Table 1. Individual Air Quality Index standards of PM_2.5 ^*.

Individual Air Quality Index (AQI) Values	AQI Levels	Levels of Health Concern	24 Hour Average PM2.5 Concentrations Range (µg/m3)	Health Implications
0 to 50	Level 1	Good	0 to35	Air quality is considered satisfactory, and air pollution poses little or no risk.
51 to 100	Level 2	Moderate	35 to 75	Air quality is acceptable, but for some pollutants, there may be a moderate health concern for a very small number of people. People who are unusually sensitive to ozone may experience respiratory symptoms.
101 to 150	Level 3	Unhealthy for Sensitive Groups	75 to 115	Although the general public is unlikely to be affected in this AQI range, people with lung disease, older adults and children are at a greater risk from exposure to ozone; those with heart and lung disease, older adults and children are at greater risk from airborne particles.
151 to 200	Level 4	Unhealthy	115 to 150	Everyone may begin to experience adverse health effects, and members of the aforesaid sensitive groups may experience more serious effects.
201 to 300	Level 5	Very Unhealthy	150 to 250	This situation would trigger a health alert, signifying that everyone may experience more serious health effects.
301 to 500	Level 6	Hazardous	above 250	This would trigger a health warning of emergency conditions, and the entire population is more likely to be affected.

^*From Ambient Air Quality Standards (GB 3095–2012) and Technical Regulation on Ambient Air Quality Index (HJ 633–2012, on trial) from the website of the Ministry of Environmental Protection, China (http://kjs.mep.gov.cn/hjbhbz/bzwb/dqhjbh/dqhjzlbz/201203/W020120410330232398521.pdf and http://kjs.mep.gov.cn/hjbhbz/bzwb/dqhjbh/jcgfffbz/201203/W020120410332725219541.pdf).