National Ambient Air Quality Standards

 

Use the following table to access information about the individual standards as well as the attainment status and ongoing efforts surrounding each pollutant.

 

Criteria Pollutant Primary/ Secondary Averaging Time Level Form Attainment Status
Carbon Monoxide Primary 8 – hour 9 ppm Not to be exceeded more than once per year Attainment
1 – hour 35 ppm
Lead Primary and Secondary Rolling            3 – month average 0.15 µg/m3 (1) Not to be exceeded Attainment
Nitrogen Dioxide Primary 1 – hour 100 ppb 98th percentile, averaged over 3 years Attainment 
Primary and Secondary Annual 53 ppb (2) Annual Mean
Ozone Primary and Secondary 8 – hour 0.075 ppm (3) Annual fourth-highest daily maximum 8-hour concentration, averaged over 3 years

Attainment 

(except for Baton Rouge 5- parish area that was designated marginal nonattainment in July 2012.) 

Particle Pollution PM2.5 Primary and Secondary Annual 15 µg/m3 (going to 12 µg/m3 on 3/18/13) Annual mean, averaged over 3 years Attainment
24 – hour 35 µg/m3 98th percentile, averaged over 3 years
PM10 Primary and Secondary 24 – hour 150 µg/m3 Not to be exceeded more than once per year on average over 3 years Attainment
Sulfur Dioxide Primary 1 – hour 75 ppb (4) 99th percentile of 1-hour daily maximum concentrations, averaged over 3 years Attainment   New designations expected Spring 2013)
Secondary 3 – hour 0.5 ppm Not to be exceeded more than once per year

 

(1) Final rule signed October 15, 2008.  The 1978 lead standard (1.5 µg/m3 as a quarterly average) remains in effect until one year after an area is designated for the 2008 standard, except that in areas designated nonattainment for the 1978, the 1978 standard remains in effect until implementation plans to attain or maintain the 2008 standard are approved.

(2) The official level of the annual NO2 standard is 0.053 ppm, equal to 53 ppb, which is shown here for the purpose of clearer comparison to the 1-hour standard.

(3) Final rule signed March 12, 2008.  The 1997 ozone standard (0.08 ppm, annual fourth-highest daily maximum 8-hour concentration, averaged over 3 years) and related implementation rules remain in place.  In 1997, EPA revoked the 1-hour ozone standard (0.12 ppm, not to be exceeded more than once per year) in all areas, although some areas have continued obligations under that standard (“anti-backsliding”).  The 1-hour ozone standard is attained when the expected number of days per calendar year with maximum hourly average concentrations above 0.12 ppm is less than or equal to 1.

(4) Final rule signed June 2, 2010.  The 1971 annual and 24-hour SO2 standards were revoked in that same rulemaking.  However, these standards remain in effect until one year after an area is designated for the 2010 standard, except in areas designated nonattainment for the 1971 standards, where the 1971 standards remain in effect until implementation plans to attain or maintain the 2010 standard are approved.

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