Smog - The Crossover Noone wanted

Delhi City, looking photogenic for the common man.

You see this sight, early in the day or sometime in the evening, and perhaps go ‘Wow, pretty photogenic’. Here is the truth- whether or not you do this, this sight is nowhere close to normal. In technical terms, it is called Photochemical Smog, or simply Smog. But how does this form, and what does it do?

How does Tropospheric Ozone forms.

Tropospheric Ozone, a toxic gas, forms by this process. It is usually found in road transportation, solvent release in drying paints, glues and in petrol distribution and handling. It is the main pollutant behind smog, which has another process behind it.

Smog (Smoke + Fog) is formed when the mixture of multiple primary and secondary pollutants, mainly composed of Nitrogen Oxides and Ozone from vehicle exhausts, interact with strong sunlight. It produces Volatile Organic Compounds, which oxidize Nitrogen Oxide into Nitrogen Dioxide without breaking down the ozone molecules, which leads to buildup of ozone near the ground level alongside the formation of a brown hue smog. It is usually affected by Climatic Conditions and Local Topography, the use of fossil fuels (for the main pollutants are from the fuels being burnt) and Population Density (for Smog is usually found in crowded cities).

What happens when Smog over-accumulates? It becomes a bane that keeps on giving!

This phenomenon ultimately leads to a process called Thermal Inversion, where Cool air is trapped between a layer of Warm ‘Inversion’ Air. As seen in the above picture, in Normal Conditions, air takes away all the pollutants from the warm surface air through the cooler layers and away into the atmosphere. But, with the presence of smog, the warm air becomes the polluted layer, and an even warmer layer of air forms, preventing the rising of pollutants and creating a convection current – like scenario which traps the pollutants at ground level.

This issue is dire and has a few solutions such as encouraging more public transport, using renewable energy sources, using catalytic converters, reforestation etc. While Covid did allow for a temporary recovery, such solutions and more need to be implemented quickly and efficiently, without which smog could very well become the new gassing chamber – a deadly enough a threat to change our behaviour.

By Dhanvanth Prassana Venkatesh