Part 5 of the Clean Air Act series from Compliance Assurance Associates, Inc. (CAA). Read Part 1 on Title V Permits, Part 2 on State Implementation Plans, Part 3 on New Source Performance Standards, and Part 4 on National Ambient Air Quality Standards.

Understanding Nonattainment Areas Under the Clean Air Act

When an area fails to meet the National Ambient Air Quality Standards (NAAQS) for one or more criteria pollutants, the Environmental Protection Agency (EPA) may designate it as a nonattainment area. That designation sits within a regulatory hierarchy that predates — and sits above — facility-level permitting, and understanding where it fits can help Clients avoid a common source of compliance risk.

Under the Clean Air Act, NAAQS establish the baseline air quality standards each state must meet. Beginning in the early 1970s, states were required to submit State Implementation Plans (SIPs) describing how they would achieve and maintain those standards, and some states issued their own operational permits under individual state air statutes during this period. The Clean Air Act Amendments of 1990 later directed states to issue Title V permits to major emission sources, creating a permitting layer that is distinct from — and explicitly subordinate to — NAAQS and SIP requirements. Title V permits were not designed to, and cannot legally, supersede or replace NAAQS or SIP obligations.

That distinction matters for facility operators. Over time, permitting compliance is sometimes mistaken for full compliance with underlying NAAQS and SIP requirements. In nonattainment areas, where SIP and NAAQS obligations are typically more stringent, that mistaken assumption can create compliance exposure that goes beyond permitting and may affect expansion plans, project timelines, and long-term compliance strategy.

What Is a Nonattainment Area?

A nonattainment area is a geographic region — often a county, part of a county, or a multi-county metropolitan area — where monitored air quality does not meet the NAAQS for at least one criteria pollutant. These pollutants may include ozone, particulate matter, carbon monoxide, sulfur dioxide, nitrogen dioxide, or lead.

Nonattainment areas are often classified by severity. For ozone, classifications may include marginal, moderate, serious, severe, or extreme. The classification level helps determine the NAAQS and SIP requirements — including permitting obligations, control requirements, and planning deadlines — that apply in that area.

How Nonattainment Designations Affect Facility Operations

Operating in a nonattainment area can change the compliance landscape in several ways:

  • New or modified sources may be subject to Nonattainment New Source Review (NNSR), which generally requires more rigorous permitting than standard New Source Review
  • Facilities may need to secure emissions offsets, which means reducing emissions elsewhere to help compensate for new or increased emissions
  • Lowest Achievable Emission Rate (LAER) standards may apply, which are typically more stringent than Best Available Control Technology (BACT) requirements used in attainment areas
  • SIPs for nonattainment areas may include additional monitoring, recordkeeping, reporting, or operational requirements specific to that region

For facility operators, this means nonattainment status is not just a regional air quality label. It can directly affect permitting strategy, project timelines, control technology decisions, and ongoing compliance planning — independent of, and in addition to, whatever a facility's Title V permit already requires.

Multi-State Compliance Challenges

For Clients operating facilities across multiple states, nonattainment status adds another layer of complexity. Nonattainment boundaries, classification levels, and SIP requirements vary by state and even by region within a state. A facility in good standing in one location may face materially different obligations just across a state line.

This can be especially important for companies managing multiple facilities, shared compliance teams, or standardized operating procedures across jurisdictions. Relying on assumptions from one state or region — or on the assumption that a Title V permit fully captures NAAQS and SIP obligations — can increase the risk of missing a location-specific requirement.

Key Points

  • Nonattainment areas are regions that do not meet the NAAQS for one or more criteria pollutants
  • NAAQS and SIP requirements sit above Title V permitting, and Title V permits cannot legally supersede or replace them
  • Classification severity helps determine applicable permitting, control, and planning requirements
  • New or modified sources in nonattainment areas may face NNSR, emissions offset requirements, and LAER standards
  • SIP requirements can vary significantly by state and region
  • Multi-state operators need a clear process for tracking requirements across jurisdictions

Navigating Nonattainment Requirements Across Multiple States

Compliance Assurance Associates, Inc. (CAA) helps Clients manage visible emissions compliance across facility locations, including support for observer training, Method 9 certification, and accessible certification records.

For Clients operating in multiple jurisdictions, maintaining clear records and current observer certifications can support a stronger compliance program, especially when local requirements vary by area. CAA's VirtualOpacity® platform helps support centralized access to observer certification records, making it easier for teams to stay organized across facility locations.

To learn more about how CAA supports visible emissions compliance, email or call our team.

About CAA

Compliance Assurance Associates, Inc. (CAA) is a nationally recognized provider of smoke school training and opacity certification, helping facilities navigate visible emissions requirements embedded in Title V permits, State Implementation Plans, and nonattainment area compliance obligations.