Haze in Chennai; pollution travels from Delhi?

After New Delhi, it was the turn of residents of this metropolis to wake up to hazy skies on Monday. Though independent weather bloggers attributed the hazy skies to polluted air travelling from north India through the East Coast, the Indian Meteorological Department (IMD) dismissed the suggestion categorically.

The quality of air in Chennai and other parts of Tamil Nadu plummeting to “unhealthy” levels since Sunday also somewhat bolstered the claims of the weather bloggers. The AQI in Chennai, which was below 50 last week, stood at 191 on Monday, according to data released by the Air Quality Management station in Alandur here set up by the Central Pollution Control Board (CPCB).

Ideally, the AQI (particulate matter 2.5) should be below 50, the quality of air is considered moderate if it is anywhere between 51 to 100. It is considered unhealthy for sensitive groups between 101 to 150 and unhealthy for everyone if it is between 151 to 200. While the AQI in Chennai was 191, it was over 500 in New Delhi and other North Indian cities.

What caused such a drastic fall in the AQI which was moderate last week? Independent weather bloggers, who have earned good reputation by rightly predicting rains and cyclones in the past, feel polluted air which is choking New Delhi and other parts of North India is travelling towards the East coast of India including Chennai.

“The satellite images show that winds are moving from North India to the East Coast. The pollution is not coming only from Delhi but from various parts of North India. Surely, the pollution levels have moved to unhealthy levels in Chennai though not dangerous like Delhi,” weather blogger Pradeep John, who runs Tamil Nadu Weatherman page on Facebook, told DH.

However, IMD, India’s official weatherman, said there was no connection between the hazy skies in Chennai and the hazardous pollution being witnessed in North India. “There is no relation between pollution in Delhi and what we see here. The haze in Chennai skies is due to the smog and there is no wind circulation though there is inflow of cold air. Polluted air traveling all the way from Delhi to Chennai is not possible,” N Puviyarasan, Director of Regional Meteorological Centre, Chennai, said.

John also warned that AQI levels may cross 200 from Tuesday and might go beyond 220 or 230 in the coming days. “This will be the pattern for next four days in Chennai. What we are seeing today in Chennai is clearly smog and not fog. There is no doubt about it,” he said.

Echoing John, another weather blogger K Srikanth, one of the prime movers behind Chennai Rains Twitter handle, which has more than 1 lakh followers, said: “Such haze has never been witnessed in Chennai. The haze continued for the whole day and I have never seen AQI going beyond the normal limits for a full 24 hours in the past in Chennai.”