NEW DELHI — The Delhi government announced an emergency plan Friday to curb the capital’s pollution levels, among the worst in the world, by limiting drivers to alternate days beginning next month.
From Jan. 1, residents of the city, which had been choking in thick smog in recent days, will be able to drive only every other day according to their license plate numbers — odd numbers on one day, even numbers on the other.
They also plan to shut down Delhi’s large coal-fired power plant and make Euro VI emission norms mandatory for motor vehicles from 2017.
Delhi’s chief minister said at a forum over the weekend that the alternate-day traffic schedule was an “emergency” measure and would be discontinued if a trial period proved it to be unworkable. Delhi’s police have already complained they don’t have the manpower to enforce it.
“We don’t want to cause any inconvenience to the public,” Arvind Kejriwal said.
The plan was announced after the state of Delhi’s high court issued a directive Thursday ordering the state and national governments as well as the Delhi Pollution Control Committee to devise a plan by Dec. 21 to address rising levels of air pollution.
“It seems like we are living in a gas chamber,” said the court, which is based in the capital city.
New Delhi’s air — a noxious combination of exhaust, dust, smoke from wood and dung-fired stoves, burning leaves and industrial output — surpassed Beijing’s last year as the dirtiest in the world, according to a study by the World Health Organization.
On Friday, its concentration of particulate matter — the airborne particles that enter people’s lungs and pose a major health threat — was a “hazardous” 652 at one point in the afternoon, compared with an “unhealthy” 180 in Mumbai and Hyderabad, two other major Indian cities.
Officials say they hope the measure will reduce pollution levels by 50 percent. They also plan to shut down Delhi’s large coal-fired power plant and make Euro VI emission norms mandatory for motor vehicles from 2017.
“This is being done for the interests of the citizens and the public,” Delhi state’s chief secretary, K.K. Sharma, said in a meeting with reporters. “We expect the public to cooperate.”
The capital’s most recent effort to regulate polluters — a ban on diesel vehicles older than 10 years — descended into chaos this year, with traffic jams at checkpoints and city officials arguing that enforcing the policy was impossible.
“We must move toward reforms, but we have to be practical,” said Harsh Vardhan, a physician who is India’s minister of science and technology. “Also, don’t say something you can’t implement.”
The city’s smog is always bad in winter, but it has been unusually thick in recent days, exacerbated by fireworks set off for the festival of lights, Diwali, on Nov. 11.
The air quality worsened sevenfold from the start of October to the end of November, according to a study by the Center for Science and Environment in New Delhi, which showed that 3 percent of days in October and 73 percent in November had severe air quality.
“Clearly there has been a huge increase,” said Anumita Roychowdhury, the center’s executive director for research and advocacy and head of its air pollution and clean transportation program. “These levels are several times higher than the standard. This has serious health impacts.”
She said that the new pollution-control plan would be a catalyst for drivers to think of alternative ways to commute — by car pooling, limiting their trips or by traveling on foot or by bicycle.
The capital’s last significant push for cleaner air began in the late 1990s, when the government closed small polluting factories and switched all buses and auto rickshaws from diesel to compressed natural gas. But the gains made after the switch began to decline about 2008 when the number of motor vehicles began to increase, Roychowdhury said.
The rationing of road use has been practiced in large cities in Latin America and elsewhere for more than two decades. In Beijing, motorists cannot drive in the city center one day a week. London uses “congestion pricing” — a fee on driving in the city’s core that is about $17 a day on weekdays.
But some environmental activists said implementation would be difficult in the sprawling India capital, with 16 million residents and 2 million registered motor vehicles. Although city officials said Friday that they would increase bus service and extend times for Metro service, they are still about 10,000 buses short of demand, according to Amit Bhatt, a sustainable-transportation expert in New Delhi.
“It will be very challenging,” said Bhatt, the head of transportation at the EMBARQ program in the India branch of the World Resources Institute. When a system of alternate days was launched in Bogota, Colombia, Bhatt said, many residents simply bought cheap second cars, choosing vehicles with license plates to complement their primary vehicles so that they could drive every day. Bogota eventually switched the odd-even number system to peak hours only, which has been more successful, Bhatt said.
Yet such moves do reduce the harmful particulate matter in the air, Bhatt said. To tap that benefit, his group has co-created voluntary car-free days in New Delhi and Gurgaon, a suburb. Gurgaon has voluntary car-free Tuesdays in four major corridors. On Tuesdays, particulate pollution drops sharply, Bhatt said.