Delhi's Pollution: Did Odd-Even Rule Work?

Delhi's air quality is in a severe category, and the government has decided to reintroduce the odd-even scheme to curb air pollution. The scheme will be implemented for the fourth time in Delhi, where cars can ply only on alternate days based on their registration number. The idea is to cut the number of cars on the road by roughly half, which the government hopes will bring down air quality index (AQI) levels. The scheme has shown some positive results in the past, with a study by Delhi Technological University in 2016 showing a drop in PM 2.5 and PM 1 levels during its implementation. However, the Supreme Court and experts have questioned its efficacy, stating that it has had no visible impact on improving the air quality in the city.

The odd-even scheme's efficacy is debated, with some studies showing a reduction in pollution and others showing no change

The efficacy of the odd-even scheme in Delhi has been hotly debated, with some studies showing a reduction in pollution and others showing no change. The scheme, which aims to reduce air pollution by restricting cars from plying on alternate days based on their number plates, has been implemented multiple times since 2016.

A study by the Delhi Technological University in 2016 found that when the scheme was implemented for a roughly two-week period, there was a drop in the concentration of PM 2.5 and PM 1. On average, there was a reduction of 5.73% in PM 2.5 and 4.70% in PM 1 levels. The Energy Policy Institute at the University of Chicago and Evidence for Policy Design also analysed the impact of the odd-even scheme implemented in 2016 and found a 14-16% reduction in PM2.5 levels during the hours the scheme was in force.

However, the same study found that when the scheme was reintroduced in April 2016, there was no reduction in pollution. Similarly, a study by the Environment and Climate Change think tank, Centre for Science and Environment (CSE), found that while the odd-even scheme reduced pollution in the short term, there were reasons to doubt its long-term efficacy. The study suggested that the policy could be easily gamed or undermined and might even lead to an increase in pollution as households could be encouraged to purchase old and highly polluting second cars.

The Indian Express analysed the scheme's efficacy in 2019 by comparing the Air Quality Index (AQI) levels in Delhi with those in Gurgaon, Ghaziabad, and Noida, which are in the same National Capital Region (NCR) and share similar environmental factors but did not implement the odd-even scheme. The results showed that the average AQI decreased most significantly in Delhi, where the odd-even scheme was in place. The average AQI in Delhi between October 23 and November 3, 2019, before the implementation of odd-even, was 369.5. During the odd-even scheme from November 4-15, the average AQI was 328.5, a 41-point reduction.

Despite the positive results of some studies, experts say that determining the exact impact of an individual measure on air pollution is difficult as many factors influence air quality. For example, on the first day of the odd-even scheme in 2019, strong winds were observed in the city, which would have contributed to a significant reduction in AQI.

The Supreme Court of India said there was little evidence that the odd-even scheme significantly reduced pollution in Delhi

The odd-even scheme in Delhi, implemented to reduce air pollution, has sparked debate about its effectiveness. While some argue that it has helped lower pollution levels, the Supreme Court of India has stated that there is little evidence to support this claim.

The odd-even scheme, first introduced in 2016 by the AAP government, aims to reduce the number of vehicles on the road by allowing only those with odd or even number plates to operate on alternate days. The policy has been enforced multiple times since then, with mixed results.

The Supreme Court's statement was based on a report by the court's amicus curiae, Aparajita Singh, who found that vehicular pollution contributes to only 17% of total pollution in Delhi, and that the odd-even scheme could reduce this to 13% but not lower. The court also criticised the Delhi government for not taking more effective action to combat pollution, particularly crop-residue burning in neighbouring states.

Despite the Supreme Court's stance, the Delhi government continues to defend the odd-even scheme, arguing that reduced congestion and smoother traffic flow during its implementation help to lower pollution levels. The government also highlights the success of similar schemes in other cities like London and Singapore.

However, environmentalists and experts have questioned the efficacy of the odd-even rule, calling it a knee-jerk reaction rather than a long-term solution. They argue that vehicles are not the main cause of pollution in Delhi, and that other factors like road dust, construction, industries, coal power plants, and stubble burning in neighbouring states contribute significantly to the city's air pollution.

While the odd-even scheme has shown some positive results in reducing pollution levels during its implementation, the Supreme Court of India's statement highlights the need for more comprehensive and evidence-based approaches to address the complex issue of air pollution in Delhi.

The Delhi government argues that the scheme helps reduce pollution by avoiding the build-up of ground ambient air, a contributor to PM 2.5 levels

The Delhi government has implemented the odd-even scheme several times in an attempt to reduce air pollution in the city. The policy dictates that cars with odd-numbered registration plates can only drive on odd dates and even-numbered cars on even dates. The aim is to halve the number of cars on the road, reducing congestion and improving the flow of traffic.

The Delhi government argues that the odd-even scheme helps to reduce pollution by preventing the build-up of ground ambient air, which is a significant contributor to PM 2.5 levels and, consequently, pollution. A study by the Delhi Technological University found that when the scheme was implemented for a two-week period, there was a drop in PM 2.5 and PM 1 concentrations. On average, there was a 5.73% reduction in PM 2.5 levels and a 4.70% reduction in PM 1 levels.

Further analysis of the scheme's impact on traffic revealed that during its implementation, average vehicle speeds increased by 5.4%, indicating a reduction in the number of cars on the road. As vehicle emissions are a significant contributor to Delhi's air pollution, reducing congestion and improving traffic flow can help to lower pollution levels.

The Energy Policy Institute at the University of Chicago and Evidence for Policy Design analysed the impact of the odd-even scheme implemented in 2016. They found that Delhi witnessed a 14-16% reduction in PM2.5 levels during the hours the scheme was in force. However, it is important to note that there was no reduction in pollution when the scheme was reintroduced a few months later in April 2016.

While the odd-even scheme has shown some positive results in reducing pollution, its long-term effectiveness is uncertain. Some experts argue that similar policies in other cities, such as Mexico City, have been undermined and even led to an increase in pollution as households purchased additional old and polluting vehicles.

A more sustainable approach to reducing pollution in Delhi may be through a congestion-pricing programme, where drivers are charged for using roads during peak congestion and pollution periods. This approach has been successful in cities like London and Singapore, effectively reducing car usage during these critical times.

A study by the Delhi Technological University showed a drop in PM 2.5 and PM 1 levels when the scheme was implemented for a roughly two-week period

Delhi has long struggled with poor air quality, with the city's PM2.5 levels remaining more than twice the safe standard over the past two decades. In response to this issue, the Delhi government has implemented the odd-even scheme several times, a vehicle rationing programme that allows cars with number plates ending in an odd or even digit to drive on odd or even dates, respectively. The goal of this scheme is to reduce the number of cars on the road by roughly half, thereby lowering air pollution levels.

The odd-even scheme was first introduced in Delhi in 2016 and has since been implemented three more times, including in November 2024. While the scheme has shown some positive results, its effectiveness has been debated. A study by the Delhi Technological University found that during the roughly two-week period when the scheme was in effect in November 2019, there was a noticeable drop in PM 2.5 and PM 10 levels. The average Air Quality Index (AQI) in Delhi decreased from 369.5 before the scheme to 328.5 during its implementation, a reduction of 41 points.

This reduction in pollution levels is significant, as PM 2.5 pollutants can penetrate deep into the lungs and pose serious health risks. The high levels of PM 2.5 in Delhi have led to the city being ranked as one of the most polluted in the world by the World Health Organization. The odd-even scheme, therefore, offers a potential solution to help mitigate this issue.

However, it is important to note that the impact of the odd-even scheme may be influenced by other factors, such as wind speed and temperature, which can affect the dispersion of pollutants. Additionally, the scheme has faced criticism for causing inevitable hardships, particularly for those who rely on vehicles for their livelihood, like auto-rickshaw driver Vikram Singh, who reported earning less during periods of high pollution.

Overall, while the odd-even scheme has shown some success in reducing pollution levels in Delhi, as evidenced by the Delhi Technological University study, it is just one part of a larger effort to improve air quality in the city.

A congestion-pricing programme, where drivers are charged for using roads at certain times, may be a more effective long-term solution

Delhi's air pollution is a complex issue influenced by various factors, including vehicle emissions, crop-residue burning, and atmospheric conditions. While the odd-even scheme, which restricts vehicles based on their number plates, has been implemented multiple times to reduce pollution, its effectiveness has been debated. Experts argue that while it may provide short-term relief, it is not a long-term solution.

A more sustainable approach to tackling Delhi's congestion and pollution could be a congestion-pricing programme. This involves charging drivers for using roads during specific times, typically in congested areas and peak traffic periods. The funds collected from these charges can then be utilised to improve public transportation and road infrastructure.

Reducing Congestion and Encouraging Public Transportation:

Delhi's roads are chronically congested due to the increasing number of vehicles, and its public bus fleet size is currently at a nine-year low. A congestion charge during peak hours can discourage private vehicle usage, thinning out congested streets. The revenue generated can be invested in expanding and improving Delhi's bus and metro systems, making them more attractive and accessible to commuters.

Fairness and Equity:

Unlike the odd-even scheme, congestion pricing does not restrict access based on number plates. Instead, it provides an incentive for those who can afford to pay to drive during peak hours, while also encouraging others to consider alternative modes of transportation. This approach aligns with the principles of good transport reform, ensuring people's access and mobility while managing congestion.

Successful Examples:

Cities like Singapore, London, Stockholm, and Beijing have implemented congestion pricing with positive results. Singapore, a pioneer in this approach, successfully reduced congestion and improved traffic flow. London experienced a 30% reduction in congestion within its charging zone. Stockholm witnessed increasing public support for road pricing, with approval ratings of nearly 70%. Beijing has integrated congestion pricing into its low-emission zone policy to curb air pollution.

Incremental Implementation:

Delhi can start by converting existing toll roads to fully electronic free-flow operation, utilising the National Electronic Toll Collection programme. This provides a foundation for testing charging mechanisms without barriers and implementing higher charges during congested periods. A gradual implementation approach allows for adjustments and ensures that the system is tailored to Delhi's unique context.

Addressing Criticisms and Building Public Support:

Criticisms of congestion pricing in Delhi, such as concerns about equity and the city's geographical spread, can be addressed through careful planning and communication. By ensuring basic connectivity and improving alternative modes of transportation, the government can make it easier for people to walk, cycle, or use public transport. Additionally, learning from the experiences of other cities, Delhi can focus on educating the public about the benefits of congestion pricing and gaining their support.

In conclusion, while the odd-even scheme may provide temporary relief, a well-designed congestion-pricing programme has the potential to offer a more sustainable and effective long-term solution to Delhi's congestion and pollution challenges. By reducing traffic, improving public transportation, and generating revenue for infrastructure development, such a programme can contribute to a healthier and more livable environment for Delhi's residents.

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