Q & A with an Indoor Air Quality Professional: Volatile Organic Compound (VOC)
V-O what? Volatile Organic Compound (VOC) , what are they and why are they an indicator of healthy indoor air quality? Hello and welcome! This post is one in a series called “Q & A with IAQ professionals” where we interview seasoned professionals in the indoor air quality field about various specialties. For this installment, we will be discussing the topic of Volatile Organic Compound (VOC).
Randy Penn with Envirochex, a Dallas air quality consultant, has agreed to share some of his knowledge with us on the topic by answering a few questions on the subject. With over 37 years of experience in engineering & construction and one of the authors of “Comparison of Metrics for Characterizing the Quality of Indoor Air” for ISIAQ IndoorAir2011, it is safe to say Randy knows his stuff. Now let’s get started.
Moldlab asks:
What are VOC’s and where do they come from?
Randy answers: VOC’s are volatile organic compounds – a very broad group of carbon-based chemicals (organic) that easily vaporize at room temperatures (volatile). They are emitted from a wide range of building materials & finishes, furnishings, cleaning/maintenance products, personal care products, combustion sources, and occupancy activities.
2. How common is it to have VOC’s present?
Randy answers: Virtually all indoor air has VOC’s at some concentration level depending on ventilation rates. And in tightly built structures without ventilation, levels are often elevated. We commonly see air in these structures as a mixture with 20-50 individual chemicals when tested in the parts-per-billion (ppb) range.
3. What are a few indicators that someone might have a Volatile Organic Compound (VOC) problem in their home or place of work?
Randy answers: All odors are chemicals so the first indication might be at your nose; however, not all chemicals or levels present produce detectable odors so you may not notice them by smell alone. Other examples of exposure symptoms include eye, nose, and throat irritation, headache, nausea, fatigue, dizziness, etc. People may experience sensitivity to a single chemical, a mixture of two or more, or the sum total of all (commonly referred to as a total volatile organic compound level or TVOC).
4. What are some key issues professionals consider when selecting a VOC test method?
Randy answers: One of the most critical considerations is the measurement range and limit of detection of the method selected. Methods limited to 1 part-per-million (ppm) will not reveal conditions we see using 1 part-per-billion (ppb) techniques which are a thousand times more sensitive. Think of how much more you’ll see using a 1000X microscope instead of the naked eye.
Another challenge is to select methods for the types of compounds you are interested in since there is no single test which will identify everything. Many standard VOC methods have limited lists of compounds or exclude key groups like aldehydes.
5. What are some common testing methods?
Randy answers: Hand-held meters are available that report TVOC levels; however, they typically don’t quantify all constituent chemicals of the mixture. Similarly there are meters that can quantify specific chemicals if you know them in advance.
To get to a full breakdown, specimens collected in the field must be sent to an analytical laboratory and there are two predominant methods: a) collecting a specimen of the air containing the chemicals using specialized equipment (i.e. canister); or b) collecting a specimen of the chemicals from the air using sorbent devices.
6. Why do some test kits specify Volatile Organic Compound (VOC) and Formaldehyde separately?
Randy answers: Primarily because formaldehyde can be difficult to retain on general sorbents and the lab analysis requires different analytical methods.
7. What is the difference between a VOC and a MVOC?
Randy answers: MVOC is a descriptor often used to describe VOC’s produced by microbial organisms. Examples include constituent compounds that yield the musty odor of molds or pungent odor of sweat socks.
8. Have regulating institutions like the EPA, NIOSH or OSHA determined permissible exposure limits (PEL) for VOCs?
Randy Answers: In general terms, EPA’s regulates outdoor air with NIOSH and OSHA focusing on occupational settings with defined exposure times (e.g. a standard work shift). There are currently no mandatory standards and very few guidelines for non-occupational indoor air where low-levels and long-term exposures are key factors. Furthermore, studies have shown mixtures of chemicals appear more significant than individual compounds.
9. What are 3 things people can do in their own homes/offices to reduce possible exposure to VOCs?
Randy Answers:
Source control is preferred – eliminate the substance or use materials with lower content (e.g. Low-VOC paint).
Secondly, reduce levels by diluting with outdoor air – automatic ventilation systems are available and recommended.
Lastly, some VOC’s may be reduced through capture or converted in an air cleaning device (unfortunately, no single technology has shown to be 100% effective on every compound or mixture and some have unintended consequences).
Sources of Volatile Organic Compounds
Thank you very much for you time Randy, we really appreciate it. Oh and if anyone calls and reports the smell of ‘sweaty socks’ I’ll be ready! And yes the kitty picture to the right is silly, but was too cute and I couldn’t resist posting it.
If your organization is interested in a lecture or presentation on IAQ topics like Mold or VOCs, Randy Penn can be reached at (214) 236-5047. Envirochex consulting company is also available for on site investigations and evaluations.
We know VOC’s is a big topic to tackle and hope to publish more on the subject in the future.
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