Thanks to high levels of nitrogen oxides (NOx) and respirable suspended particulate matter (RSPM), the air quality level in the city since the start of the month has been poor compared to the same period last year.
The NOx and RSPM have breached the permissible limits, according to the data recorded at the air quality monitoring stations at Bandra and Sion set up by the state pollution control board.
NOx levels at Bandra for the month have been beyond 100 microgrammes per cubic metre (µg/m3), much above the safety limit of 80µg/m3.
The levels were the highest two days before Diwali -- 164µg/m3 on November 9 and 155µg/m3 on November 4.
The RSPM levels at Bandra, however, were above the permissible limit throughout the month last year.
“NOx is known as the silent killer. It is colourless, odourless and tasteless, and yet causes major respiratory and health effects,” said Philip Earis, scientist and resident of Bandra. “The problem is acute for people living, working or travelling on or near busy roads or junctions.”
While the NOx levels at Sion were closer to the permissible limit this month, the same was not the case with the RSPM levels.
Barring two days (November 4 and November 5), these fine particles have been above the permissible limit throughout the month.
The highest RSPM level at Sion was recorded on November 15 (237ug/m3), against the safety limit of 100ug/m3. At Bandra, the RSPM levels reached its peak at 186ug/m3 on Diwali day (November 11) and continue to stay high.
In November 2014, the RSPM and NOx levels were below permissible limits for most of the month at Sion, with the monthly average reading of 99-105ug/m3.
“The rise in pollution levels could be attributed to fuel combustion from diesel vehicles that account for 90% of the load on the road,” said Rakesh Kumar, chief scientist, National Environmental Engineering and Research Institute. “More private vehicles cause traffic congestion, releasing toxic fumes that deteriorate the city’s air quality.”
Experts said proper traffic management could help control the release of pollutants. “The ground staff controlling the traffic needs to plug all loopholes by taking note of malpractices when it comes to vehicular emissions and initiate compulsory environmental charge for trucks entering the city,” said Vivek Chattopadhyay, clean air programme manager, Centre for Science and Environment, Delhi, adding,
“Using public transport, car-pooling and shifting from diesel vehicles to petrol are short-term measures.”