Patiala, Jan. 21 -- For almost three months, residents across the major cities of the state have been exposed to unhealthy air as the air quality has remained in the "moderately polluted" to "poor" categories since November, according to data from the Central Pollution Control Board (CPCB). The Air Quality Index (AQI) is categorised as good (0-50), satisfactory (51-100), moderately polluted (101-200), poor (201-300), very poor (301-400) and severe (401-500). Higher AQI values indicate worsening air quality and greater health risks. According to CPCB data, not a single day in November and December recorded good or satisfactory air quality in major cities, including Patiala, Jalandhar and Ludhiana. On most days during this period, the AQI remained above 150, while on several occasions it crossed the 200 mark, placing air quality in the poor category. Officials said that with AQI levels consistently exceeding 100, Punjab's air quality has remained in the moderate category for nearly three months. This classification indicates that prolonged exposure may cause breathing discomfort, particularly among individuals suffering from lung and heart ailments. Air quality categories are determined after assessing multiple pollutants, the most critical being particulate matter (PM) 2.5. These fine particles are small enough to penetrate deep into the lungs and bloodstream, posing serious health risks. According to the World Health Organization (WHO), prolonged exposure to PM2.5 can trigger cardiovascular and respiratory diseases, including stroke, lung cancer and chronic obstructive pulmonary disease (COPD). The CPCB data shows that on most days when AQI levels peaked, elevated PM2.5 concentrations were the primary contributor. Health experts have urged residents, particularly vulnerable groups, to remain cautious. Dr Vishal Chopra, professor and head, Chest and TB department at Government Rajindra Hospital, said people with pre-existing respiratory and cardiac conditions should take preventive measures. Meteorological officials said Punjab's air quality is likely to improve after January 22, as a strong western disturbance is expected to bring rainfall and thunderstorms between January 22 and 24. Strong winds and light showers are expected to help disperse pollutants, with AQI levels likely to drop to the 'satisfactory' category by the end of the week....