What are Volatile Organic Compound?
The U.S. Environmental Protection Agency defines volatile organic compounds (VOCs) as “organic chemical compounds whose composition makes it possible for them to evaporate under normal indoor atmospheric conditions of temperature and pressure.” The term applies to any organic compound that boils at or below 250° C at standard atmospheric pressure. VOCs are usually released into the air from materials containing these compounds. This covers a wide range of materials that we have discussed in previous articles. The World Health Organization classifies VOCs as very volatile, volatile and semi-volatile.
The concern with VOCs is that some may constitute a long-term health threat and/or contribute to smog formation. This, along with the relative ease of application and cleanup, has caused a large shift to latex- and aqueous- based paints and coatings, which usually have fewer VOCs. However, this alternative is not available for some applications.
The Role of OSHA
In the workplace, the Occupational Safety and Health Administration (OSHA) regulates VOC exposure. One way it does this is to require manufacturers to produce Material Safety Data Sheets that list ingredients and disclose many important facts, including the concentration of VOCs, usually in grams per liter. It is important to note that even if a product has no VOCs, acute contact or chronic inhalation might cause physical damage, and the MSDS will point this out under the Health Hazard Data section. For example, Dur-A-Flex Poly-Crete Colorfast Hardener, a product we’ve recently discussed, is chiefly composed of hexamethylene diisocyanate (HDI). The MSDS for this product lists zero VOCs but also contains a warning against prolonged contact.
Examples
Here are some of the products we’ve discussed in recent blogs:
- Dur-A-Flex Armor Top: this is a three-part aliphatic urethane system containing a resin (blocked cycloaliphatic diamine), a hardener (HDI), and a colorant (dipropylene glycol monomethyl ether acetate + coloring oxides). Only the colorant has VOCs. On its own, the VOC concentration is 572 g/l, but when mixed with the other parts, the VOCs decline to between 95 and 82 g/l.
- POR-15 Rust Preventative Coating: a blend of:
- Polymers of ethylene oxide, propanol and isocyanic acid
- Naphtha
- Aluminum/titanium oxide/carbon black, depending on color
- Methylene bisphenyl isocyanate
The VOCs in this product vary from 270 g/l to 333 g/l, depending upon color and gloss. Some of the ingredients are skin irritants, but California and Minnesota list carbon black as a known carcinogen.
- Dur-A-Lac Novolac Resin: contains diglycidyl ether bisphenol a epoxy resin, and has no VOCs, although exposure could result in skin irritation and dermatitis.
- Fox Industries FX-501M Elastomeric Coating: although waterbased, this acrylic polymer contains diphenyl ketone, ethylene glycol and coloring agents. Its MSDS lists VOCs at 71 g/l.
- Hi-Temp 1027: this is a paint/primer containing a heady brew of naphthalene, heavy aromatic naphtha, xylene, toluene, ethylbenzene and dimethyl carbonate. It has a whopping VOC of 420,000 g/l and is 24.49 percent volatile by weight. The MSDS recommends use of suitable respiratory equipment when ventilation is insufficient.