As Delhi Readies for Odd-Even Comeback, Will Scheme Improve Air Quality? Data Says the Opposite

Delhi chief minister Arvind Kejriwal on Friday announced the return of the odd-even car rationing scheme from November 4 to 15 in the national capital to curb air pollution.

The scheme was implemented for the first time between January 1 and January 15 in 2016 after alarming levels of PM2.5 (Particulate matter) and PM10 concentration were recorded in Delhi's air, making it one of the most polluted cities on Earth.

The plan was re-introduced for 15 days in April, 2016 and five days in November, 2017. Under the programme, cars with their license plate number ending in an odd or even number are allowed on the roads on alternate days, with special exceptions for women, VIPs, etc.

While the Delhi government hailed it as a huge success, several studies have said that the programme had very little or no impact in improving the air quality of the national capital.

According to a analysis of air quality data for the second and third-round of the scheme (April, 2016 and November, 2017) accessed from Berkeley Earth, a California based non-profit, shows that air quality in Delhi, in fact, deteriorated during the 'odd-even' program.

For instance, the average concentration of PM2.5 in Delhi during the second-run of 'odd-even' between April 1 and April 15, 2016 was 116 µg/m³ whereas it was 82 µg/m³ and 92 µg/m³ during the same period in 2017 and 2018, respectively when there was no special pollution control plan in place, the data suggested.

Similarly, during the third-round from November 13 to November 17, 2017, average PM2.5 stood at 218 µg/m³. In contrast, it was 171 µg/m³ in 2016 and 140 µg/m³ in 2018 without any traffic restrictions.

As Berkeley Earth has air pollution data only from March 2016 onwards, similar analysis could not be done for the first-round of 'odd-even' in January, 2016.

However, a 2017 study by professors/scientists from IIT Delhi, IIT Kanpur and Indian Institute of Tropical Meteorology, Pune concluded that during January, 2016 run of the scheme PM 2.5 concentration in Delhi saw a decline of only 2-3 per cent.

“It can be concluded that restricting traffic volume alone cannot control the PM 2.5 concentration over Delhi, where there are multiple other sources of contributing towards making the city’s air dirty,” the study observed.

The latest attempt to reintroduce the 'odd-even' has come in the wake of concerns over poor air quality in the capital during November due to crop burning in Haryana, Punjab and bursting of crackers during Diwali celebrations.

CM Kejriwal, however, said in his press briefing that the restrictions “will not be implemented in case the air pollution level does not cross the danger mark.”

Meanwhile, according to a recent report by AirVisual/Greenpeace, Delhi is the 11th most polluted city in the world with an average PM2.5 concentration of 113.5 µg/m³ during 2018, which is over 10 times more than what the World Health Organisation considers as safe. In fact, 22 of the most 30 most polluted cities on Earth are in India.

Additionally, respiratory diseases emerged as the third-leading cause of death in India, accounting for 9.2 per cent or 1.29 lakh of the total 14.11 lakh medically certified deaths in 2017, as per latest data released by the Office of the Registrar General of India. In Delhi, of the total 82,608 medically certified deaths, respiratory diseases were the cause of death in at least 7,500 of them.