IDEM: Attainment and Redesignations

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Governor Mitch Daniels

IDEM > Monitoring > Air Monitoring > Attainment and Redesignations Attainment and Redesignations

Air Quality Attainment Designations for Federal Health Standards

Nonattainment Area Designation: What does it mean and how does it happen?

US Environmental Protection Agency (EPA) has set National Ambient Air Quality Standards (NAAQS) for six common air pollutants, also called "criteria" pollutants. The criteria pollutants are carbon monoxide, nitrogen dioxide, ozone, lead, particulate matter and sulfur dioxide. NAAQS are often referred to as federal health standards for outdoor air.

The Clean Air Act, which was passed in 1970 and last amended in 1990, requires the EPA to set NAAQS for pollutants that cause adverse effects to public health and the environment. The Clean Air Act established primary and secondary air quality standards. Primary standards protect public health, including the health of "sensitive" populations such as asthmatics, children, and the elderly. The primary standard is often referred to as the health standard. Secondary standards protect public welfare, including protection against decreased visibility, damage to animals, crops, vegetation, and buildings. Standards are reviewed periodically to ensure that they include the most recent scientific information.

Nonattainment areas are regions within the country where the concentration of one or more criteria pollutants exceeds the level set as the federal air quality standards. Once the EPA announces that an area does not meet the health standard, the State works with businesses, local governments, and the public to reduce the emissions from sources contributing to the nonattainment status of the area.

Setting the Standards How does the process work?

EPA technical staff draft the air quality standards. The technical staff undertake an extensive review based on scientific and technical data to determine the level of the pollutant below which human health effects are unlikely. Congress decided, and the Supreme Court upheld, that EPA may not consider cost when setting or revising air quality standards.

EPA then obtains input from people with interest and experience in air quality and public health. Representatives of the scientific community, industry, public interest groups, the public, and the Clean Air Scientific Advisory Committee a Congressionally mandated group of independent scientific and technical experts conduct reviews of any standards proposed by EPA staff.

Before the EPA Administrator announces a final decision on the standards, the proposed standards are published in the federal register for public review and comments.

Once outdoor air quality standards are announced as final, the Clean Air Act sets a basic schedule for achieving the standards, and in some cases, requirements to meet the standards. The states have primary responsibility for selecting programs most likely to improve air quality.

How is an area designated as nonattainment?

State and local governments monitor the air to determine the level of pollution in outdoor air. The Clean Air Act requires that no later than one year after promulgation of a new or revised national ambient air quality standard, the governor of each state must submit a listing of all areas within their state that could be designated as:

nonattainment (monitored values above the standard);
attainment (monitored values below the standard); or
unclassifiable (insufficient information to make a determination).

A region that does not meet the standard is considered a nonattainment area. Within one year of the governor's submittal, EPA is to announce a list of federally designated nonattainment areas. States may contest the designation of any areas within their borders that were not included in their own submissions. The public has the opportunity to comment on proposed plans before the EPA makes a final decision.

Resources:

Planning Emission Reductions - What happens when an area doesn't meet the standards?

If a state has nonattainment areas within its borders, the state must submit a plan to EPA detailing steps necessary to achieve the standard. This plan is referred to as the State Implementation Plan, or SIP. SIPs must include an inventory of emissions, enforceable emission limitations, related control measures, and schedules and time-tables for compliance that are necessary for the area to meet the Clean Air Act standards and opportunities for public input.

Air monitoring is conducted to measure whether standards are being met. Generally, the SIP also includes modeling to demonstrate that the measures selected by the state will reduce emissions enough for the area to meet the standard. In addition, the Clean Air Act requires major sources of air pollution to meet stricter emission control requirements in nonattainment areas than are required in areas that meet federal health standards. For example, new sources of air pollution in nonattainment areas must meet stricter permitting requirements.

What steps are required to move an area from nonattainment to attainment?

States may ask EPA to redesignate an area back into attainment if:

the area has monitored attainment of the air quality standard;
the area has a fully approved State Implementation Plan;
EPA has determined that the improvement in air quality is due to permanent and enforceable reductions in emissions;
the state has submitted, and EPA has approved, a maintenance plan for the area; and,
the area has met all other applicable Clean Air Act requirements.

The EPA may approve or deny the redesignation request based on air monitoring information, the activities listed in the SIP, and the comments submitted by the public.

How do redesignated areas keep the air clean?

Nonattainment areas that later are designated to attainment are considered maintenance areas. The steps to maintain air quality are defined in a maintenance plan. Generally, the control measures used to improve air quality will remain in place.

The maintenance plan must demonstrate continued compliance, considering projected growth, for a period of ten years. If outdoor air monitors record a violation of the standard, the maintenance plan includes a commitment to determine appropriate measures to address the cause of the violation.