NEW DELHI: Delhiites are likely to breathe in severely polluted air the day after Diwali. At present, the capital's air quality is hovering in the category range of 'moderate' and 'very poor' according to the national air quality index launched by the Centre on Friday.
But a forecast made by System of Air Quality and Weather Forecasting and Research (SAFAR) under Indian Institute of Tropical Meteorology, factoring in weather and estimated quantity of crackers burnt warns of extremely poor air quality in Delhi starting Diwali.
Winter has not set in yet, the average temperature being slightly higher than what it had been this time last year and one year prior. But air pollution is likely to reach dangerous levels despite the warm weather. The analysis suggests that in case there is a 22% reduction in the amount of crackers burnt from last year the pollution levels will still make it to the 'very poor' category in areas that would otherwise be graded 'severe'. "There will be a rapid increase in fine, respirable particles (PM2.5) from October 22 but the rate of increase in coarse particulate matter (PM10) will be slower," SAFAR says.
The temperature in many parts of Delhi is likely to come down. This, however, is not only due to the change in weather pattern. Increase in aerosols over Delhi is likely to thicken the boundary layer or the lowest part of the atmosphere usually till 1-2km above the earth's surface. "In NCR, there will be rapid loading of aerosols during Diwali. It's likely to enhance aerosol optical depth by 35%," says a statement by SAFAR on Tuesday.
AOD is the degree to which aerosols (airborne solid and liquid particles) prevent transmission of light in an area-and it's also considered a proxy for air quality. Enhanced AOD is likely to deplete this boundary layer to as little as 150 metres on October 24 morning. Fortunately, the boundary layer will remain much higher than the 50-70 metres it hit last year.
The highest pollution levels are likely to be recorded at Mathura Road followed by DU, Pusa or New Rajendra Nagar and Noida. Pollution levels are likely to be relatively lower in Palam (T3) and Aya Nagar. The level of oxides of nitrogen oxides (NOx) is likely to shoot up. The current NOx levels in Delhi are between 20 and 35 parts per billion. This is likely to shoot up to 30-65ppb.
