The odd-even scheme of the Delhi government is a traffic rationing measure under which private vehicles with registration numbers ending with an odd digit will be allowed on roads on odd dates and those with an even digit on even dates. As and when the scheme is implemented, vehicle registrations ending with odd digits like 1, 3, 5, 7, 9 would not be allowed on the roads on even dates like 2, 4, 6, 8, 10. Similarly, vehicles with registration numbers ending with an even digit - 0, 2, 4, 6, 8 - would not be allowed on the roads on days with odd number date, like 5, 7, 9, 11, 13 and 15.
Origin of Odd-even rationing
While Delhi chief minister Arvind Kejriwal used the odd-even scheme in the national capital for the first time in 2016, the concept is, however, not new.
The scheme was instituted in the US in 1979. The US used odd-even rationing when unstable conditions in Iraq and Iran led to a worldwide increase in oil prices.
The scheme was used again in 2012 after Hurricane Sandy hit the US. Gasoline became scarce, which led to fuel hoarding. License plates without numbers were considered odd.
Countries that have used odd-even scheme to curb pollution
Ahead of the 2008 Olympic Games, Beijing imposed the Odd-Even scheme. In August 2015, China imposed restrictions on factory production and car use in Beijing, forcing around five million cars to ply on alternate days for around two weeks
Odd-even rule has frequently been imposed in Paris during periods of high air pollution. On such days, public transport is free in the city.
Mexico issued a circular in 1989 that called for citywide bans, one day per week, based on odd-even number plates to fight air pollution.
In Rome, citizens were told to follow the odd-even rule in 2015.
Arvind Kejriwal-led Delhi government implemented the odd-even scheme for the first time in Delhi in 2016, 2017 and then in 2019. Every year, post-Diwali, air pollution levels in India's capital city shoot up to dangerous levels. Apart from air pollution from Diwali crackers, the crop-residue burning in the neighbouring Punjab and Haryana adds to the city's woes. On November 1, 2019, the Air Quality Index (AQI) level went as high as 700 forcing a Supreme Court-mandated panel to declare a public health emergency in the Delhi-NCR region. It banned construction activity for five days and schools were shut, too.
The odd-even scheme was one of the measures adopted by the Delhi government.
Arvind Kejriwal's scheme hailed worldwide
Kejriwal was named among the world's 50 greatest leaders by Fortune magazine in 2016 for his efforts to curb pollution in New Delhi through the scheme of allowing vehicles of odd and even numbers on alternate days on the city's roads.
"When Kejriwal unveiled a blueprint to tackle the smog in New Delhi -- called the world's most polluted city by the World Health Organization -- many were sceptical. "The uplifting result of the pilot: roads were less clogged, hourly particulate air pollution concentrations dropped by 13 per cent, and citizens could breathe deep," Fortune said.
Benefits of odd-even scheme
— Reduction in road congestion
— Slight drop in pollution levels
— These restrictions on cars have been followed up with measures to boost public transport, including more buses and increased frequency of metros.