Contact Us

Panel: Steve Risotto
Media: Sarah Scruggs

Regulation of Hazardous Air Pollutants (HAPs)

In 1990 Congress enacted a sweeping set of changes to the federal Clean Air Act. Among these changes was a new regulatory program designed to reduce HAP emissions. The 1990 legislation included a list of 189 chemicals and chemical categories that are classified as HAPs, including a handful of common solvents. The HAP list can be found here.

One common myth about the HAP list is that all HAPs are highly toxic. In fact, the HAP list includes compounds with a wide range of toxicity. Some of the listed compounds are widely recognized to be very hazardous while others, including many of the listed solvents, are generally considered to have relatively low toxicity.

Under the Clean Air Act, EPA is required to develop air emissions regulations that apply to “major sources” of HAP emissions. A major source is any facility that has the potential to emit, on an annual basis, 10 or more tons of any single HAP or 25 tons of all HAPs combined. These regulations are often referred to as “MACT standards” because they are based on “maximum achievable control technology” (MACT).

EPA has developed  MACT standards on an industry-by-industry basis, including standards for numerous coating operations. Citations to many of these standards are found in the table below.

Summary of Existing and Proposed Coatings-Related Standards for Hazardous Air Pollutants

Source Category 40 C.F.R. Part 63, Subpart Final Rule Compliance Date
Aerospace GG 60 Fed. Reg. 45948
(Sept. 1, 1995)
Sept. 1, 1998
Magnetic Tape EE

59 Fed. Reg. 64580
(Dec. 15, 1994)

Dec. 15, 1997
Printing &
KK 61 Fed. Reg. 27132
(May 30, 1996)
May 30, 1999
Shipbuilding &
Ship Repair
II 60 Fed. Reg. 64339
(Dec. 15, 1995)
Dec. 16, 1996
Wood Furniture JJ 60 Fed. Reg. 62930
(Dec. 7, 1995)
Nov. 21, 1997
Boat Manufacturing VVVV 66 Fed. Reg. 44217
(Aug. 22, 2001)
Aug. 22, 2004
Large Appliances NNNN 67 Fed. Reg. 48253
(July 23, 2002)
July 23, 2005
Metal Coil SSSS 67 Fed. Reg. 39793
(June 10, 2002)
June 10, 2005
Fabric Printing,
Coating & Dyeing

68 Fed. Reg. 32171
(May 29, 2003)

May 29, 2006
Metal Can KKKK

68 Fed. Reg. 64431
(November 13, 2003)

November 13, 2006
Metal Furniture

68 Fed. Reg. 28605
(May 23, 2003)

May 23, 2006
Metal Parts & Products

69 Fed. Reg. 129
(January 2, 2004)

January 2, 2007
Miscellaneous Coating

68 Fed. Reg. 69163
(December 11, 2003)

December 11, 2006
Paper &
Other Web

67 Fed. Reg. 72329
(December 4, 2002)

December 4, 2005
Wood Building Products QQQQ

68 Fed. Reg. 31746
(May 28, 2003)

May 28, 2006
Auto & Light Duty Truck IIII

69 Fed Reg. 22601
(April 26, 2004)

April 26, 2007
Plastic Parts PPPP

69 Fed. Reg. 20968
(April 19, 2004)

April 19, 2007

It is important to recognize that these MACT standards do not prohibit the use of any HAP solvents. Rather, EPA’s regulations focus on the amount of HAPs that may be emitted into the air – not on the amount that may be used. For this reason, a facility always has the option of installing a control device to meet the regulations. Where a control device is not feasible (either technically or economically), the rules typically establish a limit on the amount of HAP solvents that a specific type of coating may contain. In these cases, solvent users may need to reduce their usage of HAP solvents, but they are not required to eliminate them.

EPA has recognized that, in some cases, the use of HAP solvents may help reduce VOC emissions. In its rulemaking on shipbuilding coatings, EPA noted that a formulator might need to use HAP solvents in order to reduce the VOC content of a coating. See 59 Fed. Reg. at 62688. The Agency addressed this issue by setting identical limits for the VOC and HAP content of coatings covered by the rule. This approach encourages the use of more efficient solvents, even though the Agency recognized that several of these solvents are listed as HAPs.

EPA has the authority to add or remove chemicals from the Clean Air Act HAP list, and any person may petition EPA to remove a substance from the HAP list. Such petitions currently are under review for ethylene glycol butyl ether (EGBE), methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK). Proposals to grant the MEK and EGBE petitions have been published in the Federal Register.* The MIBK petition is under review.

In addition to the federal HAP program, most states have their own air toxics programs. Although state definitions (including exemptions) are generally the same as the EPA definition, a solvent user should be aware of the precise definition that applies in his or her state.

*MEK- 68 Fed. Reg. 32606 (May 30, 2003); EGBE- 68 Fed Reg. 65648 (November 21, 2003)


News & Resources

View our resource center to find press releases, testimonies, infographics and more.