Delhi breathed easier from January to April

NEW DELHI: Good weather and steps to control air pollution helped Delhi breathe easier through the January April period this year. Central Pollution Control Board (CPCB) data for all four months shows the average levels of PM 2.5 (tiny breathable particles) and the air quality index (AQI) values at most places in Delhi improved over 2016.
This does not mean Delhi's air was `clean' but only `less dirty'. For instance, in January , the average PM2.5 concentration at Anand Vihar fell from 428 micrograms per cubic metre (gm3) last year to 322 gm3, which is more than five times the acceptable limit of 60 gm3. At Dilshad Garden, the level reduced from 396 gm3 to 249 gm3. Average pollution le vels were 1.6 to 5.4 times higher than the limit at all the monitored locations--Anand Vihar, IHBAS-Dilshad Garden, Mandir Marg, NSIT Dwarka, Paschim Vihar, RK Puram and Shadipur.

Weather played a major role in reducing pollution during the cold months this year, said Ravinder Vishan, head of Regional Weather Forecasting Centre at India Meteorological Department (IMD). “In January and February, we had northwesterly winds instead of calm condi tions or easterlies.

In March and April, pollutants are dispersed easily anyway .“ Steps taken to stop polluting activities last winter might have also helped. For instance, the coal-burning Badarpur power plant was shut for more than four months after severe smog in November 2016 when the PM2.5 level hit 700 micrograms per cubic metre--12 times the acceptable limit.

Although PM 2.5 concentrations in May were higher than the 2016 levels at Shadipur, RK Puram, Mandir Marg and Anand Vihar, the air could have been dirtier but for reduced crop stubble burning in Punjab and Haryana, satellite images showed.

Reduction in truck traffic after Supreme Court imposed an environment compensation charge (ECC) in October 2015 might also be a longterm factor for clean air.

The SC had doubled the ECC amount in December the same year, and South Delhi Municipal Corporation--which is in charge of toll tax collection in Delhi--now earns about Rs 1crore daily as ECC. An official told TOI that truck traffic had reduced by about 30% after the ECC was imposed. The results show strict implementation of rules can clean up the air, said environmentalist Anumita Roy Chowdhury , executive director at Centre for Science and Environment (CSE).

“There is much more vigilance this year because of a committee set up by the lieutenant governor and strong orders from the Supreme Court.“

The gradual phasing out of Bharat Stage-III and older vehicles after BS-IV norms were made mandatory in April will also improve air quality in the long run. “There will be a reduction of nearly 80% in emissions from trucks because of BS IV ,“ Roy Chowdhury said.

Sagnik Dey, associate pro fessor at IIT Delhi (Centre for Atmospheric Sciences), said “rigorous scientific analysis“ of the data will show what really brought down air pollution this year--the weather, government action and policies, or both. “If the actions taken recently are contributing to the decrease, next year should also show the same trend.“ He also advised studying data from Ghaziabad, Noida, Faridabad and Gurgaon where similar environmental measures were not enforced.