National Ambient Air Quality Standards (NAAQS) - Attainment Status

The Clean Air Act, which was last amended in 1990, requires the United States environmental protection agency (USEPA) to set National Ambient Air Quality Standards (40 CFR part 50) for pollutants considered harmful to public health and the environment. The Clean Air Act identifies two types of national ambient air quality standards. Primary standards provide public health protection, including protecting the health of "sensitive" populations such as asthmatics, children, and the elderly. Secondary standards provide public welfare protection, including protection against decreased visibility and damage to animals, crops, vegetation, and buildings.

The USEPA has set National Ambient Air Quality Standards for six principal pollutants, which are called "criteria" air pollutants. Periodically, the standards are reviewed and may be revised. The current standards are listed below. Units of measure for the standards are parts per million (ppm) by volume, parts per billion (ppb) by volume, and micrograms per cubic meter of air (µg/m3).

Fact Sheets

Pollutant Primary/Secondary
Standards
Averaging TimeLevel Level Form Ohio Attainment Status
Carbon monoxide primary Eight-hour 9 ppm
(10 mg/m3)
Not to be exceeded more
han once per year
Full Attainment
One-hour 35 ppm
(40 mg/m3)
Full Attainment
Lead primary
and
secondary
Rolling three-month
Average
0.15 µg/m3 Not to be exceeded Full Attainment
Nitrogen dioxide primary 
and 
secondary
Annual
(Arithmetic mean)
0.053 ppm
(100 /m3)
Annual Mean Full Attainment
primary one-hour 100 ppb 98th percentile of 1-hour daily
maximum concentrations,
averaged over 3 years
Full Attainment
Particulate matter PM10 primary 
and 
secondary
24-hour 150 µg/m3 Not to be exceeded more than
once per year on average over 3 years
Full Attainment
PM2.5 primary  2012 annual
(Arithmetic mean)
12.0 µg/​m3
(2012 Std.)
annual mean, averaged over 3 years Map
secondary 1997 annual
(Arithmetic mean)
15.0 µg/​m3
​(1997 Std.)
annual mean, averaged over 3 years Full Attainment
primary 
and 
secondary
24-hour 35 µg/​m3
(2006 Std.)
annual mean, averaged over 3 years Full Attainment 
 
Ozone
primary 
and 
secondary
 Eight-hour 0.070 ppm
(2015 std)
Annual fourth-highest daily
maximum 8-hour concentration,
averaged over 3 years
Map
primary 
and 
secondary
Eight-hour 0.075 ppm
(2008 std)
Annual fourth-highest daily
maximum 8-hour concentration,
averaged over 3 years
Full Attainment
primary 
and 
secondary
Eight-hour 0.08 ppm
(1997 std)
Annual fourth-highest daily
maximum 8-hour concentration,
averaged over 3 years
Full Attainment
Sulfur dioxide primary One-hour 75 ppb Not to be exceeded more than
once per year
Map
secondary three-hour 0.5 ppm Not to be exceeded more than
once per year
Map