Authorities in India's capital and surrounding areas handed out fines to the owners of thousands of vehicles and construction sites for infringing pollution rules, in a bid to counter a slump in air quality during the last three weeks.
New Delhi is the world's most polluted major city, Swiss group IQAir said in its live rankings.
Almost 60,000 vehicles and more than 7,500 building sites were fined, officials said, as the Central Pollution Control Board (CPCB) rated Monday's conditions 'very poor', with a score of 373 on its index that rates levels from zero to 50 as 'good'.
As many as 54,000 of the vehicles lacked a pollution under control (PUC) certificate, showing permissible levels of emissions, the Commission for Air Quality Management said, adding that almost 3,900 more were impounded as 'overaged'.
Environmental compensation payments have been ordered for 597 sites, while 56 have been told to close.
New Delhi battles intense pollution every winter as cold air traps emissions, dust, and smoke from farm fires in the adjoining farming states of Punjab and Haryana, forcing frequent school closures and construction curbs in response.
Air quality in the region is expected to stay 'very poor' until Wednesday, the earth sciences ministry said, and is likely to range from 'very poor' to 'severe' for the subsequent six days.
The CPCB says a rating of severe, in the range of 401 and 500 on its index, affects the healthy and can have serious effects on those already suffering disease.
IQAir has rated New Delhi the world's most polluted capital for four years in a row, but poor air quality is a common winter problem across South Asia.
Rising pollution can cut a South Asian's life expectancy by more than five years, the University of Chicago's Energy Policy Institute (EPIC) said in its Air Quality Life Index last year.
Pakistan's second largest city of Lahore, which IQAir rated the world's second most polluted on Monday, has also shut primary schools for a week and urged people to stay indoors amid unprecedented pollution.
On Sunday, the provincial government said it planned talks with India to resolve the problem, blaming deteriorating air quality on pollution wafted in from its neighbour.