India’s capital banned fuel sales to aging vehicles on Tuesday as authorities try to tackle the sprawling megacity’s hazardous air pollution.

The city is regularly ranked one of the most polluted capitals globally with acrid smog blanketing its skyline every winter.

At the peak of the smog, levels of PM2.5 pollutants—dangerous cancer-causing microparticles small enough to enter the bloodstream through the lungs—surge to more than 60 times the World Health Organization’s recommended daily maximum.

Petrol cars older than 15 years, and diesel vehicles older than 10, were already banned from operating on New Delhi’s roads by a 2018 Supreme Court ruling.

But millions flout the rules.