Volatile organic compounds, or VOCs, sometimes also called polycyclic aromatic hydrocarbons, are chemicals made of hydrogen and carbon that vaporize at room temperature. This process, known as off-gassing, releases harmful chemicals into the air. And because these chemicals are found in a wide range of consumer products, they can have a considerable effect on indoor air quality.
Because volatile organic compounds can pose risks to health and environmental protection, various regulatory bodies have published standards and guidelines to establish what healthy VOC concentrations are and how to prevent excessive exposure.
Understanding the different volatile compounds
VOCs are generally divided into three groups. They are:
- Very volatile organic compounds (VVOCs)
- Volatile organic compounds (VOCs)
- Semi-volatile organic compounds (SVOCs)
VOCs are classified according to their volatility, a complex chemical term used to describe how easily these substances change state. The boiling point range is used to help classify VOCs and determine which are very volatile and which are semi-volatile organic compounds.
However, just because SVOCs are less likely to vaporize does not mean they are less dangerous. It is important to know some of the most common SVOCs and where they come from in order to help limit exposure and the health problems they can cause.
One common source is pesticides, but these chemicals can be found in many other places, which calls for constant vigilance to avoid overexposure.
The different semi-volatile organic compounds
Benzoic acid
Named after gum benzoin, which was long considered its only source, this chemical is found in everything from food preservatives (labeled E210, E211, E212, etc.) to plastics. It is mainly used in the initial formation of carbon polymers that will eventually be used to make plastic.
Benzyl alcohol
Used as a general solvent for inks, waxes, shellac, paints and varnishes, this SVOC is one of the most common. It is also used in the manufacture of nanowires, and it has been approved (when diluted to a 5% solution) as a treatment for head lice. It essentially suffocates the parasites and kills them before the infestation spreads too far.
Benzyl phthalate
Also sometimes called bromophenyl phenyl, benzyl butyl phthalate, or simply butyl benzyl, this is probably one of the most common SVOCs today. Its main application is as a plasticizer, typically in the production of vinyl foams (used in floor tiles), as well as in other durable yet flexible plastics, such as those used in traffic cones, conveyor belts and artificial leather.
Chlorophenyl phenyl
A variant of benzene, this chemical is often hard to pin down within the composition of other compounds, but it is one of the most common VOCs you can find. It is mainly released by the combustion of coal and oil, as well as by the evaporation of gasoline. It ranks among the 20 most common chemicals in use today. And although concentrations in a given area tend to be low, gas leaks or fires can drive airborne concentrations up to dangerous levels.
Organochlorine pesticides
Pesticides have been widely used for half a century, and they are almost indispensable in modern large-scale agriculture. However, many of these substances, such as organochlorine pesticides, known in the industry as DDT, cause serious health and environmental problems, which has led to their being banned directly or indirectly in many countries around the world.
However, just because organochlorine pesticides are strictly controlled does not mean VOCs are absent from food and water extracted on a large scale. It is therefore still important to look into where food comes from to make sure no dangerous chemicals were used in its production.
Flame retardants
Another major source of SVOCs is flame retardants. Polychlorinated biphenyls (PCBs or PBBs) are the chemicals most commonly used in fire extinguishers and other devices designed to put out flames. Although these chemicals only escape into the air when these devices are used, it is important to thoroughly ventilate the area where they were discharged.
Avoiding SVOCs
It is impossible to avoid exposure to VOCs completely. They are found in many popular products, and because they vaporize at room temperature, it is almost impossible to control their release into the air. However, knowing the sources of VOCs and the relevant safety standards will help ensure good indoor air quality, thereby reducing the risk of health problems linked to these chemicals.
For more information on indoor air quality, check out these resources:
- Air pollution particle size. If you care about your environmental health, it is important to know that volatile organic compounds are only one part of the equation. Particulate matter is the other part. These particles are surprisingly small, which makes it hard to know when they pose a health risk.
- How to reduce particulate pollution. Protection against these harmful chemicals starts with limiting exposure and creating the best possible air conditions.
- Indoor air quality guidelines. An excellent resource for those looking for more information on volatile organic compounds and how to limit their presence in the home.