Outgassing is the process where a manufactured material releases trapped gases into the surrounding air over time. This release is sometimes called offgassing, particularly when discussing indoor air quality and consumer products. The phenomenon occurs because chemicals used during manufacturing, such as solvents, binders, and additives, become absorbed or dissolved within the material’s structure. Materials stabilize after production or when exposed to new conditions, causing these absorbed compounds to escape into the environment.
The Physics of Gas Release
Diffusion is the movement of gas molecules from high concentration within the material’s bulk to the lower concentration of the surrounding air. This molecular movement is continuous, although the rate of release slows down as the concentration of trapped gas decreases over time.
Gases also become trapped within the material matrix through adsorption, where molecules adhere to the surface, and permeation, where they pass through the material barrier. Elevated temperatures significantly accelerate the release rate, as heat provides the energy needed for molecules to move more quickly and escape the material.
The material’s composition, such as its porosity and chemical structure, determines the total amount of gas trapped and the speed of its release. For instance, polymers, foams, and adhesives trap a greater variety of chemicals than simpler materials. While the initial burst is the most noticeable, a low level of outgassing can continue for months or even years.
Everyday Sources of Outgassing
Outgassing is responsible for the characteristic “new” smell associated with many household items. New furniture, especially pieces made with pressed wood products like particleboard or plywood, releases chemicals from the binding adhesives. Similarly, new carpeting and vinyl flooring often release compounds from the synthetic fibers, backings, and installation glues.
Freshly applied paints, stains, and protective coatings are major sources of short-term outgassing as the solvents evaporate during the curing process. Products like mattresses, upholstery, and foam padding can also release compounds used in fire retardants and foam production. Even common electronics and dry-cleaned clothing contribute to released gases in an indoor environment.
Volatile Organic Compounds (VOCs)
The primary substances released during the outgassing of consumer products are Volatile Organic Compounds, or VOCs. These are carbon-based chemicals that have a low boiling point, meaning they easily turn into gas or vapor at normal room temperature. VOCs are intentionally incorporated into many products to act as solvents, binders, or to improve product performance.
Specific examples of common VOCs include formaldehyde, which is widely used in resins for pressed wood products and some permanent-press fabrics. Benzene and toluene are other prevalent VOCs, often found in paints, adhesives, and coatings as industrial solvents.
Exposure to high concentrations of VOCs can cause immediate, short-term health effects such as eye, nose, and throat irritation, headaches, and dizziness. Longer-term exposure to certain VOCs has been linked to potential damage to the liver, kidneys, and central nervous system. Some of these compounds are also suspected or known carcinogens.
Reducing Emissions in Your Home
One of the most effective strategies for minimizing exposure is to maximize the ventilation in your home. Opening windows and using exhaust fans helps to dilute and remove outgassed compounds from the indoor air, which is particularly important immediately after introducing new items like paint or furniture.
You can also accelerate the release of chemicals from new products using a technique known as “off-gassing” or “baking out.” This involves placing the new item in a warm, well-ventilated area, like a garage, for several days or weeks before moving it indoors. Since heat increases the rate of emission, this encourages a faster initial release away from living areas.
For continuous air purification, consider using air purifiers that contain an activated carbon filter. While standard HEPA filters remove particles like dust, activated carbon is specifically designed to adsorb and trap chemical vapors and gases. Keeping the indoor temperature lower can also slightly reduce the rate of chemical release from materials already in the home.