Kolkata, Nov 24 : With the onset of winter in Kolkata, the dipping mercury level is getting associated with deteriorating Air Quality Index (AQI) in and around the city. As per the latest figures, the level of PM 2.5 in the air has been recorded above 300, which signifies 'very poor' quality, in and around the city. On Friday, PM 2.5 levels were 310 at Victoria Memorial and 309 at Fort William, both located near the 'lungs' of the city, the Kolkata Maidan. The PM 2.5 level at Ghusuri in Howrah district, known for the presence of multiple high-polluting fabrication units, was recorded at 353. According to environment activist Somendra Mohan Ghosh, with all the CAAQMS (Continuous Ambient Air Quality Monitoring Stations) having recorded an AQI of 300 at some point in the day, a serious situation can evolve when full-fledged winter sets in in the coming days. He pointed out that with the current levels of AQI on both sides of river Ganges recorded between 300 and 400, the citizens of both Kolkata and Howrah, especially the elderly, are at high health risks. 'People might suffer from respiratory illness on prolonged exposure to poor air. AQI between 201 and 300 might trigger a health alert, meaning everyone might experience more serious health effects,' he said. According to Ghosh, only spells of unseasonal rain can bring some relief. /IANS