(1) Conformity determinations shall be made for the adoption, acceptance, approval, funding, or support of all transportation plans, improvement programs, and projects located in or affecting nonattainment and maintenance areas for any criteria pollutants.

(2) Regional transportation plans that contain either wholly or partially a nonattainment area for any criteria pollutant shall comply with this chapter. Transportation plans that do not contain either wholly or partially a nonattainment or maintenance area are exempt from this chapter.

(3) Transportation improvement programs shall comply with this chapter. The regional transportation improvement program shall include projects on the regional transportation system; transportation control measures of local government six-year street and road programs developed pursuant to RCW 36.81.121 and 35.77.010; and transit management plans developed pursuant to RCW 35.58.2795. Transportation improvement programs for areas that do not contain either wholly or partially a nonattainment or maintenance area for any criteria pollutants are exempt from this chapter.

(4) Projects contained in the regional transportation improvement program of a metropolitan area boundary and within a county that either wholly or partially contains a nonattainment area shall comply with this chapter. Projects not on the regional transportation system shall be considered to comply with the general provisions of this chapter; however they must be evaluated by the lead agency during compliance with the requirements of the State Environmental Policy Act (SEPA), (chapter 197-11 WAC), to determine if a conformity analysis and determination based upon this chapter is warranted. Preservation or maintenance projects in WAC 173-420-110 are exempt from the conformity requirements of this chapter.

(5) Projects on the regional transportation system that are located outside a nonattainment area but affect traffic or air quality of a nonattainment area shall comply with WAC 173-420-060, 173-420-065 and 173-420-100.