Chennai air pollution: Air quality remains ‘moderate’ during Diwali – The Indian Express

Chennai News

Chennai remained under the cover of toxic smog late Thursday as people continued to burst firecrackers beyond the stipulated time allocated by the state government.

The air quality dropped to ‘hazardous’ levels on Thursday evening when a thick blanket of smog enveloped the city taking the pollution to 446 on the Air Quality Index (AQI) at 9:30 pm, according to data from the Central Pollution Control Board (CPCB). The city recorded an average AQI of around 154 through the day and remained in the ‘moderate’ level.

Continuing its upward trend, the city’s air quality index increased at around 8 pm on Thursday as low temperature and wind speed allowed the accumulation of pollutants.

There are seven Continuous Ambient Air Quality Monitoring Stations in the city, and an analysis of data during the evening on Thursday showed that the AQI at all the seven stations increased drastically from 7 pm onwards.

Arumbakkam station recorded an increase in AQI from 141 at 5 pm to 212 as of Friday 8 am. Perungudi recorded an increase from 152 at 8 pm to 219 as of Friday 8 am. AQI in the 100-200 range is “Moderate,” while AQI between 201 and 300 is “poor”.

N Puviarasan, Director of Area Cyclone Warning Centre at Regional Meteorological Centre, said, that there were two main reasons that can be attributed to the increase in pollution and smog on Thursday. “One, there was no wind in the second half of the day. As people continued to bust crackers in the evening, in the absence of wind, these pollutants will not disperse easily. As a result, air quality will dip under hazy conditions. Two, due to high humidity levels, pollutants get absorbed by moisture in the air.”

The north-western winds were visible late at night, after which the air quality became better, Puviarasan said. “Due to the winds late at night, the pollution dispersed and the sky was clear on Friday morning.”

The Tamil Nadu government had issued an advisory allowing the bursting of only green crackers during two fixed time windows—between 6 am to 7 am and again between 7 pm to 8 pm—on Diwali. However, many defied the timing and burst crackers after the stipulated hours.

Speaking about the weather conditions for the next few days, Puviarasan said that the pollution levels will likely reduce in the next 2-3 days as the sky will be clear since people would stop bursting crackers.