What are National Ambient Air Quality Standards (NAAQS) and which agencies implement them in the United States?

• A. National Ambient Air Quality Standards; EPA sets standards and states implement through SIPs.
• B. National Auto Air Quality Standards; DOT sets standards.
• C. NASA sets air quality standards.
• D. Local city councils set standards.

Answer: (A)

National Ambient Air Quality Standards are nationwide limits on outdoor air quality designed to protect public health and welfare. The Environmental Protection Agency sets these standards under the Clean Air Act, and states implement them through State Implementation Plans (SIPs) that outline how they will achieve and maintain the standards. The EPA reviews and approves these plans and can impose federal measures if a state does not meet them. This arrangement reflects the roles of the EPA in setting the standards and states in enforcing them locally through SIPs.