PigeonBlog

The Air quality index (AQI):

The Air quality index was developed by the EPA in 1999 in order to provide the public with meaningful information about outdoor air quality. Numbers and colors are associated with the current presence and accumulation of ozone and particulate matter by region.

AQI index number
0 to 50	good	none
51 to 100	moderate	Unusually sensitive people should consider limiting prolonged outdoor exertion.
101 to 150	unhealthy for sensitive groups	Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion./td>
151 to 200	unhealthy	Active children and adults, and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else, especially children, should limit prolonged outdoor exertion.
201 to 300	very unhealthy	Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion; everyone else especially children, should limit outdoor exertion.
301 to 500	hazardous	Everyone should avoid all outdoor exertion.

The AQI is calculated in following way:

Ozone:
If <= .05 ppm	AQI = 500 x Concentration
If > .05 <= .08 ppm	AQI = (833 x Concentration) - 16.67
If > .If > .08 ppm	AQI = (714 x Concentration) - 7.14

Particulate Matter:
If <= 30 ug/m3	AQI = 0.8333 x Concentration
If > If > 30 ug/m3	AQI = (0.5 x Concentration) + 10