Delhi breathes easy after long as rains wash down pollutants. What next?

Delhi and its adjoining areas are breathing easy!

Owing to good rain in August, the air quality index (AQI) in Delhi averaged among the best in recent times so far.

The data shows the average AQI from August 1 to August 24 in the city was 70, the lowest since 2020, the year the pandemic came and when it averaged 64.

The average AQI in August last year was 116, in 2022 it was 93, and in 2021 it stood at 107.

The India Meteorological Department (IMD) data shows till August 23, Delhi had 21 rainy days. The previous occasion when August had a higher number of rainy days was in 2012, when 22 were recorded as “rainy days”, according to the data from the Safdarjung Observatory.

With the monsoon expected to last longer in 2024, at least well into September, there is a good possibility that the AQI will remain tolerable for the next few weeks.

So far so good, but the big question is if the good times will last long? Or with the advent of winter, and the stubble-burning season, will the air worsen?

Sunil Dahiya, analyst, Centre for Research on Energy and Clean Air (CREA), told Business Standard the drop in air pollution was not because of systematic and comprehensive efforts to reduce emission load from polluting sectors such as power generation, transport, waste burning, or construction. So it is less likely that the gains will be sustained, he added.

One big factor in air pollution in Delhi, particularly during winter, is smoke emanating from paddy fields due to the burning of stubble in Punjab, Haryana, and western Uttar Pradesh.

Here too, the data shows that progressively incidents of stubble burning have come down, though it has not finished.

According to the data from the Indian Council of Agricultural Research-Indian Agricultural Research Institute, last year from September 15 to October 29, the number of stubble-burning incidents in Punjab, Haryana, the National Capital Region (stretching into Uttar Pradesh and Rajasthan), and Delhi came down to 6,391 as against 11,461 in 2021 and 13,964 in 2022.

A big determinant of the severity of stubble burning is the period when paddy is planted in the three states that surround Delhi.

If paddy is sown early, it matures early, giving farmers ample time to treat their fields for the stubble left after harvesting.

However, if the window is short between paddy harvest and wheat sowing then farmers are left with little option other than to burn the stubble.

One prime factor for the window being short is the twin acts of the Punjab Preservation of Subsoil Water Act, 2009 (PPSWA), and the Haryana Preservation of Subsoil Water Act, 2009 (HPSWA), which prohibit the paddy sowing ahead of a designated time.

The PPSWA bars raising paddy nurseries before May 10 and its transplantation not before June 10. The corresponding dates in the HPSWA are May 15 and June 15.

This year, most locals and experts say, paddy sowing in both Punjab and Haryana was late in reaching the maximum point because the rains arrived late.

“June was almost dry and in the true sense, monsoon picked up pace over Punjab and Haryana in late July. Therefore, my estimate is barring few farmers, most might have waited for the rains to arrive before sowing,” a prominent farmer leader said.

Palak Balyan, research lead, Climate Trends, said if the meteorological conditions remained favourable and open biomass burning was minimised, “we could expect continued improvement in air quality”.

“Favourable weather, such as higher wind speeds and rain, can help disperse pollutants, while reduced biomass burning limits one of the major sources of air pollution. However, during winter, lower temperatures and a shallower boundary layer can lead to increased pollution concentrations due to reduced dispersion,” Balyan said.

The Commission for Air Quality Management in the NCR and Adjoining Areas (CAQM), which came into existence in 2021, has, meanwhile, initiated measures to keep the air in Delhi clean. It has set a much higher target of 45 million plantations for the NCR during FY25 by various bodies in the state-government academic and educational institutions.

In August the CAQM issued an advisory to all Resident Welfare Associations (RWAs) and other residential societies in Delhi to provide electric heaters or other suitable implements to the security and other service staff employed by them, aimed at curbing open burning.

The Commission has directed urban bodies, including the Municipal Corporation of Delhi and New Delhi Municipal Council, to increase parking fees for private vehicles from November 1 to encourage the use of public transport.