Authorities in India’s capital Delhi rolled out strict measures on Wednesday in an attempt to curb pollution, including a ban on vehicles not compliant with latest emission control norms and regulating attendance in private and government offices.

The air quality index in the Delhi region, home to 30 million people, has been in the “severe” category for the past few days, often crossing the 450-mark. In addition, shallow fog in parts of the city worsened visibility that affected flights and trains.

This prompted the Commission for Air Quality Management to invoke stage four, the highest level, of the graded response action plan for Delhi and surrounding areas on Saturday.

The curbs ban the entry of older diesel trucks into the city, suspend construction, including on public projects, and impose hybrid schooling.

Kapil Mishra, a minister in the local government, announced on Wednesday that all private and government offices in the city would operate with 50% attendance, with the remainder working from home, apart from some exceptions.

Additionally, all registered construction workers, many of them earning daily wages, would be given compensation of 10,000 rupees ($110) because of the ban, Mishra said at a press conference in Delhi.

India’s Environment Minister Bhupender Yadav directed authorities to ensure construction and demolition activities in Delhi and its suburbs were permitted only if proper waste handling infrastructure was available.

To better regulate traffic, the minister directed the removal of illegal encroachments and creation of corridors for smooth movement during peak traffic hours.

On Tuesday, the government enforced strict anti-pollution measures for vehicles in the city, banning vehicles that are not compliant with the latest emission control standards.

“Our government is committed to providing clean air in Delhi. We will take strict steps to ensure this in the coming days,” Delhi’s Environment Minister Manjinder Singh Sirsa said late on Tuesday.

Pollution is an annual winter problem in Delhi and its suburbs, when cold, dense air traps emissions from vehicles, construction sites and crop burning in neighbouring states, pushing pollution levels to among the highest in the world and exposing residents to severe respiratory risks.

The area gets covered in a thick layer of smog with the AQI touching levels in the high 450s. Readings below 50 are considered good.