After 15 days of ‘poor’ and ‘very poor’ air quality, pollution levels in the city improved marginally on Friday. Pollution was under the ‘moderate’ category and weather bureau officials attributed the improvement to the increase in intensity of sea breeze on Friday evening which led to dispersal of pollutants.
System of Air Quality Weather Forecasting and Research (SAFAR), Mumbai reported that the air quality index (AQI) was 205 during the day, which fell under the ‘poor’ category that dropped to 199 (moderate) by the evening. SAFAR predicted a ‘poor’ AQI of 201 for Saturday.
An AQI between 101 and 200 is considered ‘moderate’ and 201 and 300 is ‘poor’. Levels between 301 and 400 are ‘very poor’, which means people with heart or lung disease, older adults and children should reduce prolonged or heavy exertion.
On Wednesday, Mumbai recorded high pollution levels with an AQI of 304, which fell under the ‘very poor’ category for the first time since the day after Diwali, owing to poor wind speed. On Thursday, a marginal rise in wind speed led to a drop in pollution as an AQI of 286 (poor) was recorded.
“Between Tuesday and Wednesday, wind speed over the city dropped to 0-1 knots per hour, which led to zero dispersion of pollutants.Instead, they were trapped closer to the surface,” said Biswajit Mukhopadhyay, additional director general, India Meteorological Department (IMD). “Subsequently, the wind pattern changed to westerly and north-westerly (sea breeze). Wind speed increased to 3-4 knots per hour, that helped disperse pollutants faster.”
He said the city could expect similar weather conditions in the coming days. “During the night, warm winds from the east had led to a rise in overnight temperatures,” said Mukhopadhyay.
On Friday, Bandra Kurla Complex was the most polluted spot in the city that recorded an AQI of 329 (very poor). Only two locations, Andheri and Navi Mumbai, recorded ‘poor’ air quality. The remaining locations fell under the ‘moderate’ category. Bhandup recorded the cleanest air in the city on Friday.
Meanwhile, day temperatures at south Mumbai and the suburbs were a degree Celsius above normal, while night temperatures were closer to normal levels.