Even in worst-case scenario, repetition of Diwali 2016 pollution unlikely: SAFAR

Smog in Delhi after Diwali 2016. (File photo)

New Delhi: While the national capital is already 'under the weather', courtesy poor air quality, the System of Air Quality and Weather Forecasting and Research (SAFAR) has said that the 2016 post-Diwali scenario is unlikely to repeat itself this year.

Even in the worst-case scenario where firecracker emission in Delhi remains same as in 2016, a repitition is doubtful, SAFAR said on Monday.

However, it also said that the air quality on October 20 and 21 will still swing between "severe" to "very poor", with Delhi University North Campus expected to receive maximum pollutants.

At "very poor" level, outdoor physical activities are discouraged, while in "severe" or "emergency situation", even stepping outside should be avoided.

This comes on the heels of the Supreme Court order banning the sale of firecrackers in Delhi-NCR region to curb the growing pollutants in the air, while also fearing a repetition of Diwali 2016.

However, despite the ban, firecrackers are still likely to play spoilsport for respiration, as the low winds and moisture would lead to "stagnation of local pollution" and increase toxicity.

"SAFAR Air Quality Forecast for Diwali-2017" report, based on PM2.5 (or particles with diameter less than 2.5 mm, the major pollutant in Delhi-NCR) count, said the upper air winds, from Indo-Gangetic plains and stubble burning areas, were quite low and unlikely to impact Delhi.

Delhi faced its worst air pollution and smog in 17 years the following day after Diwali 2016, with unabated and unchecked stubble burning in neighbouring states being coupled with additional emissions from Diwali firecrackers bought the PM2.5 volume to over 600 units.

Schools were closed after November 6, 2016 with the OPDs at AIIMS recording 35 percent and Safdarjung Hospital recording 20-25 percent spike in the number of patients with respiratory issues.

The international permissible limit for PM 2.5 is 25 micrograms per cubic metre, while for India it is 60.

Last year, the share of coarser and harmful PM2.5 during Diwali increased by 10-20 percent, making air quality more toxic.

"There is no likelihood of repeat of 2016," said the SAFAR forecast.

The SAFAR forecast for next five days is based on three comparative scenarios, assuming that the additional emissions from the firecrackers are 100 per cent – as that in 2016, it is 50 percent and the third scenario being no additional emission from the crackers.

The forecast considers the wind speed and direction over the period of next five days – Tuesday, October 17, to Saturday, October 18.

The winds transport pollutant, especially from stubble burning regions and Gangetic plains (Uttar Pradesh) to Delhi, thereby affecting Delhi's air quality.

According to SAFAR, since the upper air winds are quite low, any significant impact on Delhi is unlikely.

"Moisture in the Delhi air is increasing and morning temperature is declining. This may increase atmospheric holding capacity of the emissions coming from firecrackers," the report said.

The report further warns that while the wind speed is expected to remain low, the dispersion of emissions from firecrackers would also be slow, leading to stagnation of the local pollution.

"In the case of zero-percent firecrackers, the air-quality may improve a bit, but will not deteriorate," SAFAR said.

Considering the most and least polluted areas of Delhi, SAFAR expects Delhi University (North Campus) to get highest pollutant, followed by Noida, Dheerpur, Mathura Road, Palam, Pusa, Lodhi Road and Aya Nagar.

(With IANS inputs)