EPA Region 4 is the agency responsible for the state implementation plan (SIP) development (including mobile sources related issues), designation activities for the national ambient air quality standards (NAAQS), transportation conformity activity, regional haze and general air quality planning  for the States of Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, and Tennessee.

Links of Interest:

• EPA Approved Statutes and Regulations in the Mississippi SIP
• Approved Air Quality Implementation Plans in Region 4
• About SIPs
• Air Quality Implementation Plans 
• Criteria Air Pollutants (NAAQS)  
• Nonattainment Areas (Green Book)

Mississippi State Implementation Plan(SIP) Contact in the Southeastern US - Region 4: Tiereny Bell (404-562-9089)

• Mississippi SIP: Article 4 Section 109 - Mississippi Ethics Commission Advisory Opinion - NO. 95-042-E May 5, 1995 (PDF)(3 pp, 77 K, 10/1/17)
  Missippi Ethics Commission Advisory Opinion as it involves ambient air quality standards & regulations in MS + where to obtain copies of referenced federal regulations