Delhi air quality post-Diwali: Better than last 3 yrs, but still very poor

Delhi had anticipated the season's worst pollution levels on the morning after Diwali, but the air quality, although "very poor", turned out better than the last three years, according to data of the government's air quality monitors.

The Ministry of Earth Sciences' air quality monitoring service, SAFAR, had earlier predicted that the city's overall air quality index (AQI) would enter the "severe" category between 1 am and 6 am on Monday, primarily due to firecracker emissions, unfavourable weather and a significant spike in stubble burning.

But, Delhi sprung a surprise with air quality sensors recording only a marginal increase in pollution levels even though people continued bursting crackers until late on Sunday night, violating the Supreme Court-enforced two-hour limit with impunity.

While the city's AQI stood at 327 at 11 p.m.. It dipped to 323 at 3.30 a.m., just about when it was expected to enter the "severe" category.

It, however, increased to 340 at 8:30 a.m., as the weather department reported occurrence of shallow fog.

An AQI between 0-50 is considered "good", 51-100 "satisfactory", 101-200 "moderate", 201-300 "poor", 301-400 "very poor", and 401-500 "severe". Above 500 is "severe-plus emergency" category.

Thirty-six of the 37 air quality monitoring stations in the capital recorded their AQI in "very poor" category.

Delhi's air quality was, however, better than satellite towns of Ghaziabad (375), Greater Noida (356), Gurgaon (352) and Noida (375), according to Central Pollution Control Board's data.

Last night, people reported violation of the two-hour window in Malviya Nagar, Lajpat Nagar, Kailash Hills, Burari, Jangpura, Shahdara, Laxmi Nagar, Mayur Vihar, Sarita Vihar, Hari Nagar, New Friends Colony, Hauz Khas, Gautam Nagar, Dwarka among others places.

Residents in Noida, Gurgaon, Ghaziabad also reported extensive fireworks much beyond the timeframe.

People could also be seen bursting crackers before 8 PM, however, the intensity remained low.

The levels of PM10 tiny particulate matter of diameter 10 or less than 10 microns that can enter deep into the lungs had on Sunday reached as high as 515 micrograms per cubic metre in Anand Vihar.

In Wazirpur and Bawana, PM 2.5 levels had crossed the 400 mark.

After last year's Diwali, Delhi's AQI had crossed the 600-mark, which is 12 times the safe limit. The AQI post-Diwali was 367 in 2017 and 425 in 2016.

With Delhi's air quality plummeting to dangerous levels around Diwali every year, the Supreme Court in 2018 banned polluting firecrackers and ordered that only green firecrackers, which is said to cause 30 per cent less pollution, can be manufactured and sold.

But the green pyrotechnics have failed to draw good response both from sellers and buyers, primarily due to lack of variety, limited stock and high prices.

Last year also, people continued to buy the conventional firecrackers and use them.

Delhi air quality improves to 'moderate' from 'very poor' with AQI at 128

Delhi's overall air quality improved on Saturday due to western disturbance and increase in surface wind speed. The air quality index (AQI) for delhi is at 128, improving to 'moderate' category from 'very poor' category a day before.

According to the govt-run System of Air Quality and Weather Forecasting And Research (SAFAR), in Delhi's Lodhi Road area, PM 2.5 was at 215 and PM 10 stood at 221. In Chandni Chowk, air quality was in the 'very poor' category with PM 2.5 at 375 and PM 10 measuring at 355. The old Delhi region recorded the worst air quality in the Delhi region. Around Delhi University, the air quality was in the 'moderate' and 'satisfactory' category. In Noida, PM 10 stood at 156 and PM 2.5 at 110. In Gurugram, PM 10 was moderate at 110 and PM 2.5 was in the satisfactory category and measured at 91.

SAFAR predicts marginal improvement in air quality during the evening.

The improvement in air quality is due to increase in surface wind speed and western disturbances. The increase in wind speed is expected to continue on Sunday which will help maintain air quality. Moreover, stubble burning in Haryana and Punjab has been moderate till now and thus drastic change in air quality is not expected.

On Sunday, the AQI is expected to marginally worsen to 165 in Delhi.

The AQI between the range of 51 to 100 is considered as satisfactory, 101-200 is moderate, 201-300 falls under the category of poor. While 300-400 is considered as 'very poor', levels between 401-500 fall under the 'hazardous category'.

Delhi air quality remains poor for 3rd day, stubble burning may worsen it

The national capital's air quality remained "poor" for the third day on the trot on Saturday and is likely to deteriorate further, even as experts said the situation is better than that in the last few years.

The Centre-run System of Air Quality and Weather Forecasting And Research (SAFAR) recorded the overall air quality index (AQI) at 221, which falls in the "poor" category.

The city's AQI is predicted to deteriorate to 256 on Sunday.

SAFAR said stubble burning in neighbouring states contributed 2 per cent to the total concentration of PM2.5, particulate matter 2.5 micrometers or less in diameter, in Delhi on Saturday and it will increase to 6 per cent by October 15.

Pollution levels will move towards "very poor" by the third week of October, it said.

A senior official said the air quality is not likely to deteriorate drastically for the next two to three days as the wind speed is not enough to transport smoke from the burning of stubble in Haryana and Punjab to Delhi.

While Haryana has recorded 481 cases of crop residue burning till October 11 against 547 in the corresponding period last year -- a decrease of 12 per cent, Punjab has reported an increase of 195 cases -- from 435 in 2018 to 630 in 2019.

SAFAR said the AQI is still much better than the last few years in this time of the year, partly due to enough widespread moisture with relatively warmer temperatures around the surrounding areas of Delhi.

"Delhi's air quality was recorded in the 'satisfactory' category till October 2 and in the 'moderate' category till October 9. It turned poor for the first time in the season on Thursday.

"Last year, the city's air quality had turned very poor on October 7," the official said.

SAFAR said the increased biomass fire counts in Haryana and Panjab are likely to influence Delhi's AQI now.

"The surface wind speed continues to be slow and variable with predominant direction from the West. Under these conditions, air quality is predicted to deteriorate to the middle of the poor category by Sunday. Further deterioration of the AQI is expected by October 14," it said.

Starting October 15, stricter measures to fight air pollution will come into force in Delhi and its neighbourhood as part of the Graded Response Action Plan (GRAP), which was first implemented in Delhi-NCR in 2017.