Not only Delhi, the entire Indo-Gangetic Plains were battling “very poor” air quality, according to data from the Central Pollution Control Board (CPCB) in its air quality index (AQI) bulletin on Friday, and several of these cities were bordering on “severe” air as meteorological conditions remained hostile for a second day in a row.
Since Thursday, winds reduced over the region and their direction become variable, shifting to northeasterly for a few hours and northwesterly for the rest of the time. This led to the entire stretch -- Panipat, Kurukshetra, Hisar, Gurugram, Greater Noida, Ghaziabad, Faridabad, Fatehabad, Bulandshahr, Bhiwadi, Bahadurgarh, and Ballabgarh, among others -- recording “very poor” air on Friday, underlining once again that its not just the national capital but the entire Indo-Gangetic Plains (IGP) “air shed” that needs urgent help.
The air shed is a region in which the atmosphere shares common features with respect to dispersion of pollutants. In other words, a region that shares air flow.
India Meteorological Department’s Silam (atmospheric dispersion model), a new feature on the IMD website, showed almost all of northwest India, particularly Haryana, Delhi and Uttar Pradesh impacted by high PM 2.5 (fine, respirable pollutants) concentrations ranging from 200 to 500 micrograms per cubic metres.
“This is typical of October in the entire region. The monsoon withdraws, and then winds gradually become calm, there is no precipitation or any other western disturbance which can disperse the pollution. We are seeing the same thing now. Since yesterday, there is hardly any wind in the region so whatever pollution, both from local and regional sources and from specific sources like crop stubble fires, remain accumulated. We don’t expect an improvement for Saturday and Sunday, but we are not expecting air quality to deteriorate to ‘severe’ either,” said Vijay Soni, a scientist in IMD’s air quality management division.
Data with System of Air Quality and Weather Forecasting and Research (SAFAR), Indian Institute of Tropical Meteorology (IITM) ,which is used for analysis by CPCB, suggested that stubble fires in Punjab and Haryana were contributing to 17% of Delhi’s PM 2.5 load. There were 1,213 fire points recorded by SAFAR on Thursday.
The issue of trans-boundary transport of pollutants was highlighted by scientists in 2016 when IIT-Kanpur, in its source apportionment study for Delhi, said air is more toxic in winter than in summer in the Capital; and that the single most important component was secondary particles, which accounted for about 28% of total PM2.5, and combustion-related carbon accounted for about 23%. The study pointed out that secondary particles form precursor gases, which are emitted from far distances from large sources.
Though the National Clean Air Programme (NCAP) mentions contribution from sources outside Delhi due to winds carrying pollution with the incoming air towards Delhi-NCR, indicating the regional aspect of air pollution, the focus of the Union government’s pollution fight has been largely city-specific.
According to a webinar on a review of NCAP implementation held in September by Union environment minister Prakash Javadekar, air pollution action plans for 122 cities have been approved. These focus on management of pollution hots pots, public transport and fleet modernisation, paving of roads, cleaner fuels for industries, etc. But these are yet to be implemented. NCAP was launched in January last year and has a target of 20% to 30% reduction in PM 2.5 concentrations over 2017 annual levels in over a hundred cities.
“The entire IGP is an ‘air shed’ because it’s a low-lying area stretching from Indus river in Pakistan up to Bangladesh. There are Himalayas to the west and the altitude changes in the region below IGP. Meteorological factors are very similar in the entire region and they need common interventions, otherwise it’s very difficult to see any significant improvement in air quality. Every October, the boundary layer here drops and close to 700 million people are impacted by poor air,” said Sagnik Dey, associate professor, IIT-Delhi, who is doing a World Bank project on cost effective air pollution interventions for the region.
“Satellite data studied by us shows there has been a marginal improvement in annual air pollution concentrations in India in the last two years. This year, I am expecting that we will not see a deadly smog like we saw in 2016. Some actions have been taken like the Ujjwala scheme to provide subsidized LPG or improvement in technology of brick kilns. But we need to see how many are using the scheme, what’s the implementation on ground. NCAP needs an ‘air shed’ approach, where the entire region has a common air pollution mitigation plan,” he added.
