Indoor air quality is one of the most integral components of wellness, at home and at the workplace.
Since we spend the majority of our time indoors, we need to be sure that we are breathing healthy air in our homes, offices, and schools. Interest in healthy buildings is spiking, and clean air is a key component.
One group of air pollutants we receive many questions about are VOCs, or volatile organic compounds. The sheer diversity within this group of indoor pollutants can be daunting, so we decided to tackle these tricky pollutants in this article.
Understanding VOCs: What You Need To Know About Volatile Organic Compounds
What Are VOCs?
Volatile organic compounds (VOCs) are a group of compounds with high vapor pressure and low water solubility. In other words, these substances won’t easily bind to themselves (volatile) or dissolve in water (organic). VOCs are emitted as gasses from everyday products such as building materials, maintenance equipment, and custodial products. Many VOCs are harmful to human health, especially over the long term.
Much like particulate matter, the term “VOC” doesn’t refer to a specific substance; instead, it refers to a group of substances that exhibit similar chemical properties. There are thousands of these substances, with some examples commonly found in buildings including:
- Benzene - found in tobacco smoke, paint thinner, deodorizers, air fresheners, furniture polish
- Formaldehyde - found in disinfectants, furniture upholstery, carpets, plywood
- Ethylene glycol - found in cleaning agents, personal care products, perfumes
- Methylene chloride - found in spot removers, dry cleaned clothes, fabric cleaners, commercial solvents, air conditioner refrigerant
- Tetrachloroethylene - used in solvents, dry cleaning, paint strippers
- Toluene - used in paint, metal cleaners, adhesives
When measuring the amount of VOCs in your home, you will often come across the term TVOC, or total volatile organic compounds. Just what does TVOC stand for?
What is TVOC?
Because there are so many VOCs, it’s impossible to monitor all of them continuously. Thus, a measurement known as TVOC was adopted to measure the overall amount of VOCs in a given space.
Total volatile organic compounds (TVOC) is a group of VOCs used to represent the entire pool of pollutants. If you have an air quality monitor that can detect volatile organic compounds, you will see your readings in terms of TVOC, represented as a single measure in parts per billion (ppb) or milligrams per cubic meter (mg/m3).
TVOC isn’t uniformly defined in terms of which VOCs are included in it. Many standards list different VOCs in their TVOC grouping or assign different weights when calculating TVOC. This can make some of the literature and discussions around TVOC difficult to parse since we can’t say definitively what VOCs are being referenced (unlike ozone or CO2, where we are measuring for the presence of a specific molecule).
Thus, when comparing TVOC levels across different measurement sites or projects, it’s important to first understand what is the exact definition or standard being used to derive the headline figure. Some broadly used standards for TVOC composition have been provided by the WHO, ISO, and Mølhave et al.
For more information on the unique challenge of defining TVOC, check out our article: Defining TVOC: Why TVOC Is So Difficult To Explain.
Where Do VOCs Come From?
Volatile organic compounds can come from an array of sources, including human-made and natural sources. Because manufacturers utilize VOCs as inorganic solvents, the majority of indoor VOCs come from everyday household and office staples, including:
- Paints and solvents
- Cleaners and disinfectants
- Air fresheners
VOCs aren’t only found in sprays and aerosols. Many products, such as glue, new furniture and carpets, construction materials, electronic devices, and plywood produce VOCs through off-gassing. New construction and renovation can present a significant health concern for this reason; until the off-gassing of new products declines, your indoor environment will trap these released VOCs and could harm occupants.
Household products are not the only source of VOCs; our own bodies produce VOCs as well. Often far less dangerous than industrial compounds, bioeffluents released by humans can trigger responses by our own bodies and others.
While many people think of VOCs as solely an indoor pollutant, outdoor VOC levels are also a concern, but for different reasons. Outdoor VOC levels, except for levels near industrial zones, are safe for us to breathe, but VOCs can contribute to other forms of pollution such as photochemical smog.
Are All VOCs Harmful?
Because of the sheer number of VOCs, it is natural to ask: are all VOCs harmful? The answer is that it depends - most compounds aren’t outright toxic, but some can still cause serious health complications after prolonged exposure.
Some VOCs are very harmful, like formaldehyde and benzene. These are present in glues and paints and are often found in cigarettes, vehicle emissions, appliances, cleaning products, furniture, carpeting, and personal products. We really need to watch out for these, as benzene is a known human carcinogen, and formaldehyde is a probable human carcinogen.
Other volatile organic compounds are far less harmful, often originating from natural sources. For example, plants use their own VOCs to interact with their environments, and these gases are by and large harmless to humans.
However, some studies show that even natural sources of VOCs, like human bioeffluents, can cause a higher cortisol response for a prolonged period of time. While there isn’t any research indicating that these cause long-term harm, we know that they can still cause a stress response to the body.
Because VOCs are a group of organic compounds that includes both natural and human-made carcinogenic pollutants, it is sometimes difficult to clearly determine if the source is harmful. In short, there are some harmful VOCs and some relatively harmless VOCs, but it is best to limit exposure to these gases.
How Can You Monitor VOCs?
Due to the abundance of VOCs and the many different everyday materials that can emit them, auditing every potential emitter in a residential or commercial building is usually not feasible. Instead, the best way to identify the presence of volatile organic compounds is by implementing air quality monitors and continuously tracking TVOC levels.
With an air quality monitor, you can spot trends in your TVOC readings and even discover potential sources of VOCs. For example, TVOC readings often increase sharply during office cleaning hours, as many cleaning materials emit VOCs. With an air quality monitor, you will know when it is best to increase ventilation to vent out VOCs and which products in your indoor environment contribute to dangerous TVOC levels.
For a technical deep dive on how air quality monitors detect VOCs and produce TVOC readings, check out How Does a TVOC Sensor Actually Work?
What Are Safe Levels of TVOC?
Once you’ve started collecting TVOC measurements, you’ll need a way to interpret the data and understand whether the measured levels are safe or indicate there is a problem with volatile organic compounds in your indoor environment.
TVOC measurements are provided in micrograms per cubic meter (ug/m3), milligrams per cubic meter of air (mg/m3), parts per million (ppm), or parts per billion (ppb). You can find various online explainers on how to convert these units.
In most guidelines, a concentration of less than 0.5 mg/m3 is deemed acceptable, along with a stipulation that any specific compound being tracked should not exceed 250 ug/m3.
While there is more than a bit of variance between different guidelines, the 500 ug/m3 repeats across different 3rd-party standards and can be seen as a good starting point. For example:
- In RESET, <500 ug/m3 is deemed acceptable, while <400 ug/m3 is considered high performance
- The WELL standard uses a baseline of <500 ug/m3, but WELL v2 focuses more on concentrations of specific VOCs that can be particularly harmful
- FItwel's Enhanced Indoor Air Quality Testing and Monitoring Protocol (PDF) also mentions levels of less than 500 ug/m3
TVOC Safety Levels Chart
What Are the Health Effects of VOCs?
As we discussed above, some VOCs are quite harmful, while others pose less of a threat. In general, some symptoms to look out for are:
- Eye, nose, and throat irritation
- Headaches and nausea
- Loss of coordination
- Allergic skin reactions
These all point to exposure to VOCs, and recognizing the signs can help alert you to their presence. Long-term exposure or exposure in large doses can be detrimental to our health, with volatile organic compounds capable of damaging our kidneys, liver, and nervous system, as well as causing cancer.
Furthermore, a more nebulous concern of indoor VOCs is sick building syndrome, or SBS. As a general term used to describe nonspecific symptoms that occur to occupants of a building, SBS is a relatively new medical condition closely tied to indoor TVOC levels. SBS cases can be mild or severe, and we aren’t yet sure of its exact causes.
What we do know, though, is that indoor air quality plays a critical role in developing sick building syndrome. So, to ensure occupant health, we need to ensure VOCs aren’t getting trapped in our homes or offices.
Actionable Methods To Protect Against VOCs
Because of the impact of VOCs on our bodies and on office air quality, we need to limit our exposure. But how do we do this?
Purchase safer alternatives
As with any pollutant, removing the source is the best way to eliminate volatile organic compounds from indoor environments. Many products nowadays have low-VOC versions available. Purchasing these safer alternatives will cut down the quantity of VOCs in your home or office, especially dangerous ones like benzene, formaldehyde, and methylene chloride.
Don't allow smoking indoors or near building openings
Along the same lines as the above recommendation, limit the amount of smoking in and around places where people live or work, to allow building occupants to breathe healthier air.
While smoking is banned inside the vast majority of commercial buildings, it’s important to ensure that outdoor smoking areas are sufficiently distanced from windows and entrances so that VOC-carrying smoke does not seep through these openings.
When it comes to private homes, preventive measures can still be taken to cut down on pollution from first or second-hand smoke. At the very least, open some windows to let the smoke out; this will not completely protect you and others, but it will cut down how much pollution is floating in your home.
Amp up ventilation (mechanical or natural)
One of the biggest reasons VOCs can build up indoors is because of a lack of ventilation. Volatile organic compounds are emitted directly into the indoor environment from everyday products, so they’ll get stuck inside unless they are diluted with fresh air or removed.
For commercial buildings, this can mean increasing the ventilation provided by HVAC systems when TVOC levels are higher, as well as regularly maintaining these systems to ensure they are working as expected. The use of carbon filters, which are designed to adsorb pollutants, is also recommended.
At home, increasing fresh air intake by opening windows will help release VOC-laden air and take in clean air, lowering the TVOC level in your home.
Use everyday products only as directed
Many products that contain volatile organic compounds carry safety warning labels and detailed instructions for use. It is crucial to follow these instructions, as mixing chemicals, storing them improperly, or utilizing them without proper safety precautions can be highly dangerous, or even deadly.
Before using any chemical products, such as cleaners, paint, paint strippers, or other solvents, carefully read all warning labels and directions and follow them strictly. In larger commercial buildings, ensure employees, custodial staff, and maintenance crews are doing the same.
Safe storage is indispensable
VOC off-gassing is often passive; you don’t even need to use the products for them to produce tremendous quantities of volatile organic compounds. For example, recently dry-cleaned clothing can produce perchloroethylene, a probable human carcinogen. Until the strong smell goes away, consider storing these clothes outside, or leaving them at the dry cleaners until the smell goes away.
In office buildings, typical VOC-emitters are adhesives, paint, cleaning agents, and materials used in construction. In order to reduce VOCs, office managers should work to safely store these materials in designated areas, restricting these areas so that tenants and occupants don’t regularly pass through them, and keeping a close eye on ventilation levels.
We hope you found our breakdown of volatile organic compounds (VOCs) useful! For more information about VOCs and how they fit into overall indoor air quality, sign up for our introduction to indoor air quality email series!