Volatile Organic Compounds (VOCs) are a large group of carbon-containing chemicals that readily vaporize at room temperature, becoming gases in the air. Emitted from various solids and liquids, VOC concentrations are consistently and significantly higher indoors—often found at levels two to ten times greater than those measured outside. This is due to the sheer number of products and materials used in modern homes that release these gases into confined spaces. Understanding the specific sources of these airborne chemicals is the first step in addressing indoor air quality and mitigating potential exposure.
Sources from Building Materials and Furnishings
Many VOC sources are permanent fixtures built into a home’s structure, leading to chronic, long-term emissions. The process by which these chemicals are continually released into the air is known as “off-gassing.” This off-gassing is particularly pronounced when materials are new, but it can persist for months or even years after installation.
Adhesives and sealants used in construction are major contributors, alongside paints and varnishes applied to walls and trim. Traditional oil-based paints and certain high-VOC latex paints release chemical solvents like toluene and xylene, which can linger long after the paint seems dry. Pressed wood products, such as plywood, particleboard, and medium-density fiberboard (MDF), are also significant sources. They contain formaldehyde-based resins and glues, making formaldehyde one of the most commonly emitted VOCs found in new furniture and cabinetry.
Flooring materials also release VOCs, including the adhesives used to lay down vinyl, laminate, and new carpeting. New carpets, for instance, can off-gas from their synthetic fibers, backing materials, and the glues used during installation. The rate of off-gassing tends to increase when temperatures and humidity levels are higher. Other furnishings, like upholstered furniture and mattresses made with polyurethane or memory foam, also emit VOCs like benzene, contributing to the overall chemical load in a room.
Sources from Consumer Products and Household Activities
Consumer products and daily activities introduce a second major category of VOCs, often resulting in high, short-term spikes in indoor air levels. Cleaning supplies are a prime example, with products like disinfectants, degreasers, and even common glass cleaners releasing compounds like ethanol, acetone, and terpenes. These chemicals are released immediately upon use and can maintain elevated concentrations in the air long after the cleaning task is finished.
Aerosol products, including air fresheners, hairsprays, and certain furniture polishes, contribute substantially to VOC levels, often using volatile solvents to atomize the product. Many fragranced products, such as plug-in air fresheners and scented candles, release terpenes like d-limonene and alpha-pinene. Hobby and craft supplies, such as glues, permanent markers, graphic materials, and specific craft paints, also contain various solvents that vaporize quickly into the indoor air.
Certain household activities and stored items represent intermittent but concentrated sources of VOCs. Stored fuels, such as gasoline and oil, along with automotive products kept in an attached garage, can release VOCs that seep into the main living space. Dry-cleaned clothing carries residues of chemicals like perchloroethylene, which is widely used in the dry-cleaning process and slowly off-gasses into the home environment. Combustion activities, including tobacco smoking, cooking, and burning wood in a fireplace, also release a variety of VOCs into the indoor air.
Understanding the Health Implications of Exposure
The presence of VOCs in indoor air is a concern because exposure can result in a range of adverse health effects. The severity of the effects depends on the specific VOC, its concentration, and the duration of the exposure. Short-term, or acute, exposure to high levels of VOCs can trigger immediate symptoms.
Common acute effects often involve irritation of the eyes, nose, and throat, as well as headaches, dizziness, and nausea. People with pre-existing conditions, such as asthma, may experience a worsening of their respiratory symptoms when exposed to elevated VOC concentrations. Long-term, or chronic, exposure to low levels of certain VOCs is linked to more serious health risks.
Extended exposure has been associated with damage to the liver, kidneys, and central nervous system. Specific VOCs, such as formaldehyde and benzene, are identified as known or suspected carcinogens, raising concerns about the potential for increased cancer risk over a lifetime of exposure. Identifying and reducing the sources of these pervasive indoor pollutants is a significant public health consideration.
Practical Steps for Reducing Indoor VOC Levels
The most effective strategy for reducing indoor VOC levels is to control the source of the emissions. When purchasing new items, consumers can choose products that are labeled as “low-VOC” or “VOC-free,” which is now common for paints, adhesives, and building materials. For new furniture, mattresses, or other large items that are known to off-gas, it is helpful to allow them to air out in a well-ventilated space, such as a garage or porch, before bringing them indoors.
Improving ventilation is another effective measure for diluting and removing VOCs from the air. Opening windows regularly to increase the exchange of fresh outdoor air helps lower the concentration of pollutants that have accumulated inside. It is particularly beneficial to increase airflow when engaging in high-VOC activities, such as painting, using strong cleaning products, or undertaking home renovations.
Proper storage and disposal of high-VOC products also minimizes their release into the living space. Unused paints, solvents, and cleaning chemicals should be kept tightly sealed in their original containers and stored in a detached shed or garage, away from the main occupied areas of the home. Reducing the use of fragranced products and opting for non-toxic cleaning alternatives, such as simple vinegar and baking soda solutions, can significantly decrease the introduction of new VOCs.