Volatile Organic Compound Panels (BTEX)

Volatile organic compounds (VOCs) are organic chemical compounds which have high vapor pressure at normal room temperature and pressure.  It is this high vapor pressure trait which add the moniker of ‘volatile’ since these chemicals will outgas or evaporate from the products containing them.   In addition to their high vapor pressure, VOCs also have low water solubility meaning that they can persist as ground-water contaminants.  The term ‘VOC’ is used for both indoor and outdoor air quality, but, the term and what is regulated slightly differs in each of these areas. 

In the outdoor environment, the primary focus is to limit the formation of ozone which is formed when some VOCs react with oxygen molecules and sunlight.  In an industrial setting, VOCs are used as industrial solvents, fuel oxygenates, and may be produced as by-products of chlorination for water treatment in the case of chloroform.  VOCs are generated during petroleum refining, metal production, chemical processing, and product manufacturing.  In this context, only certain VOCs are of concern, however, these may still be of concern in an indoor environment.  

Within the indoor environment, VOCs exist in many products used in home construction and maintenance.  These products include such things as paint, varnishes, solvents, preservatives, aerosols, cleaners, fuels, glues, air fresheners, and pesticides.  Other sources may include carpet, building materials, furnishings, and even dry-cleaned clothes. 

Exposure to VOCs may result in both short- and long-term health effects such as eye and respiratory irritation, headaches, loss of coordination, nausea, liver damage, kidney damage, central nervous system damage, and cancer.  While most VOCs are not acutely toxic, VOCs health effects from long term exposure can vary greatly from some that are highly toxic to others with no known health effect.  The extent and nature of the health effects will depend on the level of exposure, timeframe of exposure, and the specific VOC.

In an industrial setting, monitoring of any VOC release is important to protect worker health.  The VOC type and release level can vary depending on the process itself and any abatement processes in place.  These processes to limit VOCs often utilize heat which destroys harmful chemicals.

Yet another concern may arise with the association of VOCs to sick building syndrome, or SBS.  This term has been used to describe instances where nonspecific symptoms have been found in occupants of a building.  The difficulty is that the term SBS is vague and difficult to trace to the exact cause.

Within the home, exposures can occur due to outgassing of contaminated products, improper storage, or poor ventilation.  VOC levels indoors average 2 to 5 times higher than outdoors with this easily spiking 1000-fold following certain activities such as paint stripping.  To reduce exposure, it is important to increase ventilation when using VOC containing products.  If possible, storage of any VOC containing products should be outside the home in a shed or in a well-ventilated area as sealed containers may still release vapors. 

Given the large number of sources, it should come as no surprise that there exist thousands of organic (carbon-containing) chemicals which are gasses at room temperature.  While it would be impossible to monitor all VOCs, often a representative sample of VOCs is selected and may be referred to as testing for total volatile organic compounds (TVOC).  While this term is not standardized, the test may provide insight when attempting to isolate the source of a VOC issue. 

The most commonly measured VOCs are a group known as BTEX which includes Benzene, Toluene, Ethylbenzene, and Xylene.  This group has provided a straightforward way to monitor and provide a well-rounded picture of VOCs present in most urban areas.  Benzene levels tend to be tightly associated with vehicle exhaust and the burning of solid and liquid fuels.  And while the other 3 components are also found in these sources, they are most commonly found when released from industrial facilities.  Thus, BTEX monitoring is routinely carried out as ‘fence line monitoring’ to ensure industries are not releasing VOCs which are affecting the surrounding communities.