The capital breathes its most polluted air between November 1 and November 15 when smoke from stubble fires and firecrackers plunges the city into a health emergency, a Delhi government analysis of average levels of PM2.5 (particulate matter) diameter less than 2.5 micrometers) over the past five years have shown.
Analysis by the government’s environment department found that average PM2.5 levels between November 1 and November 15 reached 285ug / m3, classified as “severe” under the regulations of the Response Action Plan. graduated (Grap).
Senior Delhi Pollution Control Committee (DPCC) officials said November 1–15 is the worst pollution time for Delhi, mainly because the city’s air is saturated with smoke from farm fires in Punjab and Haryana. The situation is made worse by the bursting of crackers during Diwali and the adverse winds which bring pollutants from cities in the National Capital Region (NCR) to Delhi.
“The main contributor during this fortnight has been the stubble fires which occur in large numbers in Punjab and Haryana. These fires increase on October 15, but the impact on Delhi’s air reaches its maximum in November, ”said a DPCC official, asking not to be named.
The official added, “Apart from that, for the past four or five years, Diwali has been celebrated either in late October or in the first half of November. Even though last year there was a total ban on crackers, violations have been reported because the ban was announced at the last moment, and also because people bought crackers in towns in the NCR such as as Ghaziabad and Gurugram.
In 2020, Diwali was celebrated on November 14; in 2019 it was October 27, in 2018 it was November 7, in 2017 it was October 19 and in 2016 the holiday was celebrated on October 30.
The trend could also continue this year as Diwali will be celebrated on November 4, the official said.
The analysis focused on how winter pollution levels fluctuate between October and February. Months were divided into fortnights to check pollution levels and focus on particular sources during specific times, so government agencies could plan targeted actions.
The analysis showed that the winter pollution season begins from October after the monsoon recedes. During the first half of October, the average PM2.5 levels were 80ug / m3. As the cases of thatch burning increased and the wind pattern over northwest India changed, average particulate levels also increased, settling at 158ug / m3 in the second half of October. After peaking at 285ug / m3 during the first 15 days of November, PM2.5 levels dropped briefly, reaching 163ug / m3 between November 16 and November 30, before rising again.
Between December 1 and December 15, the average PM2.5 levels were 188ug / m3. With the drop in temperatures, pollution levels have risen to 218ug / m3.
In December, the scientists said, the sources of pollution were mostly local, such as open-air garbage burning, vehicle emissions, and dust from roads and construction. “The peak in the second half of December is very different from what we see in November. This is mainly caused by local factors. Delhi’s internal pollution sources are unable to disperse and remain close to the surface due to cold conditions and low wind speed. Other factors that add to the city’s spike in pollution are crackers bursting during the New Year and also during weddings during this time of year, ”said a second DPCC official.
Officials said this assessment of the city’s fluctuating air quality will help the government target its action against sources of pollution. The city’s first state-level winter action plan also took into account the results of this analysis.
Anumita Roychowdhury, executive director (research and advocacy) at the Center for Science and Environment (CSE), said their own analysis also showed that Delhi’s winter pollution peaks are increasing in two phases – once at the start of winter, then again at the peak of winter.
“You have to understand that winters are delicate because weather conditions do not allow easy dispersion of pollutants. Even then, the government can guarantee that year-round actions and targeted emergency actions can help reduce peaks, ”Roychowdhury said.
She added: “You can’t come up with a quick fix, but agencies can make sure fuel isn’t added to the fire. The weather may not be right, but at least we can control emissions from local sources so that the pollution load does not increase. We need a holistic winter plan, but we also provide emergency measures during peak pollution days. “