Windy weather rescues Delhi’s air quality: Cleanest post-Diwali in 8 years for Noida and Greater Noida too

Good weather conditions helped ease the pollution levels in Delhi after Diwali. Despite extensive use of fireworks and increased stubble burning, the city’s air quality did not enter the “severe” category. Wind speeds reaching up to 16 km/h and higher-than-normal temperatures kept the Air Quality Index (AQI) in the “very poor” range, resulting in the second cleanest post-Diwali day since 2015 as reported by TOI.

Following Diwali, parts of south Delhi avoided mass firecracker celebrations, but other areas contributed heavily to pollution. The contribution of stubble burning to the PM2.5 levels increased significantly, rising to 27.61% on Diwali day from 8.4% the previous day.

AQI peaked at 362 on Friday morning but gradually improved to 354 by noon, with an average AQI of 339 for the day. In a TOI report, Anumita Roychowdhury from the Centre for Science and Environment (CSE) attributed the improvement to warmer conditions and reasonable wind speed.

Weather Conditions and Air Quality Improvement

This year’s post-Diwali air quality contrasted sharply with the severe levels recorded in 2020 and 2021, as well as last year’s AQI of 358. While certain areas of South Delhi refrained from extensive firecracker use, many other regions compensated for it. The contribution of stubble burning to PM2.5 levels surged dramatically, increasing to 27.61% on Diwali, compared to just 8.4% on Wednesday and 1.8% on Tuesday.Anumita Roychowdhury, executive director of Research and Advocacy at the Centre for Science and Environment, noted, “Even though the air quality on Diwali was in the very poor category — hitting severe levels during midnight — these conditions dissipated quickly the next day.” She attributed this to the absence of deep winter inversion conditions and the presence of reasonable wind speeds, which contributed to natural ventilation

“Despite the air quality on Diwali being in the ‘very poor’ category, it quickly dissipated to ‘moderate’ levels by the afternoon,” said Roychowdhury. The lack of deep calm winter inversion conditions contributed to this improvement, she added.

Wind Patterns and Pollution Dynamics

Wind speeds of 12 to 16 km/h were instrumental in dispersing pollutants, preventing a more severe deterioration in air quality. By noon on Friday, the AQI had improved to 354, showcasing the positive impact of these conditions. In Noida and Greater Noida, air quality also fared slightly better; Noida’s average AQI was recorded at 274 on Friday, marginally up from 257 on Diwali, while Greater Noida’s AQI stood at 258.

Sunil Dahiya, founder and lead analyst at Envirocatalysts, expressed concern over the future: “In addition to pollution from firecracker bursts, stubble burning incidents in Punjab are on the rise.” He warned that this increase in agricultural burning could further exacerbate pollution levels in Delhi-NCR over the coming weeks, emphasizing the need for immediate action from authorities. Immediate intervention from authorities is crucial to manage this issue,” stated Sunil Dahiya from Envirocatalysts.

Abhishek Kar from the Council on Energy, Environment and Water (CEEW) warned that air quality would remain a concern due to increased stubble burning in Punjab and Haryana. He predicted AQI levels would consistently stay above 350 and occasionally breach the 400-mark in the coming days.

Noida and Greater Noida experienced marginal deterioration in air quality, despite being the cleanest post-Diwali day recorded in the last eight years for these cities. Noida’s average AQI was recorded at 274 on Friday, with Greater Noida’s average at 258.

DK Gupta from UPPCB Greater Noida cited high wind speeds and the lack of winter as factors helping pollutant dispersion. Awareness programs and enforcement drives also contributed to the relatively better air quality.

The overall air quality improved post-Diwali due to favorable weather conditions, but officials emphasized the need for ongoing interventions to manage pollution levels from local sources and stubble burning.

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’, 401 and 450 ‘severe’ and above 450 ‘severe plus’.

On Saturday, the national capital’s minimum temperature was recorded two notches above normal at 17.1 degrees Celsius.

At 8:30 am, the humidity was at 88 per cent.

The weather office has forecast mainly clear skies during the day in Delhi and the maximum temperature is likely to settle at 33 degrees Celsius.

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