The air pollution level in the days before and after Diwali will be lower than the previous four years in Delhi, if the firecracker ban is strictly followed, according to a forecast from the Centre’s System of Air Quality and Weather Forecasting and Research (SAFAR).
In the previous years, the concentration of PM 2.5 – fine, inhalable particles suspended in the air – has reached close to 700 micrograms per cubic metre air (µg/m3) – 11 times higher than the exposure limit of 60 µg/m3.
However, this year, the Delhi government has imposed a ban on the sale and use of all types of firecrackers, including the “green” variants.
The SAFAR forecast said, “The overall air quality of Delhi was in the very poor category on Thursday. It is forecast to deteriorate and remain in the higher end of very poor levels in the absence of any additional emissions due to fireworks during the Diwali period… Under zero firecrackers scenario, the level of PM2.5 is likely to be lowest in the past four years, as not-so-calm surface winds in Delhi will help in dispersion of pollutants.”
The average air quality index (AQI) of Delhi on Thursday was 314 in the very poor range. On Diwali night, November 14, SAFAR has forecast it to be between the high end of very poor to low end of severe category. SAFAR has also forecast that concentration of PM 2.5 would be around 250 µg/m3 on Saturday and would rise to 300 µg/m3 on Sunday, before reducing again.
On the day after Diwali in 2016, PM 2.5 level rose close to 700 µg/m3. In 2017, it was around 350 µg/m3 and in 2018 close to 600 µg/m3. Last year, the PM2.5 levels after Diwali day was around 300 µg/m3, as per SAFAR data.
Wind direction over the city is forecast to be from the northwest on Friday and Saturday, which would cause intrusion of pollutants from stubble burning states, but from Sunday the wind direction would change to easterly, with moderate speed, which would improve the AQI unless firecrackers are burned, the SAFAR forecast said.
Isolated rainfall is also expected on Monday under the influence of a Western Disturbance, which will further help in improving the AQI to lower end of ‘very poor’, as per the SAFAR forecast.
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