The numbers may have improved slightly in the city, but Bengaluru remains far from achieving healthy air levels.
All the monitoring stations continue to record higher than permissible limits of air pollution (the national limit is 60 micrograms per cubic metre) and a long way away from the international standard of 25 micrograms per cubic metre prescribed by World Health Organisation.
“The reduction is good, but clearly not good enough. The levels continue to remain high, and will be felt worse at nose-level than the ambient (often, 10-15m above ground level) pollution as recorded by the Karnataka State Pollution Control Board (KSPCB),” said Nandi Sivalingam, campaigner with the NGO Greenpeace.
A 2015 study by Centre for Science and Environment showed that the street-level exposure was between three and 12 times more than what is measured by pollution control boards. The reduction in numbers could be attributed to local factors: for instance, construction of Namma Metro Phase I or grade separators threw up significant amount of dust in local areas.
“Instead of manual measurement of pollution a few times a week, a real-time continuous monitoring is needed to actually understand air pollution levels in the city,” said Mr. Sivalingam.
A TERI source appropriation study in 2010 showed that the road dust and construction contributed up to 50.6%, while transportation was responsible for 19% of all PM10 pollution.
Considering data over the past few years, air pollution peaked in 2014-15 when PM10 had touched 283% above the standard limits of 60 micrograms per cubic metre. Now, in the whole of 2016-17, the maximum recorded was at Central Silk Board junction at 120% above standard limits.
Lakshman, KSPCB Chairman, said the reductions were owing to “better traffic management”. “Compared to a few years ago, potholes are being filled. Moreover, on our insistence, there is an effort to pick up road dust from the streets,” he said.
As cars increase, so does nitrous oxides
With nearly seven lakh vehicles being added annually to the city, the levels of nitrous oxides is on the rise.
A comparison of the air pollution data between 2014 and 2017 shows that at all monitoring stations operated by KSPCB, the nitrous oxide levels are steadily increasing with the city railway station area seeing a staggering increase of 99% in pollutants since 2013.
A TERI source appropriation study showed that the vehicles on the road contribute more than 68% of the nitrous oxides levels in the city. Considering that nearly 20 lakh vehicles were added to the city’s road between March 2014 and July 2017, the increase in NOx levels is not surprising.
“Our mobile emission vehicles have tested over 15,000 vehicles, of which 13% of petrol and 28% of diesel vehicles exceed norms. Among the violators, we are analysing the type of vehicle as well as year of manufacture. With this, we will know what kind of vehicles need to be the target to bring out vehicular pollution,” said Lakshman, KSPCB Chairman.
Curiously, KSPCB officials note that pollution levels have spiked near Metro stations as more autorickshaws, cabs and vehicles throng there as part of the last-mile connectivity.
