Air quality in Delhi and surrounding regions continued to be in the ‘severe’ category on Friday with monitoring stations reporting average particulate matter (PM2.5 and 10) levels of 450 micrograms per cubic metre (ug/m3). The safe limit of PM2.5 is 60 ug/m3, while the standard for PM10 is 100 ug/m3.
The Capital recorded an Air Quality Index of 458 (severe) on Friday. The air quality has been in this zone since Tuesday.
Pollution monitoring and forecasting agency SAFAR attributed the pollution to secondary particulate formation due to drizzle across the city. Such rain is particularly detrimental to air quality as it makes particulate matter ‘ stickier’ and harder to be flushed out by the wind.
However, authorities said that wind speed is likely to pick up by Sunday. “An increase in wind speed is forecast for the next three days, which may increase ventilation and improve air quality marginally,” said SAFAR’s Friday report. Stubble burning, a major contributor to the city’s pollution level during this season, may cease to be a key cause in the coming days as the winds that bear pollutants are likely to shift away from Delhi.
The contribution of stubble burning has come down to 5%, said SAFAR; from a high of 25% on November 12.
The Supreme Court on Friday expressed concern that reduction in stubble burning had not reduced pollution in Delhi.
The Centre said that it was examining the feasibility of putting up ‘smog towers’ to reduce pollution in the city. The towers are expected to suck in surrounding air, pass it through a system of filters, and eject clean air. Earlier this week, Union Environment Secretary C.K. Mishra had said that miniature versions of smog towers, called WAYU filters, that were being tested since last year had not worked.
