What are VOCs? The facts about volatile organic compounds

Volatile organic compounds (VOCs) are a diverse group of gaseous chemicals emitted from various household and natural sources. They are often responsible for the characteristic smells of perfumes, cosmetics and things like paint thinners and cleaning solutions. Frequent exposure to certain VOCs is associated with adverse health effects such as respiratory irritation, nausea and even cancer.

VOCs have high vapor pressure, meaning they are relatively unstable at room temperature, and if not contained, will float into the air in their gaseous state. They also do not dissolve in water very well, if at all. VOCs are commonly used as chemical solvents (something that dissolves other chemicals), according to the U.S. Environmental Protection Agency (EPA).

VOCs are typically very small molecules. "They are detectable by spectroscopic methods of a particular concentration," Rigoberto Advincula, a researcher in chemical and biomolecular engineering at the University of Tennessee, told Live Science by email. This means that the concentration of these chemicals in the air is measured based on how much light they absorb at a specific wavelength.

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The amount of VOCs in the air is then defined in parts per million (ppm), which is a weight-to-weight ratio with other airborne particles.

• Related: The five states of matter: Definition and phases of change

Where do VOCs come from?

Some VOCs are naturally produced by animals, plants and microorganisms, in which case they are more specifically called biogenic volatile organic compounds (BVOCs). The most prominent BVOCs are isoprene and monoterpenes, both of which are produced by plants, according to an analysis published September 2014 in the journal Atmospheric Chemistry and Physics.

Plants produce about 90% of all VOCs in the atmosphere, and these chemicals play an important role in the chemical processes that occur in the environment. For example, the VOCs released by a rainforest keep the atmosphere above it clean and chemically balanced by reacting with harmful pollutants in the air, but this does not happen in areas devoid of plant life, according to a study published April 2008 in the journal Nature.

However, climate change may impact how and where VOCs are released into the atmosphere, according to a study published November 2020 in the journal Proceedings of the National Academy of Sciences of the United States of America.

About 10% of VOCs in the environment are human-made. Common sources include petroleum fuels, hydraulic fluids, paint thinners and dry-cleaning chemicals, according to the EPA. VOCs are also found in many common household and office items, such as building materials, cleaning solutions, cosmetics, permanent markers, adhesives, printers and copiers.

"The most common indoor VOCs include formaldehyde, benzene, acetone, toluene, xylene, and naphthalene, to name a few," Shahir Masri, an associate specialist in air pollution exposure assessment and epidemiology at UC Irvine Joe C. Wen School of Population & Public Health, told Live Science by email.

The concentration of VOCs is usually two to five times higher inside homes than outside, and it can be up to 10 times higher in some cases, according to the EPA. Researchers with the EPA have also found that some VOCs can remain in indoor air for several hours, at levels up to 1,000 times background levels outdoors.

Are VOCs dangerous?

The danger of VOCs to human health varies greatly depending on the specific chemical and exposure level. Some people, such as children or those with respiratory conditions, may also be more prone to adverse reactions than others, according to a review published July 2022 in the International Journal of Environmental Research and Public Health.

Nonetheless, many VOCs can cause health problems, especially if a person is exposed to high levels, or even low levels for a long time. "The frequency and severity of exposure matters and higher exposures will typically produce worse symptoms," Masri said.

Symptoms of high, short-term exposure to VOCs include eye, nose and throat irritation, headaches, nausea or vomiting, dizziness, and worsening of asthma and allergy symptoms. Exposure to these chemicals for many years at high or even low levels can lead to cancer, organ damage and poor reproductive health.

"Formaldehyde, for instance, is a widely known human carcinogen, and this compound is often emitted from the cheap compressed wood that makes up many furniture pieces," Masri said.

Benzene — a common VOC found in cigarette smoke, fuels and paints — has also been shown to increase the risk of cancer. According to a review published June 2018 in the journal Critical Reviews in Toxicology, long-term exposure to benzene vastly contributes to blood and bone marrow abnormalities and may cause conditions such as leukemia and non-Hodgkin lymphoma (a cancer of the lymphatic system).

Another commonly encountered harmful VOC is perchloroethylene, which is widely used for dry cleaning. Studies have found that people breathe in perchloroethylene when around or wearing dry-cleaned clothing, according to the EPA. Many dry cleaning businesses remove as much of the chemical as possible from the clothing, but if the clean clothing has an odor when it's picked up, then it still has perchloroethylene on it.

Other common VOCs found in households, such as gasoline or fluorinated ingredients including PFAS, can be tolerable at lower ppm, but they still can be toxic, according to Advincula. "Over time, they can accumulate in the lungs and disrupt hormonal balance,” he said.

It is difficult to pinpoint which VOC-emitting household products have the highest health risk because studies generally examine the toxicity of a single chemical, rather than the combinations of chemicals typically found in household products. But the frequency and type of use can definitely impact the level of health risk these chemicals represent in a home.

Details about the known health effects of specific VOCs can be found in the Centers for Disease Control and Prevention's toxic substances database.

How to remove VOCs from your home

There are no federal or state standards for healthy VOC limits in non-industrial areas, so if you suspect VOCs may be causing health issues for you or others in your household, the Minnesota Department of Health recommends removing as many VOC-containing products as possible from the home.

Also, store VOC-emitting products in an area people don't frequent, such as a storage shed or garage. Increasing your home's ventilation and keeping the home cool can also help, as materials release VOCs more in warm temperatures and stagnant air will hold VOCs for longer. Air purifiers can also help remove VOCs, Advincula said. However, they need to be equipped with carbon or activated carbon filters.

While many of the best air purifiers on the market come with High-Efficiency Particulate Air (HEPA) filters that are capable of trapping over 99.97% airborne particles as small as 0.3 microns, these are not capable of trapping such tiny particles as VOCs. Activated carbon filters, on the other hand, can handle such a task. "However, these filters need to be regularly replaced [to maintain their effectiveness]," Advincula cautioned.

This article is for informational purposes only and is not meant to offer medical advice.