singhal, additional municipal commissioner who heads the environment department, said, “The BMC is taking steps towards a healthier environment – be it implementing the parking policy to discourage private use of vehicles or processing more waste at the dumping grounds. Earlier, we processed 3000 tonnes of garbage daily at Kanjurmarg dumping ground which is up to 5500 tonnes now.”