Formaldehyde is a colorless, strong-smelling gas found in many products and materials. While naturally produced in small quantities, it is also a toxic substance and a human carcinogen. Its widespread use in manufacturing means its presence in indoor air can pose health concerns.
Common Sources of Formaldehyde Exposure
Exposure to formaldehyde comes from various indoor sources. Building materials are a prominent source, particularly pressed-wood products like particleboard, hardwood plywood paneling, and medium-density fiberboard (MDF). These materials often use adhesives containing urea-formaldehyde (UF) resins, which can release formaldehyde gas into the air over time, a process known as “off-gassing.” MDF, with its higher resin-to-wood ratio, is often the highest-emitting pressed wood product.
Many common household products also contain formaldehyde. These include permanent-press fabrics, glues, paints, wallpapers, and certain cleaning agents and disinfectants. Some personal care products, like cosmetics, shampoos, and hair smoothing treatments, can also contain formaldehyde or formaldehyde-releasing chemicals. Even products labeled “natural” or “organic” might contain varying levels due to preservatives.
Combustion processes also contribute to formaldehyde levels. Tobacco smoke contains formaldehyde, exposing both smokers and those breathing secondhand smoke. Unvented fuel-burning appliances, such as gas stoves, wood-burning stoves, and kerosene heaters, also produce formaldehyde as a byproduct. Automobile exhaust is a major source of formaldehyde in outdoor air, which can infiltrate indoor spaces.
Formaldehyde is also prevalent in professional and industrial settings. Workers in industries that manufacture formaldehyde or formaldehyde-based resins, as well as those involved in woodworking and furniture making, may experience higher exposure levels. Laboratory workers and morticians frequently encounter formaldehyde due to its use as a preservative.
Health Effects of Formaldehyde Exposure
Formaldehyde exposure can lead to various health effects, depending on concentration and duration. Short-term, or acute, exposure to even low levels can cause immediate irritant symptoms. These often include watery eyes, a burning sensation in the eyes, nose, and throat, coughing, and wheezing. Some individuals may also experience nausea and skin irritation, such as dryness, flaking, cracking, and dermatitis.
Individuals with respiratory conditions like asthma may be more sensitive to formaldehyde, experiencing symptoms like chest tightness and shortness of breath at lower concentrations. High levels of exposure can lead to more severe reactions, including inflammation of the lower respiratory tract, throat swelling, and fluid accumulation in the lungs. Direct contact with liquid formaldehyde solutions can also cause serious burns to the skin or eyes, potentially damaging the cornea.
For long-term, or chronic, effects, formaldehyde is classified as a “known human carcinogen” by organizations like the International Agency for Research on Cancer (IARC) and the U.S. National Toxicology Program (NTP). Studies link formaldehyde exposure to specific cancers in humans, including nasopharyngeal cancer (affecting the upper throat behind the nose) and myeloid leukemia, a type of blood cancer. Some research also suggests a possible link to nasal sinus cancer.
Identifying and Reducing Exposure in Your Home
Reducing formaldehyde levels in your home involves practical strategies focused on ventilation and source control. Increasing ventilation is an effective method to lower indoor concentrations. This can be achieved by regularly opening windows and doors to allow fresh outdoor air to circulate, particularly after introducing new furniture or materials. Utilizing exhaust fans in kitchens and bathrooms also helps remove indoor air pollutants.
Controlling formaldehyde sources within your home is another important step. When purchasing pressed-wood products like particleboard or MDF for furniture, cabinetry, or subflooring, look for items certified as low- or no-formaldehyde, or those compliant with standards like ANSI or California Air Resources Board (CARB-ATCM). Products made with phenol-formaldehyde (PF) resins, often used in exterior-grade pressed wood, emit considerably lower levels than urea-formaldehyde (UF) resins. Washing new permanent-press clothing before wearing it can also help reduce initial formaldehyde release.
Maintaining moderate temperature and humidity levels can further reduce formaldehyde off-gassing, as heat and humidity accelerate its release from products. Using air conditioning and dehumidifiers can help regulate these factors. For combustion sources, ensuring gas stoves, wood-burning stoves, and fireplaces are properly maintained and vented outdoors can minimize formaldehyde emissions.
Some air purifiers with activated carbon filters can help remove formaldehyde and other volatile organic compounds (VOCs) from the air. While HEPA filters are effective for particles, activated carbon captures gases. If concerns about formaldehyde levels persist, home test kits are available to measure concentrations, or professional indoor air quality consultants can be hired for comprehensive testing.