By Susan Bassett

Manufacturers of reinforced plastic composites must reduce hazardous air pollutant (HAP) emissions under a new maximum achievable control technology (MACT) rule published by the U.S. Environmental Protection Agency (EPA) on April 21, 2003 (68 FR 19375). Facilities must comply with the new rule if they meet both of the following criteria:

• Use at least 1.2 tons per year (tpy) of combined thermoset resins and gel coats containing styrene, and
• Are located at a major source of HAPs (i.e., they have the potential to emit 10 tpy of a single HAP [typically styrene] or 25 tpy of combined HAPs).

As defined by EPA, the term "reinforced plastic composites production" also includes manufacturing of nonreinforced plastic molded products using thermoset resins and/or gel coats containing styrene. The new regulations can be found in Title 40, Part 63, Subpart WWWW (four "W"s) of the Code of Federal Regulations. Most facilities will begin meeting the new emission limits by an April 21, 2006 deadline.

Pollutant emissions from many types of processes are regulated, including emissions from open and closed molding, centrifugal casting, continuous casting or lamination, pultrusion, manufacturing of sheet molding or bulk molding compound, material storage and mixing operations, and equipment cleaning. Facilities can choose from a variety of compliance options. Pollution prevention options focus on low-emitting materials and manufacturing methods. Although most facilities can comply using pollution prevention techniques, a few facilities must install and operate emission capture and control systems.

Using low-HAP resins and gel coats and low-emitting application methods is the first pollution prevention technique. Allowable HAP-content limits vary depending on the type of manufacturing process, type of resin/gel coat and application method, and whether vapor suppressants are used. If HAP concentrations in all resins and gel coats fall below specified limits, compliance is based on documenting HAP concentrations. Alternatively, facilities needing more flexibility in choosing resins and gel coats can take another pollution prevention approach based on averaging high- and low-HAP materials. Using equations provided in Subpart WWWW, facilities calculate emissions from multiple resins and gel coats and demonstrate that average emissions do not exceed specified emission limits. Compliance is based on 12-month rolling average emissions.

Installation and operation of emission capture and control equipment, such as thermal oxidizers and/or adsorbers, is a third compliance option. Depending on the type of manufacturing process, required HAP emission reductions vary from 58.5 percent to 95 percent. Facilities using emission control devices must continuously monitor and document equipment performance.

At most facilities, employees will implement work practices contained in the rule. Examples of work practices include 1) using only HAP-free cleaning solvents (except when cleaning resin/gel coat application equipment or when cleaning occurs in a closed system), and 2) keeping containers closed when mixing resins and other HAP-containing materials. Employees also will comply with planning, recordkeeping, reporting, and permitting requirements contained in the new regulations.

For more information on environmental issues and composites, see the Environment, Safety, and Health directory.

About the Author

Susan Bassett is a Principal at Cogent Regulatory Science, Inc. (Cogent). Before focusing on air quality compliance, Ms. Bassett worked as a chemical engineer for 3M Company, the U.S. Air Force, and Sierra Cast, Inc. A nationally recognized expert in explaining intricate U.S. EPA regulations, she has authored many air quality compliance articles in Composites Technology and Pollution Engineering industry magazines. In the early 1990s, Ms. Bassett edited The Air Pollution Consultant, which addressed emission control technologies, air-related court cases, permitting and enforcement procedures, and federal air quality regulations.