VOC stands for Volatile Organic Compounds. VOCs are chemical compounds that are carbon based and are in the form of vapor when at room temperature. In this case, organic is not a good thing, and indicates that these compounds do not occur naturally, but only as by-products of man-made substances.
Products and materials which contain volatile organic compounds release them as vapors through a process known as outgassing, which is lot like evaporation. The compounds are referred to as volatile because they are made of unstable molecules which are easily released into the atmosphere, particularly in environments of higher heat and humidity.
When inhaled or absorbed through tissue in other ways such as through the skin, even small amounts of these compounds can cause a wide range of undesirable symptoms. In prolonged and high levels of exposure, some VOCs can produce permanent damage to the kidney and liver, infertility, chronic respiratory infections and cancer. It sounds frightening, but surely we are protected against such dangers by environmental regulations and building codes? Unfortunately, many things around the home contain VOCs, including furniture, cosmetics, construction materials, cleaning supplies, pesticides, air fresheners, carpeting, paints and fuels.
Formaldehyde was one of the first VOCs to be discovered, in 1867, and owing to the long history of it’s use, has been researched and studied more than most other volatile organic compounds. The biggest source of formaldehyde in the home has been found to be outgassing from certain manufactured wood products, in particular medium-density fiberboard (MDF), particleboard used in flooring underlayment, and interior grade plywood. These material use urea-formaldehyde resins in the binding agent holding together wood fibers, laminations or particles.
Formadehyde vapors also are given off by fiberglass insulation, gypsum wallboard, carpet padding, drapes and curtains, synthetic upholstery materials, and resilient flooring; although they are not considered to be significant contributors to indoor air problems, under certain conditions they can raise VOC levels.
The other main threat of formaldehyde in the home is urea-formaldehyde foam insulation, which was used in the 1970’s, but has been banned for residential insulation use since the early 80’s, after widespread complaints of dizziness, nosebleeds, skin problems and vomiting from occupants. When purchasing a home, make sure that it does not contain this material. There is evidence that high levels of formaldehyde exposure can lead to cancer.
There have also been health studies done on other individual volatile organic compound releasing chemicals, although not as many. Following is a list of some of the more common known VOCs and their health effects.
Benzene– contained in paints, solvents and tobacco smoke, irritates the respiratory system and contributes to cancer.
Benzyl chloride– given off by vinyl tiles made with butyl benzyl phthalate, is an eye and respiratory system irritant, causes liver and kidney damage and is a central nervous system depressant.
Chlorobenzenes– in paints, stains and solvents cause liver, kidney and pulmonary damage, act as a narcotic
Ethyl benzene– in solvents, irritate eyes and respiratory system, a central nervous system depressant
Isopropanol– commonly known as rubbing alcohol, present in household cleaning products, is a central nervous system depressant
Methanol – commonly known as wood alcohol, is in adhesives, paints, solvents, dyes, wood finishes; causes central nervous system damage. When ingested, forms formaldehyde, leading to eventual blindness and death
Methylene chloride – also known as dichloromethane, is contained in paint removers, is a central nervous system depressant
Methyl ethyl ketone – in paints, solvents, wood finishes, nail polish remover and cleaning fluids, central nervous system depressant, irritates eyes and respiratory system
Para-dichlorobenzene – used in air fresheners and moth repellants, is eye and respiratory system irritant, cause of kidney, liver and central nervous system damage
Percloroethyene– used in dry cleaning, has been shown to cause cancer in animals
Petroleum distillates– in solvents, roofing and asphalt materials and solvents, central nervous system depressant and cause kidney, liver damage
4-phenylcyclohexene– used in carpet adhesives, irritates eyes and respiratory system, a central nervous system depressant
Polychlorinated biphenyls (PCB) – found in electrical components, a possible carcinogen
Sytrene – found in plastics, a possible carcinogen, central nervous system depressant, irritates eyes and respiratory system
Tolulene – found in adhesives, solvents, vinyl floors, paints, caulking, drywall joint compound and tobacco smoke, linked to anemia, is a narcotic
Tricloroethylene– in dry cleaning supplies and solvents, a possible carcinogen, causes central nervous system
Xylene – contained in adhesives, solvents, drywall joint compound, floor finishes tobacco smoke and dyes, irritates eyes and respiratory system, is a central nervous system depressant, causes kidney, liver and heart damage
Testing and Remediation
VOC emissions present in a home are usually of various types and difficult to analyze. If someone in the home is having symptoms and you suspect VOCs may be to blame, it is best to call in local health authorities for a home inspection as a first step. They will look for known sources of VOCs and ask questions about your home and it’s contents. There are home screening kits and devices available to measure total volatile organic compound (TVOC) levels, but they are not of much use, so don’t waste time and money on them.
There are also devices for homeowners to test formaldehyde levels which are more reliable, if you suspect this compound in particular. The best way to monitor formaldehyde levels is to use DNPH badges. These are absorbent test badges containing 2,4-dinitrophenyl-hydrazine, which are hung from the ceiling at breathing level. After a 1 to 4 hour exposure to the household air, the badge is sent to a lab for analysis. In the U.S., OSHA has adopted a Permissible Exposure Level of .75 parts per million (ppm) for fomaldehyde, and an action level of 0.5 ppm. Current information indicates that it is advisable to mitigate formaldehyde exposure in the home if it is at levels higher than 0.1 ppm.
Getting rid of high levels of VOCs in the home involves removing the product that gives off the volatile organic compound. Most products containing VOCs will off-gas within a short period of time, although some will continue to give off VOCs for longer periods of time. Ventilation and climate control can also be used to reduce exposure to VOCs. Open doors and windows as much as possible, use fans, and maximize air brought from the outdoors. Since chemicals offgas more in warmer conditions with high humidity, keep the temperature and relative humidity as low as comfortable.
Levels of formaldehyde out-gassing are at their highest in new products such as cabinetry in the first six months after installation and typically drop by 50% after one year, then by another 50% after four years. Since out-gassing will continue at lower levels until all formaldehyde in the materials have been released, one way to lower levels of this VOC in the home is to apply a VOC-free sealer on them, such as water-based polyurethanes or lacquers.
Avoidance is the best remediation, although this can be difficult and costly, since VOCs are so widely present. When doing home renovation and improvement projects, care should be taken to use only solvents, paints caulks, adhesives and finishes with low levels of VOCs, and if available, VOC-free versions. With particleboard and plywood, look for grading stamps indicating formaldehyde levels are within specified federal limits.
Photo by Ms..G, Creative Commons Attribution