Already faced with high levels of suspended particulate matter (SPM), citizens have a new reason for worry: the BMC’s annual Environment Status Report (ESR) has shown higher-than-permissible levels of nitrogen dioxide (NO2). The high levels of NO2 is largely due to vehicular emissions, and exposure to large quantities can lead to respiratory ailments, including asthma.
According to the ESR for 2017-18, the city’s levels of NO2, PM2.5 and PM10 are much higher than the Maharashtra Pollution Control Board’s prescribed norms. Levels of sodium dioxide and ammonia have also increased, but are still within permissible limits. The annual average PM2.5 levels for Mumbai stands at 54, when it should be 40; similarly, the annual average for PM10 levels stand at 93 when it should be 60. Particulate matter levels have been high for the third year in a row.
Every year, BMC brings out a comprehensive ESR that looks into various indices of the city’s environment and development. Broadly, the topics include air and noise pollution, water contamination, health, power supply, roads and traffic, solid waste, sewage disposal etc.
BMC has six monitoring systems at various locations for ambient air quality, where air quality is tested manually using high volume samplers. All recorded above-limit levels for NO2 ranging between 62 and 76, while the permissible limit is 40. Above-limit levels were recorded for the third consecutive year, with even the 24-hour average for NO2 levels crossing the 80 mg/cubic metre benchmark (standards are different for daily and annual).
Concerned, say experts
Dr. Rakesh Kumar of the National Environmental Engineering Research Institute, said, “NO2 levels are definitely a matter of concern. They affect the inner lining of the throat, due to which, in most cities, people complain of sore throat in the morning. Some forms of particulate matter can cause cancer.”
Dr. Gufran Beig, director, SAFAR, said, “Particulate matter levels have long exceeded permissible limits. They are a great cause of concern as they directly penetrate the lungs. NO2 levels are not alarming right now, but need to be watched. On 5% of the days last year, Mumbai’s air quality was very poor, and on 16% of the days, it was poor.”
If it is any solace, levels of SO2 and ammonia were under control; ammonia was in the 60-85 mg/cubic metre range (permissible level: 100), while SO2 measured in the 12-20 mg/cubic metre range (permissible level: 50). Annual average levels of ozone are showing a decreasing trend, while there hasn’t been a noticeable change in carbon monoxide levels.
