Pollution levels shoot up further in Mumbai, AQI at 269

A day after air pollution levels touched a season high of 245 on the air quality index (AQI), pollution levels shot up further on Tuesday in Mumbai, peaking at 280 in the morning, and then dropping slightly to settle at an index value of 269 by evening

A day after air pollution levels touched a season high of 245 on the air quality index (AQI), pollution levels shot up further on Tuesday, peaking at 280 in the morning, and then dropping slightly to settle at an index value of 269 by evening. An AQI of 269 falls in the “poor” category, which, as per the Central Pollution Control Board, can cause “breathing discomfort to most people on prolonged exposure.”

A thick layer of haze over the Arabian sea at Bandra, Mumbai. An AQI of 269 falls in the “poor” category, which, as per the Central Pollution Control Board, can cause “breathing discomfort to most people on prolonged exposure.” (HT PHOTO)

This is as per data from the System of Air Quality and Weather Forecasting And Research (SAFAR) network of 10 monitoring locations across the city.

Gufran Beig, meteorologist and project director, SAFAR, explained that a buildup of moisture in the city has allowed the air to retain a larger quantum of particulate matter pollutants, like PM2.5 and PM10, pushing up the AQI in almost all monitoring locations.

According to IQ Air, a Swiss air quality technology and monitoring company, Mumbai’s air quality on Tuesday evening made it the seventh most polluted city across major cities globally. Delhi was the second worst, while Kolkata came in at number 10. IQ Air follows more stringent air quality guidelines laid down by the United States of America’s Environmental Protection Agency (EPA), as per which the AQI of all three Indian cities fell in the “unhealthy” category.

Experts attributed the spike in pollution — particularly particulate matter (PM) — over the past two days to an incursion of moisture after the formation of a low-pressure area in the Arabian Sea off Maharashtra’s coast. Air quality had also dipped to the “poor” category this month on November 5, a day after Diwali, when the AQI touched 215. However, the overall AQI as presented by SAFAR is an average of its city-wide network, which shows significant geographic variation.

Colaba continued to register the city’s most polluted air with an AQI of 370 on Tuesday evening (up from 345 on Monday). This was in the “very poor” category, which, as per the CPCB can cause “respiratory illness on prolonged exposure.” Other locations with “very poor” air on Tuesday included Mazagaon at 331 (up from 325 on Monday) and Malad with an index value of 327 (up from 306 on Monday). “Very poor” air persisted in Bandra-Kurla Complex which recorded an AQI of 311 (314 on Monday).

Only Andheri registered a significant improvement in air quality, with a "moderate” AQI of 183 (down from a “poor” reading of 259 on Monday). Meanwhile Chembur (183), Borivli (159), Worli (142), Bhandup (125) and Navi Mumbai (183) all recorded “moderate” air on Tuesday, with slight deteriorations from Monday. “Moderate” air quality can cause “breathing discomfort to people with lung disease such as asthma, and discomfort to people with heart disease, children and older adults,” as per the CPCB’s health advisory.

“Because of the low-pressure area, moisture laden winds have started blowing over the city, pushing up the humidity levels. When this happens, the air becomes heavier and is able to hold pollutants, especially PM2.5 and PM10, to a greater capacity. This is why haze has accumulated over some parts of the city. Locations with higher AQI are very likely also more humid, such as in south Mumbai. At the moment, winds are not strong enough to disperse this haze but there may be some relief tomorrow due to rains,” Beig said, pointing out that parts of the South Konkan and adjacent area, including Sindhudurg, Ratnagiri coast have already begun receiving thunderstorms as of Tuesday evening.

Rising humidity levels have also coincided with an uptick in temperature over the past week, with Tuesday’s daytime maximum settling at 35.7 degrees Celsius (two degrees above normal), up from 35.2 degrees Celsius a day prior. This was after maximum daytime temperature dropped to a monthly low of 32.8 degrees Celsius on November 7.

Mornings in the city have also been getting warmer, with Tuesday’s minimum nighttime temperature settling at 25.4 degrees Celsius — four degrees more than normal — up from 24.4 degrees Celsius a day prior. On November 11, the minimum temperature was 19.8 degrees Celsius. Both maximum and minimum temperatures are expected to remain above normal till Friday, as per IMD’s seven-day forecast for Mumbai.

“We were expecting it to rain in Mumbai on Tuesday, but the influence of the low-pressure area is being felt more in south Maharashtra. Northern Raigad, Mumbai and parts of interior Thane will get rains either Tuesday night or Wednesday. There is a likelihood of thunderstorms continuing till early Friday,” said a meteorologist with the IMD’s regional forecasting centre in Mumbai.

The highest daytime maximum temperature recorded this month in Mumbai was on November 14, when the mercury touched 36.6 degrees Celsius. Last year, the highest temperature recorded in November was 36 degrees Celsius (on November 15 and 18).