1. Volatile organic compounds (VOCs) are carbon compounds that participate in atmospheric photochemical reactions (excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides and carbonates, and ammonium carbonate). The compounds vaporize (become a gas) at normal room temperatures.2. A molecule containing one or more carbon atoms that tends to evaporate (volatilize) into the air at typical ambient conditions. Some legal definitions of VOCs are restricted to those that react with sunlight to generate smog. Some VOCs are carcinogens, suspected carcinogens, or known irritants at typical levels.