Crackers, cars or crop burning? Here's what's causing Delhi's 'severe' air pollution

Studies have shown that one of the most prominent contributors of PM 2.5 in the city is road dust

Delhi's indulgence over the Diwali weekend left the city choked and blanketed by smog over the following days, with the situation worsening to the point that Deputy Chief Minister Manish Sisodia on Tuesday called a high-level meeting with all departments concerned to discuss steps to combat the capital's dangerous pollution levels on a "war footing". 

While Delhi has consistently ranked as one of the most polluted cities in the world, with the latest World Health Organization (WHO) report from May this year ranking the capital as the 11th most polluted city out of 3,000 cities in 103 countries in terms of fine particulate matter or PM 2.5 and at the 25th place in terms of PM 10 levels, the Diwali weekend seems to have put the city on life-support. 

Exactly how bad was Delhi's air quality after Diwali? Media reports citing data available from the Delhi Pollution Control Committee’s website said that the real-time air quality in Delhi had deteriorated severely from Sunday to Monday. According to the data cited by the reports, at 8:20 am on Monday, the PM10 recording at RK Puram was 862 µg/m3, against a prescribed standard of 100 µg/m3. Similarly, the PM2.5 concentration was recorded at 434 µg/m3, compared with a standard permissible level of 60 µg/m3. 

At IGI Airport, PM10 was recorded at 523.45 µg/m3, while the data for PM2.5 was not available. At Punjabi Bagh, PM10 increased eight times, shooting to 842 µg/m3, while PM 2.5 increased six times to around 360 µg/m3.

Crackers are only the immediate problem

According to an IndiaSpend article, a 2016 study by the Chest Research Foundation, Pune, and students from the Interdisciplinary School of Health Sciences of the University of Pune found that popular firecrackers emitted extremely dangerous amounts of particulate matter. 

Citing the study, the report said that six popular firecrackers – the snake tablet, the laad (string of 1,000 crackers), fuljhadi (sparkler), the pul-pul (string sparkler), anar (flower-pot), and chakri (spinning firecracker) – emit particulate matter 200 to 2,000 times the safe limits as designated by the WHO. (Read more: Popular Diwali firecracker emits smoke equal to 464 cigarettes)

Concerns were also raised about the proliferation of Chinese-made firecrackers and their popularity among consumers. A report by the Indian Express said that Chinese fireworks contained potassium chlorate, a highly unstable chemical which could explode with just a sharp jolt. The national daily added that the chemicals used in Chinese firecrackers were also more toxic when compared to Indian fireworks, with the illegally imported crackers often containing higher sulphur and potassium chlorate content and thus causing more pollution. These concerns lead to the Delhi government to enforce a ban on these crackers. 

But what of Delhi's round the year pollution levels?

Moving away from the upsurge in particulate matter and air pollution caused by Diwali, Delhi's battle with its dangerous air quality is nothing new. The current state government has tried to implement an ambitious Odd-Even road-space rationing scheme to combat the menace. But, what exactly has been ailing the city's lungs so to say? 

As reported by the Business Standard during the implementation of the first round of the Odd-Even scheme, an IIT Kanpur report commissioned by the Delhi government showed that a major factor for Delhi’s air pollution is its road dust, which contributes nearly 35 per cent of PM2.5. In fact, according to the report, passenger cars contribute less than 10 per cent of particulate matter; the bigger culprit are heavy trucks. (Read More: Odd-even puzzle: Is Delhi prepared to improve its air?)

According to media reports, the IIT study pointed out the following. The sources of suspended particulate matter PM 2.5 are as follows: road dust (38 per cent), vehicles (20 per cent), domestic fuel burning (12 per cent), and industrial point sources (11 per cent). 

The main sources of Nitrogen (NOx) pollutant were: industrial estates including power plants (52 per cent), vehicles (36 per cent), diesel generator sets (six per cent), and domestic sources (three per cent).

The IIT report also found variations in contribution of different pollution sources in winter and summer months. During winters, vehicles contribute 25 per cent of PM 2.5 emissions, 26 per cent comes from biomass burning. 

While during summers, coal and flyash contribute 26 per cent of PM 2.5, soil and road dust 27 per cent, biomass burning 12 per cent, and vehicles nine per cent. 

Citing a 2007-10 six city study done through the National Environmental Engineering Research Institute (NEERI) at the behest of the Central Pollution Control Board (CPCB), the Economic Times reported that the high PM 10 levels in Delhi were caused more by dust and industries rather than vehicles. 

According to the NEERI report, road dust contributed up to 52 per cent of Delhi's PM 10 levels, vehicles contributed 6.6 per cent and industry's share was 22 per cent. Open burning and other area sources contributed 18 per cent.

Stubble burning by farmers in neighbouring states has also been a contributor to the city's misery. The impact on Delhi's air quality is significant enough that, according to media reports, the CPCB announced a multi-pronged strategy in October this year, which includes satellite monitoring, education of farmers and taking punitive measures under the law to mitigate the impact of the activity.  

Also in October, the Delhi government said that stubble burning in neighbouring states of Haryana, Uttar Pradesh and Punjab were also contributing to the pollution in the city, in stead of the menace just being caused by local phenomena. 

The burning of paddy stubble in farms in Haryana and Punjab across the same month plunged Delhi's air quality levels from "moderate" to "poor" according to data from the CPCB, Delhi Pollution Control Committee and System of Air Quality and Weather Forecasting and Research. 

A New York Times report which looked into the matter found that farmers in Punjab and Haryana were aware that crop burning was causing pollution but they had little or no options at hand given that they could not afford any alternative means to dispose of the leftover straw from their padddy harvest. 

The report said that the government had been promoting a seeder which can be mounted on a tractor allowing farmers to directly plant wheat without having to remove the leftover straw from the fields. However, the farmers who spoke to NYT said that they could not afford such equipment, which the report said would cost a farmer $1,900 if he opts for one of the widely available brands of seeders.

Measures being taken by the government 

1) The Odd-Even scheme shall not be reintroduced. However, according to IndiaToday, the state government has decided to install large outdoor air purifiers and mist sprinklers at five highly polluted locations in the city. 

2) The city's crematoriums would be retrofitted with chimneys to treat the smoke generated by them, the report said. 

3) Pilot project for controlled burning at landfill sites, utilising piping and venting to reduce uncontrolled toxic emissions, would be launched, according to the report. 

4) Public Works Department has been instructed to re-start vacuum cleaning, and sprinkling of water on 1,250 km of roads falling under the agency's purview, the report added. 

5) The CPCB has also started an initiative to track, prevent and legally punish the practice of crop burning in Delhi's neighbouring states.