With the decline in temperature, the Air-Quality Index (AQI) of Mumbai too deteriorated, as the city recorded AQI worse than Delhi on Sunday. Mumbai’s overall AQI in the System of Air Quality and Weather Forecast and Research (SAFAR) dashboard showed 290, which is categorised as ‘poor’. Meanwhile, Delhi’s AQI on Sunday showed 193, which is categorised as ‘moderate’. Besides this, several pockets of Mumbai continued to record even poorer AQI. Bandra-Kurla Complex (BKC) recorded the worst AQI at 354, followed by 331 in Chembur and 307 in Andheri. Colaba recorded AQI of 286, followed by 235 in Mazagaon, 180 in Bhandup and 152 in Malad. Both, Borivali and Worli recorded AQI of 111, and Navi Mumbai’s readings showed 353. Earlier, last Friday (January 13), Mumbai recorded moderate AQI of below 150. Throughout the first week of December, Mumbai’s AQI consistently hovered between ‘poor’ and ‘very poor’, but it improved slightly during mid-December. Gufran Beig, senior scientist and project director of SAFAR stated that the quality of AQI is being reversed every 3 weeks, owing to a reversal of wind direction. “Being an island city, Mumbai's AQI is determined by winds blowing from the sea. Usually, reversal in wind direction would take place every 4-5 days. This year, however, we have seen the same occurring after a gap of 15 days. During this period, surface winds blow at a slow speed, and later, when the sea breeze hits the city after two weeks it disperses all pollutants suspended in the air,” Beig said. He said that Mumbai’s AQI will again improve following a reversal of winds after two weeks. He also said this pattern would continue till end of winter. “Usually, during winter, the breeze is slower in speed than usual due to which particulate matters stay suspended in the lower atmosphere in the form of mist and haze leading to poor AQI,” he said.
