BKC has poor AQI at 292, Kandivali best at 77

The overall AQI levels in Mumbai were moderate at 181 on Friday but the city was covered in a blanket of smog in several parts. While scientists attributed the current spike in AQI to the winter, wind reversal will play a huge role in changing AQI patterns in the coming days

MUMBAI: The city continues to breathe bad air as the Air Quality Index (AQI) fell into the ‘poor’ category across seven prime locations. Data from the Central Pollution Control Board (CPCB) showed that out of 14 locations, seven were in the poor category; six were in moderate and only one location recorded an AQI below 100.

Mumbai, India - Dec. 11, 2023:General view of Bandra Kurla Complex (BKC), in Mumbai, India, on Monday, December 11, 2023. (Photo by Raju Shinde/ Hindustan Times) (Hindustan Times)

The overall AQI levels in Mumbai were moderate at 181 on Friday but the city was covered in a blanket of smog in several parts. While scientists attributed the current spike in AQI to the winter, wind reversal will play a huge role in changing AQI patterns in the coming days.

Bandra-Kurla Complex, where the AQI reached 292, fell in the poor category followed by Chembur at 264, Malad West at 249, Kherwadi at 247, Shivaji Nagar at 236, Colaba at 220 and Borivali East at 202. The locations in the moderate category were Byculla at 196, Chakala in Andheri East at 194, Ghatkopar at 170, Bhandup West at 160 and Mulund West at 120. Kandivali, at 77, was the only area which recorded an AQI level below 100.

Gufran Beig, founder of NGO SAFAR (System of Air Quality and Weather Forecasting and Research) told HT, “The point is that the temperature in different parts of Mumbai is different. There is a lot of variability of temperature, which is a specific feature of Mumbai.”

Beig said that when the temperature was low in some places, there was more of a mist/foggy condition in those pockets. “Then there are places where the temperature is warmer,” he said. “Hotspot regions are more prominent in Mumbai, which does not have uniform weather. That is the reason we see this happening, as winter isn’t uniform in Mumbai.”

When asked about the smog in some pockets, Beig elaborated that it was mainly because those areas had cooler temperatures. “The atmospheric boundary layer comes down when the temperature is low and a lot of moisture is generated due to high levels of humidity; because of this, locally generated pollution gets trapped and doesn’t allow particulate matter to disperse,” he said. “Mumbai is a city where the temperature of a surface varies significantly from one location to another, and this always leads to a variation in inversion layer called the atmospheric boundary layer.”

According to the Indian Meteorological Department (IMD) forecast, a dip in temperature is expected by one or two degrees on January 2 and 3. Sunil Kamble, director, IMD, told HT that the maximum temperature in Mumbai would remain in the range of 34 degrees C but the minimum would go down to 18 or 19 degrees C.

“When there are westerly calm winds in Mumbai, pollution remains for a longer time,” he said. “But after 2 pm, there is a sea breeze and all the particulate matter gets dispersed by 10 pm. Again, at 10 pm, the wind pattern changes from westerly to easterly and again till 11 am, the suspended particles remain in the atmosphere.” The particulate matter in Mumbai remains suspended mostly from 11 pm until 12 noon.