Smoke School Information in Massachusetts

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

Pending Acceptance.

Massachusetts Visible Emissions / Opacity Standard

The opacity limit for Massachusetts is 20% opacity general standard, brief exceedance to 40% for <=2 min/hr; boiler alternative option: 15% with 27% short-period allowance, as established under 310 CMR 7.06(1)(b) (general); boiler alternative at 7.06(1)(c).

Compliance is demonstrated via EPA Method 9 (40 CFR Part 60, Appendix A-4) or visible emission monitor.

Averaging period: General: <=40% for <=2 min in any hour; boiler alt: 15%/27% structure per 7.06(1)(c)

Massachusetts has the most stringent general visible emissions standard in the country at 15% opacity (vs. the common 20%). This is a critical note for regulated facilities. Boilers have more complex startup/shutdown provisions. Marine vessels subject to 310 CMR 7.06(1)(a) and (b).

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.