This is the most polluted city in the world. And no, it's not Delhi

Residents have complained that the pollution caused by industrial smog, traffic congestion and coal-powered plants was affecting their lives and health.

Indonesian capital Jakarta has been the world's most polluted city on four days this week, according to air quality monitor IQAir, as authorities fail to grapple with a spike in toxic smog.

Air pollution is estimated to contribute to seven million premature deaths every year globally and is considered by the United Nations to be the single biggest environmental health risk.

Jakarta and its surroundings form a megalopolis of about 30 million people that has outpaced other heavily polluted cities including Riyadh, Doha and Lahore during the week for its concentration of tiny particles known as PM2.5.

It has topped Swiss company IQAir's live ranking of pollution data -- which only tracks major cities -- at least once every day since Monday, according to the company's data.

Jakarta has regularly recorded "unhealthy" levels of PM2.5, which can penetrate airways to cause respiratory problems, many times the World Health Organization's recommended levels.

President Joko Widodo told reporters Monday he plans to tackle pollution levels by reducing "Jakarta's burden" as the country prepares to move its capital to Nusantara on Borneo island next year.

He also said a planned metro train network across Jakarta "must be finished" to reduce pollution.

Residents have complained that the pollution caused by industrial smog, traffic congestion and coal-powered plants was affecting their lives and health.

"I have to wear a mask all the time. Both my body and my face are suffering," Anggy Violita, a 32-year-old officer worker in Jakarta, told AFP.

"Last week my entire family was sick for a week and the doctor told me I should stay indoors," the mother-of-two said.

A court ruled in favour of a lawsuit filed by activists and citizens against the government in 2021, ordering Widodo to clean up the city's notorious air pollution and ruling he and other top officials had been negligent in protecting residents.

Indonesia has pledged to stop building new coal-fired power plants from 2023 and to be carbon neutral by 2050.

But despite an outcry from activists, the government is expanding the enormous Suralaya coal plant on Java island, one of the biggest in Southeast Asia.

According to Greenpeace Indonesia, 10 coal-fired power plants are operating within a 100-kilometre (62 miles) radius of the capital.