Rising temperature & wind disperse air pollutants in Kolkata – Times of India

KOLKATA: Citizens may heave a sigh of relief with the improvement in air quality on Monday, with wind velocity gaining momentum and temperature rising, dispersing pollutants in the air at a faster rate. While all stations showed ‘satisfactory’ (AQI: 51-100) air quality, sometimes it remained marginally above the ‘moderate’ (AQI: 101-200) threshold.
Environment and health experts said the improvement in air quality may reduce health hazards as thousands of people have hit the road to soak in the festive spirit.
On Monday, reverse wind from the south started sweeping away the particulate matter very steadily, changing the prevailing colour code to light green (satisfactory) from red (very poor).

The city’s air quality had been reeling under the stress of pollutants throughout the month of December. Even the air quality monitoring station at Ghusuri in Howrah, had in the last few days consistently showed ‘severe’ (AQI: 401-500) air quality – the worst air quality any place can have.
Stations like Victoria, Ballygunge, and Javadpur kept showing poor air quality. “The temperature rose in the last few days, leaving the earth’s surface warmer compared to early or mid-December days. So, pollutants tend to go up in the atmosphere. Besides, wind velocity also gained momentum.
This phenomenon is known as the ventilation coefficient, which indicates the ability of the atmosphere to dilute and disperse the pollutants over a region” said PCB chairman, Kalyan Rudra.
Infusion of moisture from a high-pressure zone above Bay of Bengal has pushed the mercury up in south Bengal. It may start dropping from Wednesday as the high-pressure zone melts away. “Moisture from the sea has led to morning fog,” said a Met official.