NEW DELHI: Air quality in Delhi deteriorated on Friday, with the overall Air Quality Index (AQI) recorded at 311, placing it in the ‘very poor’ category, according to data from the Central Pollution Control Board’s (CPCB) SAMEER app. The decline in air quality came amid chilly winter conditions in the national capital, with pollutants lingering close to the ground due to unfavourable weather. Several parts of the city reported AQI levels in the poor to very poor range, raising concerns over prolonged exposure to polluted air. The India Meteorological Department (IMD) has forecast cold wave conditions at isolated places in Delhi between January 2 and 5, a development that could further affect air quality. Low wind speeds and falling temperatures are expected to restrict the dispersal of pollutants in the coming days.