Kolkata's air quality declined to 'poor' and 'very poor' levels on Wednesday due to cold weather conditions. Most monitoring stations reported deteriorating air quality throughout the day, with two stations in Ballygunge and Jadavpur falling into the 'very poor' category by evening. Doctors advised residents to limit outdoor activities due to potential respiratory health impacts. Scientists attribute the worsening air quality to a combination of factors including construction, waste burning, and pollutants trapped by low temperatures.