Ozone will be the main pollutant in many parts of China in the latter half of August, according to forecasts from the country’s National Meteorological Center.

Ozone is an atmospheric gas that when high in the stratosphere, protects lower levels from the sun’s ultra-violet rays. However, when it is at ground level — formed by a reaction of nitrogen oxides and volatile organic compounds in sunlight — it can cause health problems such as chest pain and coughing if inhaled in high concentrations. Lower concentrations can also damage materials such as rubber and plastics.

Beijing, Tianjin, and Hebei province (the Jing-Jin-Ji region) are expected to see some light ozone pollution, while the southwestern Chengdu-Chongqing region may see moderate ozone pollution due to high temperatures and strong sunlight.

Contact reporter Ren Qiuyu (qiuyuren@caixin.com)