If you're researching or discussing indoor air quality, chances are you'll read and hear a lot about VOCs. What are they, exactly, and where do they come from? Do they affect indoor air quality? Are they harmful? This article will help answer some of those questions.
In order for a chemical to be classified as a VOC, it must meet 2 basic criteria - it needs to be classified as an organic chemical and it must exist as a vapor at room temperature. The acronym TVOC stands for total volatile organic compounds, or the sum of all the VOCs in a space. While VOCs and TVOCs are technically different, the terms are often used interchangeably.
How do VOCs get into an indoor air environment? Many times they are emitted from items that are in indoor spaces in either solid or liquid form. Paints and varnishes, building materials, furniture and carpeting, household cleaners, cigarette smoke, and even personal care products emit VOCs. The complete list of VOC-emitting products and materials would have hundreds more items on it.
VOCs can also get indoors by way of contaminated soil or groundwater under a building. If VOCs are present in these media they can migrate into a building through cracks in the foundation, basement floor, sewer lines, or any penetration that compromises the barrier between the building and the surrounding soil. This phenomenon is called vapor intrusion.
There are thousands of VOCs. They can be naturally-occurring or synthetic. Some are highly toxic, others are moderately toxic, and still others are mildly toxic. Each VOC or class of VOCs has its own set of potential negative health effects. Many of the common VOCs have been well studied. In these cases their toxic properties are understood and exposure limits or guidelines have often been established. Formaldehyde, perchloroethylene, benzene, and xylene fall in this group. Unfortunately, many VOCs have yet to be evaluated for their potential to harm workers or other building inhabitants.
VOCs can negatively impact indoor air quality if they are present in concentrations that will cause building inhabitants to experience medical signs and symptoms or become sick. Complaints of eye, skin, and throat irritation, headache, nausea, and fatigue are common in buildings with elevated levels of VOCs.
Are indoor air VOCs harmful? Here's where things get tricky, as it depends on the specific VOC in question, the concentration of that VOC, and the toxic properties of that VOC. If you know the specific VOC involved and if that VOC has an exposure limit, air monitoring can be performed and the results can then be compared to the corresponding exposure limit. Concentrations above the exposure limit will increase the risk of adverse health effects.
If you suspect that VOCs are impacting your indoor air quality but don't know which VOCs are responsible you can obtain a representative grab sample of the air and request a VOC analysis to identify the culprits. Like the scenario described above, the VOC concentrations can then be compared to the exposure limits.
Sometimes it's difficult to identify the offending VOCs - or they are identified but don't have exposure limits. In these situations you can use a real-time monitor to screen the space for TVOCs. If VOCs are present, an overall concentration will be reported. While there are no exposure limits for TVOCs some guidelines have been recommended. Generally, TVOC concentrations between 50 parts per billion (ppb) and 325 ppb are thought to be acceptable. Similarly, it's often recommended that indoor air TVOC concentrations not exceed 500 ppb. More in-depth evaluations and investigations should be performed if TVOC concentrations exceed this value.
It makes good sense to keep all indoor air VOC concentrations as low as reasonably achievable. Thorough investigations which focus on identifying the source of VOCs and reducing VOC concentrations are crucial. Certified Industrial Hygienists have the training to perform these investigations and navigate through the uncertainties of unknown VOCs and the lack of exposure limits. They can assess the building in order to identify which items are contributing to the indoor air VOC load. Likewise, they can recommend measures which will eliminate, reduce, or control VOC concentrations and reduce the risk of adverse health effects.
Do you have indoor air quality concerns? Do you suspect VOCs or other agents are to blame? Click on the link below to obtain more information on how Cashins & Associates can help!