An analysis of Central Pollution Control Board data has revealed that the air quality in Delhi in November this year was worse than in 2019, reported PTI.

The data showed that the 30-day average air quality index, or AQI, in November 2020 was 328, which falls in the “very poor” category, while it was 312 this month last year. An AQI between zero and 50 is considered “good”, 51 and 100 “satisfactory”, 101 and 200 “moderate”, 201 and 300 “poor”, 301 and 400 “very poor”, and 401 and 500 “severe”.

The Capital also recorded nine “severe” air quality days in November, the maximum number of such days in the month in four years. There were seven “severe” days in November last year. There were five such days each in November 2018 and 2017.

This year’s pollutions levels also breached the emergency threshold twice in November as smog enveloped the Capital for days. The air quality is considered in the “severe plus” or “emergency” category if PM2.5 and PM10 levels persist above 300 µg/m3 and 500 µg/m3, respectively, for more than 48 hours, according to the Graded Response Action Plan.

Pollution had worsened on Diwali and the day after and was at the maximum level in the past four years despite a ban on the sale and use of all kinds of firecrackers till November 30. According to the Ministry of Earth Sciences’ SAFAR, or System of Air Quality and Weather Forecasting And Research, which reports real-time figures, the overall AQI in Delhi had struck 545 in Delhi at 9 am on the day after Diwali. The AQI was at 423 at 5 pm on the day of the festival.

Meanwhile, on Tuesday, the AQI was in the “very poor” category at 352, according to the Central Pollution Control Board. The AQI in satellite towns of the National Capital Region was also poor with Gurugram’s Gwal Pahari reporting 303 at 11 am. It was 507 in Noida’s Sector 62 at 11 am.

On Delhi’s pollution this year, Kuldeep Srivastava, the head of the regional forecasting centre of the India Meteorological Department, said the reason was lesser precipitation as compared to last year. “The monsoon withdrew around October 10 last year, while the wind system receded early this year, around September 23-24,” he said, adding that the other major reason for the pollution was large-scale stubble burning.

In Punjab alone, the instances of stubble-burning had touched 76,590, the highest in the last four years. It was 55,210 last year. The incidents of stubble burning were at the peak between November 4 and November 7 of 2020, an Indian Agricultural Research Institute official said.

“It was a bumper harvest this year, so the amount of crop residue was also large,” the official said. “Also, it was a cloud-free season this year as compared to last year. The biomass was drier and prone to burning.”