Winter chill ups pollution in Hyderabad

Hyderabad: This winter season is proving to be harsher than any other year. As the city battles with falling mercury, the Air Quality Index (AQI) of Hyderabad too has deteriorated drastically. As of December 23, several parts of the city including Bolarum, Patancheru and Rajendranagar had a moderate AQI (101-200), indicating that pollution in the […]

Hyderabad: This winter season is proving to be harsher than any other year. As the city battles with falling mercury, the Air Quality Index (AQI) of Hyderabad too has deteriorated drastically. As of December 23, several parts of the city including Bolarum, Patancheru and Rajendranagar had a moderate AQI (101-200), indicating that pollution in the air was dense enough to cause breathing difficulties to lung and heart patients. At the same time, Sanathnagar’s AQI at 261, was the worst in the city on Thursday.

Experts deduce that this rise in pollution levels is due to the winter. Cold temperature can trap pollutants near the ground through a process called ‘temperature inversion’. This happens as there is a layer of warm air sitting above the colder air surface, acting like a lid that traps in pollution and allergens. One can think of it as a pollutant catching blanket that covers the ground when it is winter.

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The Director of India Meteorological Department, Hyderabad, Dr K Nagaratna, points out, “The quality of air depends heavily on the weather. During the winter season, the cold air is denser and moves slower than warm air. This density means that cold air traps the pollution but also doesn’t whisk it away.”

Each year, in Hyderabad, the AQI levels start rising as the winter approaches. The quality of air is generally poor from October to March. This year, however, the pollution was less in November, possibly due to the rains caused by Cyclone Nivar.

While the toxics that floats in the air during winter is composed of several types of pollutants, including sulphur dioxide (SO2), nitrogen dioxide (NO2), PM10 and Ozone, the level of PM2.5 — which in large quantity can cause asthma or other lung-related ailments — is exceptionally high in winter. On Thursday, the PM 2.5 level was recorded at 269 in Sanathnagar. PM 2.5 has been a prominent pollutant in various other places across the city.

Also read: Night temperatures may rise in Hyderabad