Like every year, the debate around pollution in Delhi is taking its course. Every year, State and Union Government promises different projects and plans to control the AQI in Delhi and like every year, Delhi has become a gas chamber again.
With AQI in the Delhi-NCR region is galloping above severe levels. The Supreme Court of India on Saturday urged the Delhi and Central Government to take “emergent measures”, including the imposition of lockdown in the national capital. The Apex Court also slams both State and Central Government for “bashing farmers” over stubble burning every year even though there are several other major contributors to the hazardous air quality.
Understanding Pollution In Delhi
Most polluted regions are concentrated in the northern belt of India due to many geographical and industrial factors. Every year, a blanket of heavy smog covers up Delhi-NCR after Diwali, causing many respiratory problems, burning of eyes and reduction of visibility.
Every year the headlines surround firecrackers, stubble burning and other industrial factors like polluting industries around Delhi and construction wastes.
But, why do only Delhi-NCR suffers from this severe problem and not other cities like Mumbai and Chennai that are more industrialised?
Chennai is also known as the Automotive Capital of India. Many big automotive companies have their production setup in Chennai like Ford, Hyundai, BMW, Volvo, Ashok Layland, Force etc. Tamil Nadu is also known as the Industrial Powerhouse with many petroleum refineries, heavy industries, more than 700 MSMEs & many coal-powered power plants. Still, the air quality in Tamil Nadu is breathable with moderate particulate matter.
Is, burning of crackers, stubble burning and industries are the only reasons behind the degrading air quality of the nation’s capital?
Let us look at some geographical factors behind this.
Geographical Features
Smog creation is a unique characteristic of Delhi and this is because of a geographical phenomenon known as Temperature Inversion. It is a phenomenon in which the air located on Earth’s surface behaves inversely.
To understand this, let us understand some characteristics of the Troposphere. Generally, with an increase in height in the troposphere, the temperature decreases. This means air closer to the Earth’s surface will be warmer than the upper layer. The warmer layer expands and moves upwards, thus maintaining air movement & as a result pollutant doesn’t get concentrated.
In the case of Temperature Inversion, the layer of air close to Earth’s surface becomes cooler than the upper layer. This happens during winters as the surface doesn’t get warm from Sun’s heat, making the lower layer also cold. Cold temperature limits the lower layer of air to expand, restricting air movements and increasing the concentration of pollutants on the lower layer.
Temperature Inversion condenses the atmospheric humidity in fog. Fog mixes up with pollutants converting into smog (smoke+fog).
Winters in Northern India are extreme, causing Temperature Inversion. As a result, Delhi’s pollution increases by 40-80% during the winter seasons.
Apart from Temperature Inversion, wind speed and wind direction also play a critical role in the formation and dissipation of smog. Horizontal wind flow can throw away the pollutants to other areas, reducing concentration in one area.
Wind Factor
As per weather & climate, on average, the least wind is seen in November in Delhi. The wind speed comes down to 1/3 of summers in winters, causing a pollution trap. During winters, North-West India and the Tibet region experience high pressure and the Indian Ocean experience low pressure. It is the characteristic of winds to flow from high to the low-pressure areas as a result the direction of wind flow is from North West to South East, this also brings dust & sand particles from the Thar Desert to the Indo-Gangetic plains.
The emission of SO2 from thermal powerplants around Delhi also get concentrated in and around Delhi-NCR.
This geographical misfortune is visible around the globe in cities like Los Angeles of the USA and Ulaanbaatar of Mongolia.
Other industrial cities like Chennai and Mumbai doesn’t face this problem as they have the geographical benefit of regular land breeze and sea breeze which restrict any pollutant concentrate, other than this, Southern Indian and coastal areas usually have high temperature, thus reducing the chances of Temperature Inversion.
Conclusion
The geographical disadvantage that the capital face is something which we cannot work at. It doesn’t mean that there is no way to bring back the AQI under breathable levels.
The Centre for Science and Environment (CSE) which has been monitoring real-time pollution data generated by the Indian Institute of Tropical Meteorology explained that among the local sources of pollution, vehicles have contributed more than half of Delhi’s particulate pollution between October 24-November 8.
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This is followed by household pollution that has ranged between 12.5-13.5%, industry (9.9-13.7%), construction (6.7-7.9%), waste burning and road dust (each varied between 4.6-4.9% and 3.6-4.1%, respectively).
Shutting schools and lockdowns are just temporary ways that will not produce any permanent solutions. Government should control different pollution sources, promote green fuel and control emissions. Both the Government, at the State and Centre should work together and stay away from dirty politics.