Understanding the Beijing Air Quality Index

What is the Beijing air pollution index and what does it measure?

The station measures PM2.5 particles and ozone. "PM2.5" means particles that are smaller than 2.5 microns in size, like soot from diesel engines. Research shows that these are the most dangerous pollutants. The first part is the date and time. Then comes the measurement, then an index that is calculated from the measurement, then a health impact rating. Anything below 100 is good, anything above 100 is a cause for concern.

More information and research on the health risks posed by PM2.5 particles

What other kinds of pollution are in Beijing air ... and the risks

How to interpret the numbers?

The most important parts are the index and the rating. These are calculated according to US EPA (Environmental Protection Agency) guidelines

0-50 Good

51-100 Moderate (Unusually sensitive people should consider reducing prolonged or heavy exertion)

101-150 Unhealthy for Sensitive Groups (People with heart or lung disease, older adults, and children should reduce prolonged or heavy exertion)

151-200 Unhealthy (People with heart or lung disease, older adults, and children should avoid prolonged or heavy exertion. Everyone else should reduce prolonged or heavy exertion)

201-300 Very Unhealthy (People with heart or lung disease, older adults, and children should avoid all physical activity outdoors. Everyone else should avoid prolonged or heavy exertion)

What action to take?

Bear in mind the following points: 1) pollution is heaviest near to busy roads 2) pollution is generally less indoors, particularly if you have air cleaners. Our suggestion is to avoid walking near traffic and main roads on heavily polluted days, and to minimise time out of doors.For families planning weekend activities, consider heading out of town to the countryside rather than coming to the center of Beijing at times when pollution levels are high.

Downtown area versus Shunyi

The US embassy monitoring station is in the downtown area, in the ChaoYang district, near the NE corner of the 3rd ring road. This is the heart of the expat residential area downtown, so the air quality feed gives a good picture of the air quality for those living in the city and the Lido area. It is less accurate for Shunyi residents living further out of town. Generally the Shunyi situation can be expected to be quite closely correlated with downtown, but is often better overall since traffic density is less. There are exceptions in the winter months however, when coal burning by local Shunyi residents can sometimes make the air quality there as bad or worse than the city.

For more information...

Consult the EPA website at this link for more information on interpreting these numbers.