Vehicles, high-rises are poisoning the Mumbai air

It’s time to apply the brakes. The city’s love for cars and high-rises is taking a heavy toll on the quality of its air.

According to latest studies carried out by the Maharashtra Pollution Control Board (MPCB), air pollution levels in the city are approaching the point of no return.

The MPCB had conducted two studies — one to plot the annual concentration of pollutants, and the other to track the month-wise pollution rate — to map the air pollution trend.

The first one revealed an alarming rise in the annual concentration of pollutants like sulphur dioxide (SO2), nitrogen oxides (NOx), and respirable suspended particulate matter (RSPM) in the last four years. The rise was 36%, 13%, and 11%, respectively.

Further, the concentration of these pollutants in the air was way above the prescribed limits, the study found. The NOx levels, for instance, have reached a level (86 micrograms per cubic metre of air — µg/m3), which is more than twice the prescribed limit (40µg/m3). Annual concentration of RSPM levels (202µg/m3), too, was found to be twice the permissible limit, whereas SO2 levels were below the set limit of 50µg /m3. MPCB officials said that a 36% jump in four years in the pollutants’ level was disturbing.
The study, which mapped the month-wise trend over a period of 19 years, suggested a similar trend.    

“Daily emissions of RSPM and Nox have risen alarmingly across the city since 2005. The daily rate of emission of SO2 has risen at several places too,” the study found. The MPCB used data collected from monitoring stations at Kalbadevi, Parel and Worli to map the daily emission trend from 1990 to 2009.

Mahesh Phatak, the board’s member secretary, said that an increase in S02 and RSPM level could be attributed to an increase in vehicular activity in the city. He added that construction activity also contributed to rise in RSPM, besides causing a jump in Nox levels.

To reduce vehicular emissions, the state enforced Euro-III standards in 2005. While this has reduced the per capita emission, Phatak said that its overall impact on the air quality has been neutralised by rapid rise in the number of vehicles.

“About 250-300 new vehicles are being registered daily,” he said. Phatak added that the only way to reverse the negative trend was to exercise “restraint” on the use of private vehicles.

A senior MPCB scientist said that while restricting construction
activity was not advisable as it concerned the city’s development, authorities, including the pollution board itself, must ensure that these are carried out in a way that causes least harm to the environment.

The pollution board has set norms for “hygienic” construction activity. The scientist, however, said these are often ignored. Ironically, the monthly data indicated a decrease in levels of other pollutants like ammonia and hydrogen sulphide, among others.

Phatak indicated that this was owing to a decline in industrial activity in Mumbai. The MPCB has collated month-wise data from 1990-2009.