With air quality in Delhi hovering between severe and very poor levels in the past 10 days, and particulates consistently emerging as the prominent pollutants, the System of Air Quality and Weather Forecasting and Research (SAFAR) has become the first agency to sound the alarm bells.
On Monday SAFAR, which comes under the the Ministry of Earth Sciences, issued a forecast projecting that peak particulate matter (PM) levels would spike considerably when compared to the levels last Diwali, owing to weather factors alone.
According to the health advisory issued by SAFAR, “Everyone should avoid all physical activity outdoors; people with heart or lung disease, older adults, and children should remain indoors and keep activity levels low….” from the night of November 11 to the afternoon of November 12.
The agency said this can be assumed as a “health warning for all” as it can pose a “serious risk of respiratory illnesses in general public (due to) prolonged exposure”. Particulate matter refers to tiny particles in the air that can penetrate the lungs and cause severe health hazards. The finer PM 2.5 particles can penetrate deeper into the respiratory tract, causing graver health issues.
PM levels usually peak a day after Diwali. From a peak of 450 micrograms per cubic metre on the day after the festival last year, PM 10 levels this year are expected to go up to 956 micrograms per cubic metre on November 12. PM 2.5 levels are expected to shoot up from last year’s 250 to 450 micrograms per cubic metre this year.
Officials said safe limits for PM 2.5 is around 60 micrograms per cubic metre while it is 100 micrograms per cubic metre for PM 10.
According to SAFAR scientists, Noida and Delhi University will witness the highest pollution while Lodhi Road and Mathura Road will see the least pollution.
Peak pollution hours will begin at about 1 am on November 11. This forecast is based on prevailing weather conditions, assuming that the number of crackers set off remain the same as last year. Project director of SAFAR Dr Gufran Beig said, “In all likelihood, air quality this Diwali is going to be inferior compared to last year, primarily due to weather factors. Cooler temperature and downward shift of the inversion layer means Delhi will breathe severe air for at least a day immediately after Diwali.”
Dr Beig added that this, in turn, may increase the rate of cooling further. “Under this condition, particles emitted from fireworks will sit on water droplets and cause them to multiply, resulting in more particles in suspended air .This process is called secondary particle formation. It is likely to happen on November 12 and 13,” he said. This, according to scientists, will lead to dense haze formation.
Scientists said that this year, the spike in particulates has been of particular concern.
“Every year PM levels rise before Diwali. This year, the rise has been steep. We are also concerned with rising NO2 levels. People come out on the roads to shop prior to the festival and on Diwali, which leads to increased vehicular intensity. This spike in NO2 and PM levels together is a particularly lethal condition,” said Anumita Roychowdhury, head of the air pollution campaign at Centre for Science and Environment.