Half of Delhi pollution caused by vehicles! Here are three ways to clean the city’s mobility system

As per a 2018 study by ARAI and TERI, motor vehicles are the primary source of pollutants within Delhi and contribute to about 40 percent of PM 2.5 emissions — one of the key reasons for the city’s toxic air

As the Air Quality Index (AQI) in the National Capital improves from ‘severe’ to ‘very poor’ on the System of Air Quality and Weather Forecasting and Research (SAFAR), so does the issue of ambient air quality in Delhi. That’s because the conversation around air pollution in Delhi starts with the onset of winter, coincides with Diwali and stubble burning, and ends around the start of the New Year with the change in weather and stubble burning.

However, the question is: Is Delhi’s air pollution only a three-month issue? Unfortunately, the answer is no.

Let’s take a look at some data to get some perspective on Delhi’s air quality — the National Capital had its first ‘good air’ day of 2021 in October, thanks to a heavy downpour. In 2016 and 2018, Delhi has not seen even a single ‘good air’ day. In 2017 and 2019, only two such days were reported. Last year, when the country was under lockdown with limited economic activities, even then, Delhi experienced only five ‘good air’ days. Therefore, air pollution is a year-round problem in Delhi that gets noticed only in winters.

We keep talking about Delhi’s air quality, but air pollution is not restricted to the capital alone. As per the monitoring network IQAir, nine of the world’s ten most polluted cities in 2020 were in India. Similarly, a report by the Energy Policy Institute at the University of Chicago (EPIC) found that all of India’s 1.3 billion residents face annual average pollution levels that exceed guidelines as set by the World Health OrganiSation (WHO). The study also estimated that around 52 crore Indians have reduced life expectancy due to air pollution. Therefore, air pollution is a major public health issue in the country, impacting over 40 percent of our population.

Why can we not clean something as basic as the air we breathe? One may argue that there is a lack of awareness around air pollution in the country which could be the reason. But, what is stopping Delhi, which is often in national and international news due to its air quality, from cleaning its air?

To understand this, we first need to focus on what pollutes Delhi’s air.

There are many reasons for air pollution, but one of the key reasons for Delhi’s toxic air is PM 2.5 — an ultra-fine particulate matter size of 2.5 micrometers. To understand in simple terms, PM 2.5 is 40 times smaller than human hair. Due to their small size, they can travel deep into our bodies and infiltrate our lungs and even our bloodstream, causing severe diseases like lung cancer. The levels of PM2.5 are considered “good” when they are below 50 and “satisfactory” when the level is below 100. Currently, in Delhi, the levels are almost 400.

So, what are the sources of PM2.5 emissions? In the case of Delhi, there are two kinds of sources — internal and external. Internal sources are the emissions that happen within the city such as transport, waste burning, etc. While, external emissions are those happening outside Delhi, like the stubble burning in the neighbouring states. The proportion of internal to external sources keeps on changing, but is seen maximum during the Diwali and stubble burning phase. However, the biggest challenge to Delhi’s air quality is the emission from the transport sector.

A 2018 study by ARAI and TERI estimated that motor vehicles are the primary source of pollutants within Delhi and contribute to about 40 percent of PM 2.5 emissions. Interestingly, a recent study by the Centre for Science and Environment (CSE) estimated that motor vehicles accounted for more than 50 percent of pollutants emitted from within Delhi during the early phase of winter this year, i.e. from 24 October to 8 November. The other important elements are stubble burning or smoke from firecrackers during Diwali. However, motor vehicle emissions happen all around the year, making it the most crucial and continuous source of pollution in the city.

Therefore, to clean Delhi’s air, the focus should be on cleaning its transportation system. Delhi can achieve this by following three-pronged strategies:


The first and foremost strategy is solving the problem’s source, which means avoiding the need to travel long distances using motorised transport. This can be done by integrating land use and transportation. For example, Dwarka in Delhi was planned as a sub-city to house one million people. Today, most of the Dwarka residents either travel to Gurugram or go to central Delhi for work.

So, the easiest way to solve the issue would have been a mixed-use development instead of focusing predominantly on single-use residential development. Therefore, an integrated transport system could have given a different look to the sub-city.


Shifting the focus and priorities towards sustainable modes of transport is another important aspect of reducing vehicular emissions. Delhi has the highest area under roads compared to other metros in the country. It also has a maximum number of automobiles in the country.

Historically, the city has mostly focused on solving congestion by widening roads and building flyovers/underpasses, but neither the congestion has reduced nor the travel speed has improved. However, what has gone up is the transport emission. Therefore, it is not rocket science to understand that more roads mean more vehicles, and more vehicles mean more emissions of toxic gases. So, instead of building more roads, Delhi should focus on creating streets that promote safe walking and cycling and double the existing bus fleet.


Improving the quality of fuel and vehicles is also an important strategy in reducing the emission for this sector. In the past, Delhi did try reducing emissions by transitioning public transport and paratransit vehicles fuel to CNG. However, the benefits from this transition were quickly offset by the significant increase in private vehicles. Therefore, switching to zero-emission vehicles like electric vehicles (EV) will be an important move towards reducing tailpipe emissions in Delhi.

Reforming the parking management system along with creating low emission zones will further increase the uptake of electric vehicles in Delhi.

The current state government in Delhi is taking some innovative and progressive steps to transform the city’s transportation system. The Delhi EV Policy and the proposal to re-develop 540 kilometre on urban roads in Delhi are important steps in this direction. However, what is needed is a great pace and faster implementation of these strategies.

In addition, the surrounding cities of Delhi such as Noida, Gurugram and Ghaziabad also need to take some similar initiatives to create the desired impact.

The writer is executive director (Transport), WRI India. The views expressed are personal.

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