National Ambient Air Quality Standards
National Ambient Air Quality Standards (NAAQS) were set across the United States in the Clean Air Act of 1970. The Clean Air Act requires the Environmental Protection Agency (EPA) to set the National Ambient Air Quality Standards for pollutants considered harmful to public health and the environment.
Air pollution comes from many different sources: stationary sources such as factories, power plants, smelters, and smaller sources such as dry cleaners and degreasing operations; mobile sources such as cars, buses, planes, trucks, and trains; and naturally occurring sources such as windblown dust, and volcanic eruptions, all contribute to air pollution. Air Quality can be affected in many ways by the pollution emitted from these sources. These pollution sources can also emit a wide variety of pollutants.
The EPA has these pollutants classified as the six principal pollutants (or “criteria pollutants”). These pollutants are monitored by the EPA as well as national, state, local, and tribal organizations.
National Ambient Air Quality Standards
The Clean Air Act identifies two types of NAAQS:
- 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.
EPA’s National Ambient Air Quality Standards
National Ambient Air Quality Standards
| Pollutant (final rule cite) | Primary/Secondary | Ave. Time | Level | Form |
| Carbon Monoxide (76 FR 54294 Aug, 31 2011) | Primary | 8 hour 1 hour | 9ppm 35ppm | Not to be exceeded more than once per year |
| Lead (73 FR 66964, Nov, 12 2008) | Primary & Secondary | Rolling 3 month ave. | 0.15μ/m^3 | Not to be exceeded |
| Nitrogen Dioxide (75 FR 6474 Feb, 9th 2010) (61 FR 52852, Oct, 8th 1996) | Primary Primary & Secondary | 1 hour Annual | 100ppb 53ppb | 98th percentile averaged over 3 years Annual mean |
| Ozone (73 FR 16436 Mar, 27 2008) | Primary & Secondary | 8 hour | 0.075ppm | Annual fourth-highest daily maximum 8-hr concentration, averaged over 3 years |
| Particle Pollution PM2.5 Dec, 14 2012 PM10 | Primary Secondary Primary & Secondary Primary & Secondary | Annual Annual 24-hr 24-hr | 12 μ/m^3 15μ/m^3 35μ/m^3 150μ/m^3 | Annual mean averaged over 3 years Annual mean averaged over 3 years 98th percentile averaged over 3 years Not to be exceeded more than once per year on an average of 3 years |
| Sulfur Dioxide (75 FR 35520 Jun, 22nd 2010) (38 FR 25678 Sept, 14 1973) | Primary Secondary | 1 hour 3 hour | 75ppb 0.5ppm | 99th percentile of 1-hour daily maximum concentrations, averaged over 3 years Not to be exceeded more than once per year |
Measuring and Comparing Pollution to the National Ambient Air Quality Standards
As sovereign nations, Indian lands located in Wisconsin are not managed by the state. However, pollutants from pollution sources such as factories and power plants, located outside the reservation, can have great impacts on the quality of air over the reservation. And, while there may not be any major pollution sources located on tribal lands, a reservation may be designate as being in non-attainment for the pollutant due to transport of emissions downwind from a factory or power plant located off the reservation.
The Bad River Band of Lake Superior Chippewa monitor for two of the criteria pollutants – ground-level (tropospheric) ozone and fine particulates. Over time, measurements can be compared to the National Ambient Air Quality Standards and trends can be observed.
As long as monitored values remain below the National Ambient Air Quality Standards, the monitored area is considered “in attainment” for that particular pollutant. When monitored values rise above the National Ambient Air Quality Standards, the monitored area is considered out of attainment, or “in nonattainment”.
Areas in Nonattainment for the National Ambient Air Quality Standards
EPA must designate areas as meeting (attainment) or not meeting (nonattainment) the standard. The Clean Air Act (CAA) requires states to develop a general plan to attain and maintain the NAAQS in all areas of the country and a specific plan to attain the standards for each area designated nonattainment for a NAAQS. These plans, known as State Implementation Plans (SIPs), are developed by state and local air quality management agencies and submitted to EPA for approval.
The State Implementation Plans serve two main purposes:
- Demonstrate that the state has basic air quality management program components in place to implement a new or revised NAAQS.
- Identify the emission control requirements the state will rely upon to attain and/or maintain the primary and secondary NAAQS.
Green Book Nonattainment Areas for Criteria Pollutants
