Environmental Science 3(3+0)

National Ambient Air Quality Standards (NAAQS) (Source: USEPA)

Pollutant	Primary Stds.	Averaging Times	Secondary Stds.
Carbon Monoxide	9 ppm	8-hour	None
	35 ppm (40 mg/m3)	1-hour	None
Lead	1.5 µg/m3	Quarterly Average	Same as Primary
Nitrogen Dioxide	0.053 ppm (100 µg/m3)	Annual (Arithmetic Mean)	Same as Primary
Particulate Matter (PM10)	50 µg/m3	Annual (Arith. Mean)	Same as Primary
	150 ug/m3	24-hour
Particulate Matter (PM2.5)	15 µg/m3	Annual (Arith. Mean)	Same as Primary
	65 ug/m3	24-hour
Ozone	0.08 ppm	8-hour	Same as Primary
	0.12 ppm	1-hour	Same as Primary
Sulfur Oxides	0.03 ppm	Annual (Arith. Mean)	-------
	0.14 ppm	24-hour	-------
	-------	3-hour	0.5 ppm (1300 ug/m3)

• The Air Quality Index (AQI) (also known as the Air Pollution Index (API) or Pollutant Standard Index (PSI)) is a number used by government agencies to characterize the quality of the air at a given location. As the AQI increases, an increasingly large percentage of the population is likely to experience increasingly severe adverse health effects.

• To compute the AQI requires an air pollutant concentration from a monitor or model. The function used to convert from air pollutant concentration to AQI varies by pollutant, and is different in different countries. Air quality index values are divided into ranges, and each range is assigned a descriptor and a color code. Standardized public health advisories are associated with each AQI range. An agency might also encourage members of the public to take public transportation or work from home when AQI levels are high.