A thick haze of polluted air hung over India’s capital Tuesday, with authorities trying to tackle the problem by sprinkling water to settle dust and banning some building work.

The air quality index exceeded 400, about eight times the recommended maximum, according to the state-run Central Pollution Control Board.

Favourable winds had briefly halved that measure of pollutants, but winds blowing from the northwest carried emissions from burning crops in Punjab and Haryana states to New Delhi, leading to high levels of pollution, according to the government’s air quality monitoring system Safar.

India Toxic Air
New Delhi is enveloped in thick smog (Manish Swarup/AP)

Air pollution in northern India peaks in the winter due to smoke from agricultural fires. Farmers say they are unfairly criticised and have no choice but to burn stubble to prepare their fields for the next crop.

Stringent pollution controls have been imposed, such as sprinkling water from high-rise buildings and banning some building work to settle or avoid dust, but the worsening air quality in Delhi has remained persistent.

Restrictions on private vehicles meant to reduce emissions were relaxed Monday and Tuesday for 550th birth anniversary celebrations of Guru Nanak, the founder of the Sikh religion.

The pollution crisis affecting 20 million residents is also piling public pressure on the government to tackle the root causes of the persistent haze.

Doctors in the capital say many of their patients these days are complaining of ailments that stem from the filthy air they breathe.

New Delhi’s chief minister Arvind Kejriwal has been making fervent appeals on Twitter and through newspaper advertisements, asking residents to do their bit to tackle the pollution problem.

World Health Organisation data released last year showed India had the world’s 10 most polluted cities.