Air Quality in India: When and Where It Is Worst, and How to Read the AQI

The winter months. The UK Foreign Office describes severe air pollution as a major health hazard in India, especially during the winter months from October to February, and Canada's travel advice says it is typically at its worst in winter, when smoke haze can be extremely hazardous in cities such as Delhi. Canada adds that agricultural burning can affect air quality in the countryside too.

The national data show the same pattern. The Central Pollution Control Board, CPCB, publishes a daily air quality index for each city it monitors. We read its bulletins for the 5th, 15th and 25th of every month from October 2025 to September 2026, 36 days in all. On them, Delhi was in the Poor, Very Poor or Severe band on eight of the nine sampled days from November to January, averaging 297, and reached Severe, 427, on 15 December 2025. It was Poor on all three sampled days in February and two of three in October. From July to September, the monsoon months, it averaged 96 and was never worse than Moderate. Spring is not always clear: three of the nine sampled days from March to May were Poor as well.

On the same CPCB bulletins, from November to January:

• Delhi and its neighbours. Ghaziabad, Noida and Gurugram matched Delhi, Poor or worse on eight of the nine sampled days. Towns around the capital in Haryana and western Uttar Pradesh were often as bad: Meerut was Very Poor on five of the nine days.
• Odisha's cities. Cuttack and Bhubaneswar were Poor or worse on eight of nine days, averaging about 250, a reminder that winter smog is not only a Delhi story.
• The Golden Triangle beyond Delhi. Agra averaged 155 and was never worse than Moderate; Jaipur averaged 160 and was Poor on one sampled day.
• Kolkata and Lucknow. Mostly Moderate, with two and three Poor days respectively.
• Mumbai and the south. Mumbai, Chennai, Bengaluru, Hyderabad and Thiruvananthapuram were never worse than Moderate on any sampled day across the year.
• The hills. Srinagar and Shillong were Good or Satisfactory on every sampled winter day they reported, though they reported on fewer days.

A city's index is the average of its monitoring stations, and CPCB notes that air quality varies across a city, so a single figure is a guide to the day, not a reading for your street.

CPCB's index turns the readings for up to eight pollutants, particulate matter (PM2.5 and PM10), nitrogen dioxide, sulphur dioxide, carbon monoxide, ozone, ammonia and lead, into one number from 0 to 500. The worst pollutant on the day sets the index. The daily bulletin is issued at 4 pm and gives the average of the past 24 hours. These are the six bands and the health impacts CPCB attaches to each:

Note that India's bands are its own: an index of 150 is Moderate on CPCB's scale, so do not read it against another country's colours.

The UK Foreign Office says children, older people and those with existing medical conditions may be especially affected, and that if you are pregnant or have a respiratory or heart condition you may wish to consult a medical practitioner before you travel. CPCB's own guidance for the Very Poor and Severe bands is that people, especially those with heart disease or asthma, may consider avoiding undue exposure. The UK's TravelHealthPro lists outdoor air quality among the health risks for India.

If you have asthma or a heart or lung condition, raise the winter air at your pre-travel appointment, carry your usual medicines, and know how to reach a doctor or hospital in India.

Most travellers plan around the winter air rather than avoid the north altogether. A few things help:

• Check CPCB's bulletin, or its website, the day before an outdoor-heavy day, and keep a Poor or Very Poor day for indoor sights; our Delhi travel guide helps you plan the days.
• Keep the Delhi part of a winter trip short. Agra and Jaipur ran cleaner on the days we sampled.
• If clean air matters most, look south: Thiruvananthapuram never went beyond Moderate on the days we sampled, and our Kerala travel guide covers when to go.
• Month by month, our pages on India in November, December and January set the air beside the weather and the festivals.

The rest of the health planning, from vaccinations to insurance, is in our guide to health in India for travellers.