Chandigarh, Oct 15 : The 2025 floods in Punjab and Haryana have served as an 'unplanned intervention' that lowered rice crop residue fire activity as high as 77 per cent, leading to a 15.5 per cent reduction in Delhi's average PM2.5 levels this month in comparison with last year's, an analysis said on Wednesday.

The analysis using the data of the Central Pollution Control Board (CPCB) and NASA revealed that with stubble burning curtailed, Delhi's PM2.5 still remained above 50 µg/m3, revealing a significant background load from other sources -- traffic, industries, and dust re-suspension.

Fine particulate matter is defined as particles that are 2.5 microns or less in diameter (PM2.5). Prolonged exposure to levels above 50 μg/m3 can lead to serious health issues and premature mortality.

'The analysis that examines the relationship between stubble burning in Punjab and Haryana and PM2.5 levels in Delhi during the first 12 days of October for two consecutive years -- 2024 and 2025 -- underscores that reducing farm fires alone can yield immediate benefits, but structural air quality gains require multi-sectoral emission control beyond agriculture,' a researcher told IANS.

This year was marked by widespread floods in Punjab and scattered in Haryana, which significantly disrupted agricultural activities and crop residue management.

'This climatic anomaly provides a unique lens to understand how changes in stubble burning influence Delhi's air quality,' remarked the researcher, requesting anonymity.

The researcher pointed out that the 77.5 per cent reduction in total stubble burning events this month can be directly attributed to the massive floods in Punjab and Haryana.

The flooding delayed harvest cycles, waterlogged fields, and reduced dry residue availability, making it physically impossible for many farmers to conduct residue burning. This resulted in an involuntary but drastic suppression of fire activity across both states, said the researcher.

Likewise, the drop in stubble burning coincided with a 15.5 per cent reduction in Delhi's average PM2.5 levels during this period. 'This natural experiment underscores a strong causal link between biomass burning intensity in upwind states and air quality deterioration in the National Capital Region (NCR),' pointed out the researcher, adding 'fewer fires led to cleaner air, even without major policy or enforcement changes'.

In 2025, daily correlation weakens as non-agricultural sources (vehicular, industrial, dust, etc.) dominate residual pollution levels.

'The comparison data between October 2024 and 2025 reinforces that controlling agricultural burning is critical for Delhi's clean air, but sustained air quality improvement will depend on addressing urban and industrial emissions as well,' added the expert.

The total stubble burning cases in Punjab were 392 from October 1 to 12 in 2024, and they fell to 105 during this period in 2025, a fall of 73.2 per cent.

In Haryana, the stubble burning cases were 387 from October 1 to 12 in 2024, which reduced to 70 during this period in 2025, a fall of 81.9 per cent. During this period, the average Delhi PM2.5 was 60.79 in 2024 and this year it was 51.48, a reduction of 15.5 per cent.

With 31 more cases recorded on Tuesday, the highest single-day spike of the season in farm fires, Punjab has so far recorded 165 farm fire incidents.

According to data from the Punjab Remote Sensing Centre, Amritsar topped the list with 68 reported cases of stubble burning, followed by Tarn Taran, which saw 47 incidents.

However, Haryana has witnessed a 97 per cent decline in stubble burning incidents between September 15 and October 13 this year compared to the same period last year.

Officials attributed the drastic reduction in Haryana to strict enforcement against offenders. Agricultural experts say that to quickly clear the field for the next crop, the farmers burn the leftover paddy straw rather than using the traditional method of clearing it by hand or adopting the option of sustainable millet cultivation to break the paddy-wheat crop rotation introduced during the Green Revolution era (1967-1978).

Besides smoke from burning crop stubble, vehicle exhaust, and factory emissions combine every winter to blanket Delhi in a choking haze, largely owing to reduced wind speed after the withdrawal of the monsoon and cold winds from the Himalayas.

(Vishal Gulati can be contacted at vishal.g@ians.in)

/IANS