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Why is Delhi So Polluted?

Delhi, widely recognized as the capital of India, holds immense political significance in the country. Its strategic importance can be traced back to the medieval era, when it was ruled by the Tomara and Chauhan dynasties. Since then, Delhi has continued to hold a prominent position of power in the Indian subcontinent.

Delhi has consistently been in the public eye, albeit for various reasons. However, in recent years, it has garnered attention for reasons that are far from commendable. The city has been grappling with a host of social, cultural, and environmental challenges. This article seeks to elucidate the primary cause of one of its most severe environmental problems – air pollution. To fully comprehend the situation, it is necessary to first familiarize ourselves with the relevant terminologies.

What is Air Quality Index (AQI)?

Air is a homogenous mixture of different gases. All the gases present in this mixture are in different proportions. Within this mixture, if concentration of some of the gases like Carbon monoxide, sulphur dioxide, nitrogen dioxide etc. increases, then it has health effects on human body. These health effects ranges from minor breathing discomfort to serious lung and heart diseases.

The Indian Ministry of Environment, Forest and Climate Change launched AQI initiative under ‘Swachh Bharat’ in a bid to increase awareness among people in regards to air quality of there surrounding in a format of One-Number-One-Colour Description. So that, its easier for common people to understand the cleanliness of their vicinity.

The Indian Government has categorized AQI in six categories after considering the volume of eight pollutant (PM10, PM2.5, NO2, SO2, CO, O3, NH3, and Pb). The National Air Quality Standards are prescribed as:


What is AQI of Delhi?

The AQI for Delhi is worsening every year since last decade and it ranges from 350 to 480 which is categorized as very poor and severe as per the Indian Government. The live AQI can be found on the Central Pollution Control Board’s website. If we look at the seasonal variations, The AQI start deteriorating in October and is worst during winters. The two major culprits for higher AQI in Delhi out of the eight pollutants, are PM10 and PM2.5.

What is PM10 & PM2.5?

PM stands for Particulate Matter. And the numbers indicate the diameter of the particulate matters in µm (micro-meter). One µm is equals to one millionth of a meter (1/1000000). Here is an image to put this in perspective.


These particulate matters are suspended in the air and causes health hazards when inhaled during day-to-day activities.

Why is Delhi Polluted?

Till now we have figured out that the reason for higher pollution in Delhi can be pinned down to two types of pollutant PM10 and PM2.5 and the presence of higher concentration of these two pollutants around Delhi. Therefore, we mainly need to find the reason behind increased concentration of these particulate matters to get the answer to our question. A study in this regard was conducted by Dr. Mukesh Sharma of IIT-Kanpur in year 2015 which categorized the major sources of PM10 and PM2.5 in simple categories for better understanding. The studies concluded following:


If we broadly categorize them further than following categories emerges:

Combustion Based Pollution

These are ground level sources of particulate matters. Activities like diesel, petrol & Natural gas combustion i.e., vehicular exhaust, cooking & heating, burning of biomass (which can be linked to the crop residue burning, majorly from the state of Punjab), open waste burning etc. Delhi has around 1.18 lakh crore registered motorized vehicles on its roads which means around 643 vehicles per 1000 people in Delhi. All this contributes to 56% of particulate matters suspended in Delhi’s vicinity.

Mechanical Process Based Pollution

The rest of the Particulate matters suspended in air are due to construction activities, dust storms and constant vehicular movement. Vehicular moment results in resuspension of settled particulate matters and therefore contributes to the overall pollution. The industrial sources can be distant from the city itself but the PM particles are transported through air towards the city and therefore results in increase in PM concentration.

What Can Be Done?

A systematic approach towards controlling or preventing the emission of particulate matter can significantly improve the situation in Delhi. Effective measures such as switching to cleaner fuels, implementing laws to regulate vehicular emissions, and utilizing biomass in alternative ways instead of wasting or burning it, can lead to substantial improvements. The Delhi government has already taken steps to create awareness against biomass burning and has implemented laws to regulate vehicular emissions in recent years. However, it is essential that the collective efforts of Delhi’s residents are also mobilized to help solve this problem.

Fatema Kapadia
Fatema Kapadia
Fatema Kapadia is a creative content writer with a curious mindset. She is a graduate of English literature from MSU Vadodara. She is keen on topics related to current affairs, health, and social issues.

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