However, Air Quality Index deteriorates to ‘severe’

The air pollution day after Diwali this year was much lower than that of the last year. The Air Quality Index (AQI) was recorded at 340 µgm-3 on Monday, remarkably lower than last year’s 600 plus.

The air pollution was remarkably down on all parameteres, viz PM 2.5, PM 10, Carbon monoxide (CO) and Nitrogen dioxide (NO2).

Citing Delhi Pollution Control Committee (DPCC) data, Chief Minister Arvind Kejriwal said the air quality post-Diwali morning in Delhi was recorded much better than those in the past five years.

The Center-run SAFAR said the level of PM 2.5 post- Diwali was much lower this year in comparison to last three years. It has been reported that Delhiites this year refrained from bursting crackers to celebrate Diwali.

In 2016, PM 10 was recorded 3321 µgm-3 whereas this year the value of same pollutant was recorded 485 µgm-3.

According to the Delhi Government, overall AQI recorded in 2017 was 367 and 425 in 2016. Quoting the data monitored by DPCC, Environment Minister Kailash Gehlot said air quality post Diwali was better than that in 2018.

However, the air pollution for the first time in the season deteriorated to “severe” level on Monday.

Situation in National Capital Region (NCR) was bad in terms of air pollution because AQI recorded higher. The satellite towns of Ghaziabad recorded AQI at 378, Greater Noida 364, Gurugram 359, and Noida 375, according to Central Pollution Control Board (CPCB) data.

Ambala, Hisar and Kurulshetra in Haryana recorded AQI at 370, 380, and 377 respectively.

In Uttar Pradesh’ Muzaffarnagar, Moradbabad, Meerut, AQI was  414, 393 and 330 respectively. The AQI in Punjab’s Patiala, Ludhiana, Jalandhar and Khanna stood at 334, 314, 321 and 301 respectively.

On Diwali night, the Delhi Government measured levels of primary and secondary pollutants from 24 different locations where monitoring devices are installed, based on the database prepared on observations of monitors. The Delhi Government claimed that pollution levels were low as compared to the Diwali nights of the previous years.

Evaluating post - Diwali data of 2018-19, DPCC official showed this year, PM 2.5 ranged from 58 µg/m3 to 1070 µg/m3. “The minimum value was observed at 4:00 pm and maximum value was observed at midnight and the location wise minimum concentration was observed at Najafgarh (168 µg/m3) and maximum concentration was observed at Vivek Vihar (687 µg/m3),” a DPCC official said.

The value of same pollutant on post- Diwali day (2018) had fluctuated between 69 µg/m3 and 1560 µg/m3. The minimum value was observed at 3:00 pm and maximum value was observed at 1:00 am.

Another major pollutant which is PM 10, the average concentration ranged from 149 µg/m3 to 1391 µg/m3. The minimum value was observed at 4:00 pm and maximum value was observed at midnight this year, the minimum concentration was observed at Najafgarh (242 µg/m3) and maximum concentration was observed at Vivek Vihar (856 µg/m3) whereas on post- Diwali (2018) the average concentration (for 24 hrs) for PM 10 ranged from 167 µg/m3 to 1859 µg/m3. The minimum value was observed at 3:00 pm and maximum value was observed at 01:00 am.

Pollution monitoring agency also compared values of secondary harmful pollutants - Sox, Nox, Co.

Analysing pollution data of both the years, the DPCC said less fireworks, rigorous night patrolling and enforcement measures to curb instigators reduced the PM2.5 and PM10 levels by 30 per cent on Diwali night this year when compared to 2018.

The decline in emissions of dangerous PM10 and PM2.5 particles across Delhi ranged from 20 to 50 per cent, indicating the air quality was better than previous years, DPCC said in a statement. “The peak level of PM2.5 - tiny particulate matter equal to or less than 2.5 microns in diameter that can enter deep into the lungs and even the bloodstream - was 1,070 micrograms per cubic metre (µg/m3) at midnight. Last year, it was 1,560 µg/m3 -  a reduction of around 30 percent.” The peak levels of PM10, which was 1,859 µg/m3 on Diwali night last year, came down to 1,391 µg/m3 - again a drop of 30 percent,” the DPCC said in a statement.

It is important to mention here that the contribution of stubble burning in Delhi’s air has also increased up to 25 per cent. “The main factors contributing to this year, was high boundary layer wind speed, it helped to flush out and disperse high firecracker emissions. Haryana and Punjab stubble fire counts are increasing, and the transport level wind direction is favorable for plume transport (northwesterly),” said SAFAR.

“Biomass related contribution may touch this year’s peak value (~25%) . AQI forecast indicates improvement  to ‘very poor category’ by Tuesday and a slight increase in wind speed is expected by October 30 and it will help improve AQI marginally to middle end of the Very poor category,” SAFAR added in its air quality forecast.