As the city's air quality continued to languish in the ‘very poor category for the seventh consecutive day, the Central for Science and Environment (CSE) on Wednesday claimed that the mobility crisis is behind the pollution in Delhi. This means vehicular emission is the top contributor to Delhi's pollution during winter season--more than stubble burning, road dust or bursting of firecrackers -- with over 50 per cent of pollution from local sources linked to the city's fragmented transportation system. An estimated 1.1 million vehicles enter and exit Delhi daily, further worsening the air quality.  The traffic caused by this vehicle influx intensifies pollution, particularly nitrogen oxides (NOx), which account for 81 per cent of NOx pollution in Delhi.

 “Even after implementing the largest ever CNG programme for the public transport and local commercial transport, phasing out of 10-year-old diesel and 15-year-old petrol vehicles, restrictions on entry of non-destined trucks, introduction of Bharat Stage 6 emissions standards, and onset of the fleet electrification, vehicles are still the key polluter due to the growing mobility crisis", according to a data presented by the CSE.

According to data presented by the CSE, local pollution sources in Delhi account for 30.34 per cent of the city's air pollution (50.1 per cent of which is contributed through transportation), while 34.97 per cent originates from the neighbouring NCR districts and 27.94 per cent from other areas. Stubble burning contributes only 8.19 per cent to Delhi's pollution levels.

As per data, even though the long term PM2.5 levels have shown a downward trend, since 2022 the annual levels have remained and even shown an upward trend. The annual PM2.5 levels show an improvement of 7 per cent in 2023 when compared to the 2019 levels. Delhi requires another 60 per cent reduction to meet the National Ambient Air Quality Standards for PM2.5. Similar trend is reflected in the winter pollution, even though the winter peaks have declined the average level for the winter months have stayed elevated and also seen an increase. These data points are based on the CSE's analysis from different bodies, including the IITM, TERI-ARAI, CPCB's real-time air quality data and traffic data from Google map, among others.

Currently, public transport in Delhi is costly for the users, with around 50 per cent of public transport users spending 18 per cent of their annual income on transit, compared to 12 per cent for private vehicle owners. The CSE highlighted the need for an integrated transportation system focused on improving public transport to address these issues.

Despite the demand, Delhi's public transport system remains inadequate. Although the city has added buses, reaching 7,683 buses (including 1,970 electric buses) by July 2024, it still falls short of the Supreme Court's 1998 directive to deploy 10,000 buses.  Currently, Delhi operates about 45 buses per lakh population, below the Ministry of Housing and Urban Affairs' benchmark of 60 buses per lakh population. Bus breakdowns are also on the rise, with cases increasing from 781 in 2018-19 to 1,259 in 2022-23. Bus ridership, despite increasing, remains 25 per cent lower than pre-pandemic levels for DTC buses and seven per cent lower for cluster buses. Meanwhile, metro ridership has shown some recovery, though counting methods were revised in 2019-20 to reflect the number of corridors used instead of unique trips by commuters.

Data shows that during peak traffic hours (5 PM - 9 PM), when average traffic speed drops to 15 km/h, NO2 levels are 2.3 times higher than noon levels (12 PM - 4 PM) when traffic speed averages 21 km/h. These congestion-related emissions worsen air quality, especially during winter when inversion layers trap pollutants close to the ground. To achieve its clean air targets, Delhi must reduce emissions by 62 per cent. However, urban sprawl has increased travel distances, while public transport usage continues to decline, with a 20 per cent drop in bus travel over the past decade.

 The high cost of congestion affects Delhi's workforce, with unskilled workers losing an estimated Rs 7,500 to Rs 20,100 annually and skilled workers Rs 9,900 to Rs 26,600 due to traffic delays, amounting to 4 to 12 per cent of their income.

“The PM2.5 winter peak has reduced by almost 35 per cent in 2023-24 compared to the 2019-20 level but the average PM2.5 concentration has almost stagnated and is the highest in the last 5 years. In the last five years, the winter average of PM2.5 concentration was the highest in 2023-24 at 189 µg/m3. There is a 9 per cent increase in the winter average concentration in 2023-24 compared to 2019-20. This upward trend needs immediate action. This reflects elevated levels of pollution and high impact of atmospheric conditions.

“The cost of congestion extends beyond delays to include loss of productivity and fuels. Sparse indicative assessments are available for Delhi.Yearly fuel waste cost due to congestion was estimated by the University of Leeds at USD 1.6 million in 2010 in in 2013. IIT Madras projected in 2015 that by 2025, USD12,003 million, and by 2030, USD 14,658 million will be the cost of congestion in Delhi, which includes productivity loss, air pollution loss and damage cost’, it said.