40 CFR 63 Subpart HHHHHH: EPA Paint Stripping and Coating (6H)

Regulatory citation: 40 CFR Part 63, Subpart HHHHHH, National Emission Standards for Hazardous Air Pollutants: Paint Stripping and Miscellaneous Surface Coating Operations at Area Sources

What Is the 6H Rule?

Subpart HHHHHH, known as the 6H rule, is an area source air toxics standard for three activities. It covers paint stripping with chemical strippers that contain methylene chloride (MeCl), autobody refinishing, meaning spray coating of motor vehicles and mobile equipment, and spray coating of metal or plastic parts with coatings that contain target HAP. The target HAP are compounds of chromium, lead, manganese, nickel and cadmium.

A coating contains target HAP if it has 0.1 percent or more by mass of cadmium, chromium, lead or nickel, or 1.0 percent or more by mass of manganese. Area sources are sources that are not major sources, meaning they emit less than 10 tons per year of any single HAP and less than 25 tons per year of combined HAP.

Why the 6H Rule Matters

Overspray can carry toxic metals into the air, and methylene chloride is a hazardous solvent. Trained painters, good booths and efficient guns cut emissions and exposure.

Core Requirements

1. Confirm Applicability and Exclusions (63.11169–63.11170)

The rule does not cover individuals coating their own vehicles, possessions or property as a hobby or for maintenance. However, anyone who spray coats more than two motor vehicles or pieces of mobile equipment in a year is covered, whether or not they are paid. Facility maintenance, research and laboratory work, and quality control activities are also excluded.

2. Train and Certify Painters (63.11173(e)(1), (f) and (g))

Only painters certified as trained may spray apply coatings. Training must include hands-on and classroom instruction on spray gun selection, setup and operation, spray technique to improve transfer efficiency and reduce overspray, routine booth and filter maintenance, and environmental compliance. New painters must be trained within 180 days of hiring. Refresher training and recertification are required every five years.

3. Spray in a Compliant Booth (63.11173(e)(2))

Spray booths must have filters that capture at least 98 percent of overspray. Booths for complete motor vehicles or mobile equipment must have a full roof, four complete walls or side curtains and operate at negative pressure, with a limited exception for fully sealed booths with automatic pressure balancing. Booths for miscellaneous parts must have a full roof and at least three complete walls or side curtains. Spot repairs can use a mobile enclosure that directs overspray to a filter.

4. Use Efficient Spray Guns (63.11173(e)(3))

Coatings must be applied with high-volume low-pressure (HVLP), electrostatic, airless or air-assisted airless spray guns, or an equivalent technology approved in writing by EPA.

5. Clean Guns Without Atomizing Solvent (63.11173(e)(4))

Spray gun cleaning must not create an atomized mist or spray of solvent and paint residue outside a container that collects the used solvent.

6. Minimize Methylene Chloride in Paint Stripping (63.11173(a)–(d))

Shops that strip paint with MeCl must evaluate whether stripping is needed, consider alternatives, reduce exposure of the stripper to air, optimize application conditions and store and dispose of strippers properly. Operations using more than one ton of MeCl per year must also write and follow a MeCl minimization plan and post a placard in each stripping area.

7. Submit Notifications and Reports (63.11175–63.11176)

Covered sources must submit an initial notification. New sources submit within 180 days after startup, or within 120 days after becoming subject, whichever is later. An annual notification of changes report is due before March 1 in any year where information in earlier notifications has changed. Notifications and reports are submitted electronically through EPA's CEDRI system.

8. Keep Records for Five Years (63.11177–63.11178)

Keep painter training certifications, booth filter efficiency documentation, spray gun documentation where needed, copies of notifications and reports, and records of any deviations. Paint strippers must keep MeCl usage records. Records must be kept for five years, with the first two years on site.

Common Compliance Approaches

Keep a Training Roster

List every painter by name and job description, with the date of initial training and the next five-year refresher.

Buy Documented Filters and Guns

Keep the filter manufacturer's 98 percent capture efficiency data and the spray gun specifications in the compliance file.

Screen Coatings Before Use

Review safety data sheets for chromium, lead, manganese, nickel and cadmium content before adding a new coating.

Example: 6H Compliance in Practice

An auto body shop with two paint booths sends its four painters to a training course covering spray technique, gun setup, booth maintenance and the 6H rule. The shop manager keeps the certificates and sets reminders for refresher training in five years. The booths use filters rated at 98 percent capture, and painters use HVLP guns cleaned in an enclosed gun washer. When the shop adds a third booth, it files an annual notification of changes report before March 1.

Related regulations: EPA Hazardous Waste Generators, EPA Title V Operating Permits, EPA Lead RRP Rule.

Note: Separately, EPA's 2024 methylene chloride rule under the Toxic Substances Control Act prohibited most industrial and commercial uses, including paint and coating removers. In September 2026, the U.S. Court of Appeals for the Fifth Circuit vacated that rule and sent it back to EPA, and further review is possible. A 2019 TSCA rule on consumer paint and coating removers is separate. Check the current status of these rules before using MeCl strippers. State and local air agencies may add stricter requirements.

Frequently Asked Questions

Do auto body painters need to be certified?

Yes. Under 63.11173(e)(1), only painters certified as trained may spray apply coatings at covered operations. Training must be completed within 180 days of hire and refreshed every five years.

What filter efficiency does a spray booth need?

Filters must capture at least 98 percent of overspray. Water wash booths operated to the manufacturer's specifications are an accepted alternative.

Does the 6H rule require a Title V permit?

No. Under 63.11174(b), area sources subject to this subpart do not need a Part 70 or 71 permit unless they need one for another reason.