Tracking China’s air quality

China’s problems with air pollution – particularly in Beijing – have been well documented.

At points over this winter in north China readings of the most harmful types of toxic smog have reached 40 times the level recommended by the World Health Organisation.

Using data collected by the US State Department, this interactive graphic tracks the air quality of five of China’s major cities: Beijing, Chengdu, Guangzhou, Shanghai and Shenyang.

Air Quality Index is the measure used by the Environmental Protection Agency and many local authorities in the US to assess pollution and warn people when it reaches hazardous levels. The AQI takes account of the five most important pollutants: ozone, microscopic particles, carbon monoxide and sulphur dioxide.

Levels below 100 are considered acceptable. Levels between 100 and 150 will not affect the general population but may affect sensitive groups, such as those with lung disease. The main impact of air pollution is on the pulmonary and respiratory system.

An air quality reading above 150 is considered unhealthy for everyone; above 200 is “very unhealthy”. Above 300 is “hazardous” and in the US would trigger emergency warnings for people to avoid exercise and if possible remain indoors.

Click on the city names to show or hide each individual AQI.