Nanjing Air Quality (AQI)

Nanjing sits at a geographic inflection point: far enough inland to lose Shanghai's oceanic ventilation, yet positioned in the flat Yangtze River Delta plain where cold air pools easily during winter. When anticyclonic high-pressure systems stall over eastern China (a common winter pattern), Nanjing can go 10–15 days with minimal wind — long enough for industrial and vehicle emissions to accumulate to hazardous levels.

The city is China's most historically significant petrochemical hub outside Beijing. SINOPEC's Jinling Petrochemical Company — one of China's largest refineries at 15 million tonnes/year capacity — sits within the urban boundary. The Nanjing Chemical Industrial Park hosts over 200 chemical manufacturers across 45 km², generating a complex cocktail of VOCs and NOₓ that react photochemically to produce ozone in summer and secondary aerosols year-round.

Nanjing Iron & Steel (南京钢铁) contributes significant PM2.5 and SO₂. Unlike Beijing and Shanghai, which have largely relocated heavy industry outside city limits, Nanjing still operates major smelting facilities near residential areas in the Qixia and Pukou districts.