Air quality slips to ‘poor’, ‘very poor’ as cold weather grips Kolkata
Telegraph | 8 January 2026
Air quality deteriorated further on Wednesday as cold weather continued to grip the city, with most monitoring stations reporting “poor” or “very poor” air through the day.
Of the seven air quality monitoring stations in Calcutta, one reported “very poor”, five reported “poor” and one recorded “moderate” air quality at noon. By 5pm, conditions had worsened: two stations — Ballygunge and Jadavpur — slipped into the “very poor” category, four were “poor”, and one remained “moderate”.
Doctors have cautioned residents against outdoor activities such as running, jogging or playing sports, warning that prolonged exposure to polluted air could affect respiratory health.
Environment scientists said the deterioration was likely due to a combination factors. “It is difficult to pinpoint one reason for the dip in air quality on Wednesday. Generally, air quality worsens when there is a spike in activities that trigger pollution. Construction work and waste burning are among the possible causes,” said a scientist with the state pollution control board (PCB).
On Wednesday, people lit numerous small fires across the city to keep warm.
The PCB scientist said the accumulated pollutant load also played a role. “Because of the low temperature, pollutants remain trapped in the lower atmosphere. When activities lead to a sudden increase in pollutants, air quality monitoring stations register a further drop,” the scientist said.
At noon, Jadavpur reported “very poor” air quality. Ballygunge, Fort William, Rabindra Bharati University (BT Road campus), Victoria Memorial and Rabindra Sarobar recorded “poor” air, while Bidhannagar was the only station in the “moderate” category. By evening, Ballygunge and Jadavpur were both in the “very poor” range, Fort William, Rabindra Bharati University (BT Road campus), Victoria Memorial and Rabindra Sarobar remained “poor”, and Bidhannagar continued to report “moderate” air quality.
According to the National Air Quality Index (AQI) of the central PCB, “very poor” air can cause respiratory illness on prolonged exposure, while “poor” air can lead to breathing discomfort for most people. Even “moderate” air — the best category recorded in the city on Wednesday — can cause breathing discomfort for people with lung ailments, asthma or heart disease.
“Moderate” air quality is already two notches below the ideal “good” category, followed by “poor”, “very poor” and “severe”.
Experts said winter conditions are a key reason behind the decline in air quality. Lower temperatures and reduced wind speeds prevent pollutants from dispersing.
Most pollutants are released in other seasons as well. “But in summer, warm air rises and carries pollutants upward, and during the monsoon, rain helps wash them out. In winter, cold air does not rise as quickly, so pollutants remain trapped in the lower atmosphere — the air that we breathe,” a scientist said.