Chemistry and Chemical Disasters. Volatile Organic Compounds (VOC's) are organic chemicals that have a high vapor pressure and easily form vapors at normal temperature and pressure. The term is generally applied to organic solvents, certain paint additives, aerosol spray can propellants, fuels (such as gasoline, and kerosene), petroleum distillates, dry cleaning products and many other industrial and consumer products ranging from office supplies to building materials. VOC's are also naturally emitted by a number of plants and trees. TVOC stands for Total VOC's and is the concentration of all VOC's in a given sample (there may be several different VOC's present in a sample). A VOC number, VOC rating, or VOC contentexpresses the amount of volatile material in a sample, either in pounds per gallon, grams perliter or as a percentage by mass. Additional Info: VOC's are an important health and environmental concern for several reasons: (1) Some VOC's can be hazardous to your health wheninhaled. For example, benzene is a probable human carcinogen and toxic. Likewise, formaldehyde is both an irritant and a sensitizer. Many VOC's are flammable. (2) VOC's from outgassing of fabrics, building materials etc. are an important contributor to sick building syndrome (SBS). For more on SBS See: Further Reading below. (3) VOC's such as hydrocarbon (gasoline, petroleum distillates) emissions from cars and trees are important contributors to photochemical smog. (4) Some VOC's such as methyl tert-butyl ether (MTBE, once added to gasoline to make it burn more cleanly) have a fair solubility and rather high mobility in groundwater, leading to the contamination of drinking water wells. VOC's can be removed with special filtration systems. For example, activated charcoal absorbs many organic materials, but it has a limited capacity, is not an indicating adsorbent (so you won't know when it has reached its limit) and does not adsorb all materials. MSDS Relevance: Minimize or eliminate the use of VOC's whenever possible (see item #2 under Further Reading below). If you must use a VOC, minimize your exposure by using proper engineering controls such as a fume hood or other form of local exhaust ventilation. Gloves, a respirator and/or other appropriate personal protective equipment may also be necessary if the hazard can not otherwise be reduced to acceptable levels. Whenever using a flammable material use adequate ventilation and remember thatvapors may travel large distances. Heavier-than-air vapors (as most organic vapors are) can "pool" in low-lying areas, leading to an explosion when ignited by a flame, spark or static electricity. There are several reports each year of people blowing up their basements and themselves when using floor sealers etc. in a basement where the furnace or hot water heater pilot light ignited VOC's that had reached theirlower explosive limit. See also: Engineering Controls, Flash Point, Flammable Limits, Fume Hood, NFPA, Ventilation