Smoke School Information in North Carolina

North Carolina Acceptance Status for VirtualOpacity^® — EPA ALT-152A

Accepted.

North Carolina Acceptance Letter »

North Carolina Visible Emissions / Opacity Standard

The opacity limit for North Carolina is Pre-July 1, 1971: 40% opacity (6-min avg) with exception structure; post-July 1, 1971: 20% (6-min avg), exceptions: no 6-min period >87%, no more than one 6-min period >20% per hour, no more than four per 24 hr, as established under 15A NCAC 02D .0521(c) (sources manufactured as of July 1, 1971) and .0521(d) (manufactured after July 1, 1971).

Compliance is demonstrated via EPA Method 9 (40 CFR 60 Appendix A, as of March 13, 1985); observer must be certified.

Averaging period: 6-minute average; exception: one 6-min period/hr, ≤4 times/24 hours

North Carolina's rule distinguishes between older sources (40%) and sources built after July 1, 1971 (20%). New post-1971 sources may seek an exception to operate at up to 40% if they demonstrate compliance with PM mass standards and no NAAQS impact. Observer certification using Method 9 as of 1985 is required.

Last verified July 8, 2026

Note: Regulations change — always verify current requirements with your state's air quality agency before making compliance decisions. This page is for informational purposes and is not legal advice; consult a qualified attorney or environmental compliance professional for guidance specific to your facility.