A traffic police personnel wears a mask to protect himself from pollution in New Delhi. The air quality reached "hazardous" zone during Diwali in the national capital on Sunday. (File Photo: IANS)
The air quality index (AQI) was 763, the highest, at the National Malaria Institute in Dwarka (West Delhi). It was 407 at the ITI Jahangirpuri (North Delhi) and 313 at Shrinivaspuri. (File Photo: IANS)
Vehicles ply amidst light smog in New Delhi. The national capital's air quality dropped to the season's worst on the morning after the festival of Diwali, but the situation was still better than the last three years, according to government agencies. (AP Photo/Manish Swarup)
A man paddles a home-made boat across Yamuna river on a smoggy morning in New Delhi. Residents woke up to a pall of grey left behind by acrid smoke from fireworks that remained trapped in the city's cool air. REUTERS/Adnan Abidi
A man wearing a mask runs past the India Gate on a smoggy morning in New Delhi. The Supreme Court had ordered residents to only use safe and environmentally friendly fireworks for a maximum of two hours, and only in designated areas such as parks, but the law was violated in several parts of the city, residents said. REUTERS/Adnan Abidi
A man covers his face with a handkerchief as he walks to work early Monday morning. Due to emission from firecrackers and stubble burning in adjoining areas of the NCR, the pollution situation is expected to worsen in the coming weeks. (AP Photo/Manish Swarup)
Mid-October to November is considered critical days for Delhi's air quality due to stubble burning in neighbouring states and emissions from firecrackers during Diwali. (AP Photo/Manish Swarup)
A thin layer of haze is already hanging over Delhi. (File Photo: Sunil Majumdar/IANS)
A man rides a cycle past the India Gate on a smoggy morning in New Delhi. Delhi will restrict the use of private vehicles on the capital's roads under an "odd-even" scheme based on vehicle number plates from next week. REUTERS/Adnan Abidi
The levels have remained above 300 since early Monday morning, or "very poor", which can cause respiratory illness after prolonged exposure. REUTERS/Adnan Abidi