The story so far : Post-Deepavali, Delhi — and many of the cities in the adjoining National Capital Region — have been enveloped in a familiar pall of particulate matter pollution. The Air Quality Index (AQI) in several cities has breached the 450-mark on a scale of 500. Anything above 400 is categorised as ‘severe’.
How bad is the situation?
Air quality for over a week has been calamitous in most of north India. With the retreat of the southwest monsoon, moisture levels have reduced and the cold dry air that results from the overall drop in temperature with the advent of winter starts to settle down. There is also a significant drop in windspeeds during this time. When windspeeds are over 10-15 kmph and temperatures are warm, fine particulate matter rises and is goes into the higher recesses of the atmosphere. But once the monsoon retreats, and windspeed reduces, pollutants take much longer to disperse. The entire Indo-Gangetic plain, covering large parts of Delhi, Haryana, Punjab and eastern Uttar Pradesh, constitutes an air shed, meaning that roughly the same atmospheric conditions prevail. Therefore, when there is adverse weather, the effect of key sources of particulate matter pollution — road dust, vehicle exhaust from transportation, from the burning of wood for heat and cooking and from heavy industry — that are ever-present through the year become amplified.
What role do crackers and stubble burning play?
The smoke from crackers as well as the metals they contain such as nickel, lead and arsenic have been identified as key contaminants. The Central Pollution Control Board (CPCB) monitors both air and noise levels at several places in the country few days before and after Deepavali to measure this. Since 2017, when the Supreme Court imposed restrictions on bursting crackers, the CPCB reported a reduction of as much as 38% in barium levels in 2020 compared to previous years’ levels. However, there has been no significant improvement in particulate matter pollution as many cities such as Delhi, Lucknow, Kolkata and Bhopal recorded a 60% to 80% increase on Deepavali day when compared with that in previous days of the week. Such a measurement does not account for changes in meteorological conditions or increased traffic observed during festivals, and with crackers being the most discernible variable that is present during Deepavali, all changes in air quality are usually attributed to crackers. The burning of stubble, which poses a unique air pollution challenge in parts of North India, may end up increasing pollution levels on Deepavali. Farm fires this year were set to peak — and there are nearly 4,000-6,000 recorded instances of burning in Punjab, Haryana and eastern Uttar Pradesh on a single day — during Deepavali week. Meteorological forecasts, before Deepavali, had said that in spite of a rise in stubble burning these fires were unlikely to contribute more than 5% of the pollution load. However, on Deepavali, these fires ended up contributing to more than 40% of the load. This was because of a change in the wind direction, which, instead of moving east, turned north-westerly, bringing pollutants from stubble-burning States. Coupled with the fact that wind speeds were near zero in Delhi, this led to a dramatic increase in particulate pollution. Thus, both crackers and stubble add to Delhi’s noxious air, but are significantly influenced by the prevailing meteorology.
What is being done about it?
A major realisation that has come about from years of facing the air pollution crisis is that no State can control pollution in isolation. But it has been difficult to get all States on board. Farmers in Punjab and Haryana have been incentivised to abstain from burning stubble and there are stringent fines to rein in errant ones. However, implementation on the ground is weak. Only a limited fraction — 10-20% — abstain from burning, primarily because burning stubble is the cheapest and easiest option. The fear of political reprisal means that fines are not seriously pursued. However, the need for a joint front has led to the formation of a Commission for Air Quality Management, a full-time body with a Chairman, a core group of members and independent experts.
A paucity of people, who can enforce measures on the ground, and the sheer scale of the problem, which cannot be solved by quick fixes but only through systemic changes, are going to be the key challenges.