If you are a composite parts manufacturer subject either to the boat manufacturing or the reinforced plastic composites production Maximum Achievable Control Technology (MACT) standards, one of the easiest ways to meet them is to use "compliant" resins and gel coats. Demonstrating compliance takes as few as two steps for each resin or gel coat. First, you determine the organic hazardous air pollutant (OHAP) concentration of the purchased resin or gel coat. Second, you document that this concentration is less than the relevant MACT limit.

Typically, step one can be accomplished by checking vendor-supplied information, a task that may be as simple as picking a single number off of a product data sheet or it may require chemical knowledge and calculations. (Either way, relying on vendor data is much faster and less expensive than the alternative: testing each resin and gel cost using analytical methods approved by the U.S. Environmental Protection Agency!)

When you fill out MACT compliance forms, you should report total OHAP content, measured in weight-percent (wt-%). In the simplest case, resin and gel coat vendors will have supplied air-quality-oriented product data sheets that state chemical composition in terms of regulated air pollutants. For instance, Valspar Composites (Elkhart, Ind., U.S.A.) supplies "certified product data sheets" with initial gel coat shipments. The company's NEXTERRA Larson White gel coat, for example, is a low-VOC product with extremely low OHAP content. Its data sheet states that the gel coat contains 0.32 percent volatile HAPs (VHAPs) by weight and 18.7 percent VOCs by weight.

Note that terminology sometimes varies slightly. In this example, Valspar reports total VHAPs rather than OHAPs, but organic HAPs and VHAPs are both volatile carbon-containing HAPs. Notice that concentration data also is given for volatile organic compounds (VOCs) and, while these numbers are useful when reporting VOC emissions under other air quality programs, they should not be used in MACT compliance reports. OHAPs are essentially a subset of VOCs. If you use the VOC content, then you may be overestimating OHAP emissions.

Composite parts manufacturing facilities that use this NEXTERRA product would report 0.32 wt-% OHAP to demonstrate that this is a MACT-compliant gel coat. Compared to the 33-percent limit for pigmented gel coats, this gel coat beats the boat manufacturing MACT standard by two orders of magnitude. (The 33-percent OHAP limit for compliant marine gel coats is found in Table 2 within 40 Code of Federal Regulations [CFR] Part 63, Subpart VVVV.)

While air-quality data sheets are easiest to use, in most cases, you will be supplied with a Material Safety Data Sheet (MSDS). Resin and gel coat manufacturers are legally required to provide MSDSs, but are not required to provide air quality data sheets. Originally developed under Occupational Safety and Health Administration (OSHA) regulations, MSDSs are designed to explain potential dangers to workers who handle chemicals. Consequently, you may need to work a little harder to determine OHAP content. MSDSs report chemical content in terms of individual chemicals and mixtures. Concentration data is typically found near the beginning of an MSDS.

To determine OHAP content, you need to identify which of the listed chemicals are OHAPs and then add the weight-based percentages together. OHAPs include only those HAPs that contain carbon atoms and are volatile. (A list of all HAPs and their Chemical Abstract Service [CAS] registry numbers can be found at www.epa.gov/ttn/atw/orig189.html.) The three most common OHAPs in resins and gel coats are styrene (CAS 100-42-5), methyl methacrylate (MMA, CAS 80-62-6) and methylene chloride (also known as dichloromethane, CAS 75-09-2).

The accompanying table shows a portion of the MSDS information for HK Research Corp.'s (Hickory, N.C., U.S.A.) HydroShield Lite White Gel Coat. The first three columns of this table are relevant to MACT compliance. Looking at the "ingredients" column, there are two OHAPs: styrene monomer and methyl methacrylate (MMA). The weight percents for styrene monomer and MMA are 27 and 3, respectively. In this case, then, the total OHAP content is 30 wt-%, which is below the boat manufacturing MACT limit of 33 wt-% for pigmented gel coats. In many cases, styrene will be the only OHAP listed in your resin or gel coat formulation. If so, then total OHAP content equals the styrene content.

Note, again, that terminology may differ. If you questioned whether styrene monomer mentioned in the above example is the same chemical as styrene, you could have compared CAS numbers to see if they match. This can be a little tricky because CAS number formats vary. They can be shown with or without hyphens, and may include leading zeros (as in the table shown here). Simply read the numbers from right to left, excluding all hyphens and the left-most string of zeros. If they match, the chemicals are the same.

Regulatory instructions for determining total OHAP content are located in §63.5758 of the boat manufacturing MACT and in §63.5797 of the reinforced plastic composites production MACT. The regulations address several circumstances, such as how to determine total OHAP content when the MSDS provides a range of concentrations. For example, if the styrene content of a resin is listed as "30-32 wt-%," the maximum concentration (32 wt-%) must be used when calculating total OHAP content.

In some cases, de minimis OHAP concentrations can be ignored. If an OHAP accounts for less than 1.0 wt-% of the resin or gel coat, it does not need to be counted toward the total OHAP concentration as long as the OHAP is not an OSHA-defined carcinogen. When the OHAP is considered carcinogenic, its concentration must be included in the total OHAP summation whenever the concentration for that individual chemical is 0.1 wt-% or more. Styrene and methylene chloride are currently suspected carcinogens and must be counted if present at 0.1 wt-% or more. MSDSs usually identify constituents that are, or may be, carcinogens. This information is provided in a separate section of the data sheet that discusses carcinogenicity or special toxic effects.

Composites manufacturers must keep copies of all air quality data sheets and MSDSs they use to document MACT compliance. In anticipation of the Aug. 23, 2004 compliance deadline for the boat manufacturing MACT, boatbuilders who use composites should immediately inventory all MSDSs and other data sheets to ensure that they have current OHAP content information for each resin and gel coat. If you are missing data sheets for some materials, obtain this information from the resin or gel coat supplier. Some resin and gel coat manufacturers have downloadable MSDSs or online MSDS request forms. Otherwise, call the manufacturer and request product data sheets. This also is a good time to ask any questions you may have concerning the OHAP content of the materials that you use.

Finally, to ensure that your compliance data is based on the latest available data sheets, two procedures should be in place. First, require your shipping and receiving department to pass copies of all newly received resin and gel coat data sheets to your plant's MACT compliance personnel. Second, conduct an annual (if not more frequent) audit to ensure that the data sheets used to demonstrate compliance reflect the current OHAP content of the resins and gel coats used at your plant.