Air pollution in the National Capital Region (NCR) is a year-round problem. However, with the onset of every winter the level of air pollution becomes visible for all us to see when smog and fog descend over the capital. Not surprisingly, public debate on the quality of air in the capital and the country acquires rightly deserved heightened attention from reporters.

All stakeholders – the ordinary public, politicians, environmental activists, media, etc. - join in a highly contentious debate that seems like a blame game, and it runs for the next two to three months.

The media does its job by putting the air pollution and smog on the public’s agenda as much of the contestation takes place in TV studios, on the pages of the newspapers, and in 140-character tweets. We ask why PM Modi is not doing anything about it? Is Swach Bharat only jumla?  Why is CM Kejriwal not doing anything? Why are the CMs of Punjab, Haryana, and Uttar Pradesh not banning the burning of kharif crop-stubs in the fields?

Months go in blaming our favourite target of derision before we and the media move on to the next topic of highly politicized contestation. Nothing serious is done, and we come back at it again next winter when smog descends once again on the capital.

For the media, pollution of all varieties and the winter smog must not be primarily a political issue; it is first and foremost an environmental science issue that requires the clear-headed practice of science journalism. Blaming the politicians and the farmers will not solve the problem. At the heart of the problem is the need to explain to the public the chemistry of smog.

The media must focus its attention on helping people understand the science in an accessible form so that all of us can see clearly how we contribute in creating this problem. It may even help the authorities come up with an effective public policy response, instead of short-term gimmicks such as the odd-even schedule.

We know from the report of the Central Pollution Control Board that the air quality of NCR, which is bad year-round, gets worse in winter. The main pollutants are Sulfur Dioxide (SO2), Nitrogen Oxide (NO2), Carbon Monoxide (CO), Ozone (O3), Benzene, Benzo Alpha Pyrene, Lead (Pb), Nickel (Ni), Arsenic (As), and suspended particulate matter in the air that includes dust and carbon soot from burnt fuel and crops.

Except for Ozone, all other pollutants come mostly from the burning of fossil fuels used in vehicles and power plants, and seasonally from burning crops. Ozone, like acid rain, is produced as result of chemical reactions in the air, and moisture -laden cold air in winter plays an important part in the formation of smog.

The problem of smog was addressed in most major cities such as London, Los Angeles, Paris, and now in Beijing, by checking Ozone formation. There is no crop burning around these cities. To address the issue, people need to know the chemistry of smog.  

Smog is different from fog, which is merely moisture laden cold air. Ozone formation is a key stage in the formation of smog. The NO2 produced from the burning of fossil fuels when is exposed to ultra violet rays in sunlight light gets converted to Nitrous Oxide (NO) and a free oxygen atom, which then combines with Oxygen gas (O2) to form Ozone (O3).

Under normal circumstances the Ozone instantly reacts with available NO to revert to Nitrogen Dioxide and Oxygen gas. This cycle keeps repeating, keeping Ozone at the ground level in check.

However, the Ozone cycle gets disrupted when volatile organic compounds such as Benzene (C6H6) and Benz Alpha Pyrene are present in moisture-laden cold air. The presence of volatile organic compound disrupts the Nitrogen Dioxide-Ozone cycle, as it competes with Ozone to react with the Nitrogen Oxide. As consequence, there isn’t enough Nitrogen Oxide to convert Ozone back into Oxygen gas.

In addition to playing a role in smog formation, these volatile organic compounds are known carcinogens as well. They mostly come from vehicles, especially diesel vehicles. So, the key culprit in the formation of smog is vehicle exhaust, especially from diesel vehicles, that includes large amounts of volatile organic compounds such as Benzene and Benz Alpha Pyrene.

The smoke from the burning fields in the neighbouring states must not be blamed for the smog. Although the smoke from kharif crop-stub burning contributes significantly to the increased particulate matter, especially of smaller PM5 and PM2.5 size that end up in our lungs, the air people in Delhi breathe includes more than that. It includes dust, carbon soot, benzene, ozone, and nano-particles of heavy metals such as lead, arsenic, nickel. Most of these pollutants are produced locally in Delhi by millions of vehicles running on the roads of the national capital 24X7, and the power plants.

The pernicious effect of volatile organic compounds does not get much attention in the media coverage. The solution to the smog in winter and the year-round poor quality of air in Delhi does not lie in merely getting the farmers to stop the practice of crop burning, which nonetheless should be done ASAP. It will help reduce the particulate matter from burning crops.

But the problem of smog will require nothing short of the phasing out of all diesel vehicles first, and then phasing out petrol vehicles and coal-fired power plants. And the media should do its job in educating the public rather than helping foster the political blame game.