Delhi Air Quality Descends to 'Very Poor', Worst Yet to Come

Due to the lingering rains delaying harvests, the threat of stubble burning looms large over Delhi's already 'very poor' pollution levels.

New Delhi: On Wednesday, the air quality in Delhi descended to the ‘very poor’ category for the first time this season, according to a report in Times of India.

The air quality index (AQI) value for Delhi on October 16 was 304, according to the Central Pollution Control Board. 

The AQI provides a figure for the level of pollution based on the concentration of eight different air pollutants such as PM 2.5, PM 10, NO2, and so on. An AQI above 300 has been categorised as ‘very poor’ by the CPCB while a value between 201 and 300 is considered ‘poor’.

These standards are considerably higher than global standards. For instance, in the United States of America (USA), the Environmental Protection Agency (EPA), considers an AQI above 100 as ‘unhealthy’ and an AQI value above 300 is considered ‘hazardous’.

In China, an AQI above 300 is categorised as ‘severely polluted’. 

According to CPCB data, on Wednesday, 10 of the 108 cities for which it has data, recorded AQI levels above 300. Loni in Ghaziabad recorded the worst air quality with 358 on the AQI. 

On Thursday, according to the Indian Institute of Tropical Meteorology’s monitoring system Safar, Chandni Chowk recorded PM 2.5 levels of 314. These are particles fine enough to enter our blood stream and are a cause of cardiovascular and respiratory diseases.

No level of PM 2.5 can be considered safe as its presence increases the probability of asthma attacks, bronchitis and other pulmonary diseases, especially for those with a pre existing lung or hearth condition. 

Also read: Claim That Delhi Air Pollution Has Fallen by 25% Needs to be Taken With a Pinch of Salt

Chandni Chowk also recorded a PM 10 level of 258. This pollutant is fine enough to enter and lodge itself in our lungs. 

Every year, in early winter, most of north India sees severe air pollution. In addition emissions from vehicles and factories, and dust, a rise in farm fires or stubble burning also contributes to rising pollution levels. These, coupled with a change in weather patterns – like a fall in temperature and low wind speeds – tend to trap polluted air closer to the ground. 

The farm fires are caused by paddy farmers in Punjab, Haryana and parts of western Uttar Pradesh who burn stubble and loose straw left over in fields after the kharif harvest. This is done to prepare the field for rabi crop. 

This year, according to Safar, farm fires are yet to play a major role in the declining air quality in Delhi. It said that only 5% of the PM 2.5 levels can be attributed to stubble burning.  

Delhi chief minister Arvind Kejriwal reacted sharply to this piece of news, saying that it is “impossible” to determine the contribution of different sources towards air pollution in Delhi. He also said that the Delhi government is doing what it can but the issue of stubble burning is outside its control. 

So far, farm fires have been low due to the delayed withdrawal of the monsoon. Rains in late September has meant that paddy crop still has high levels of moisture, making it unsuitable for harvest in the usual early October window. The Punjab Agriculture University has, in fact, issued an advisory asking farmers to delay their harvest due to the rains on September 27 and 28. 

Balwinder Singh, who is with the International Maize and Wheat Improvement Centre in New Delhi and who recently co-authored a study on crop burning in Punjab and Haryana, told The Wire that the air pollution problem could be much more severe towards the end of October. 

“Harvesting is getting late this year and burning will move into the cooler days of November, which will be more harmful as particulate matter will not disperse in cooler days. Another risk in delayed harvesting is that many farmers will harvest and burn the residue within a short time span towards the time between the end of October and early November, which will increase the intensity of fire events and also particulate matter,” he said.