Carpets and Air Quality
- What is carpet made of?
- How is carpet installed?
- Can carpet affect indoor air quality?
- Can carpet affect health?
- If I already have wall-to-wall carpeting, what can I do to reduce health risks?
- If I still plan to install carpeting, what can I do to reduce health risks?
- Where can I get more information?
What is carpet made of?
Most carpet is made with man-made or synthetic materials. However, carpets can also be made of wool or other natural materials. Most carpet has at least two parts: the cushion or pad for support and noise reduction, and the carpet itself.
There are several types of carpet construction. Most synthetic carpet is “tufted.” Tufted carpet is made by machines that stitch and cut or loop yarn, and then attach the yarn to a backing. The yarn is made of a nylon, acrylic, or polyester. This backed yarn is often attached to another backing with a latex rubber product. This second backing helps to make the carpet more stable.
How is carpet installed?
Carpet usually is either glued or stapled to the floor. If the flooring underneath the carpet is wood or plywood, the carpet might only be stapled down. In some cases, only the edges of the carpet are glued down. If the carpet is installed on a cement surface, it is often glued down. In general, this is the case in schools, office buildings and basements.
Can carpet affect indoor air quality?
Carpet, of course, is commonly used in buildings of all types, with relatively few negative health consequences. Both old and new carpet, however, can affect indoor air quality. Carpet can release chemicals into the air and also can harbor allergens like mold spores or pet dander.
VOCs: Like many other furnishings, products, and building materials in the modern world, carpets can be a source of volatile organic compounds (VOCs). (See Fact Sheet on Volatile Organic Compounds) If the carpet is glued to the floor, the adhesives and seam sealers used often contain solvents (a source of VOCs). Carpet pads may also be a source of VOCs. VOCs that have been associated with carpet problems in the past include styrene, “4-PC” (4-Phenylcyclohexane), BHT (butlylated hydroxytoluene), and xylene.
Some cleaning products used to maintain a carpet contain solvents. These solvents are often petroleum-based and are sources of VOCs. If carpet is treated with products that may lessen odors, resist dirt, repel stains, or kill germs or pests, then these products may also be sources of additional VOCs.
- Allergens: Whether it is dirt tracked in from the outdoors, the millions of skin cells people shed daily, the dander from cats and dogs, or the common presence of mold spores, carpet can be an excellent place for such debris to gather and microbes to grow. The older the carpet, the more likely it contains higher amounts of dirt and microbes. When there is foot or air movement across the carpet, or when the carpet is vacuumed with a poorly filtered device, the dust and organisms can easily become airborne.
During periods of high humidity, flooding, or under damp conditions, mold, dust mites and bacterial growth can increase. (See Fact Sheet on Mold). Similar conditions can be caused by condensation from carpet on cement, tracked-in snow or rainwater, and pipe or roof leaks. Even shampooing a carpet may contribute to problems if the water is not hot enough or if the carpet remains wet or damp for more than 24 hours.
Although steps can be taken to reduce the amount of dirt accumulation, biological growth, and airborne microbes, the porous nature of carpeting tends to accumulate pollutants. A hard, easier-to-clean floor surface such as wood or tile does not, by its nature, have this problem.
Can carpet affect health?
For the general population, the amounts of VOCs from carpet and adhesives do not appear to affect health. However, for the young, the elderly, and people with lung conditions, allergies and allergic-type sensitivities, fairly low amounts of VOCs may have health effects. Examples of possible health effects are headaches, nausea, irritation to eyes, nose, and throat, and difficulty breathing.
Usually, physicians recommend that people with allergies to dust or pet dander, for example, avoid those allergens, as well as the conditions that support the generation or accumulation of such allergens. Some examples include wood stoves ashes, living spaces in damp basements, wall-to-wall carpeting, feather pillows, and stuffed toys or stuffed animals.
Infants and children, due to their closeness to the carpeting, can be at increased risk to inhalation exposure.
If I already have wall-to-wall carpeting, what can I do to reduce health risks?
The best way to reduce risks is to carefully remove carpeting and install a hard, easily cleaned flooring such as tile, vinyl, or wood. However, if you choose to keep the carpeting, the following actions can reduce microbial problems.
- Remove shoes and boots before stepping on carpeted areas.
- Place a clean-off mat, which is likely to capture much of the outside dirt and debris, at the entrance of the structure; and clean the mat regularly.
- Don’t allow pets, including birds, in carpeted areas.
- Don’t conduct activities that generate dust and debris in carpeted areas.
- Use a good filtering vacuum cleaner regularly. A High Efficiency Particulate Air (HEPA) filter is one of the best features of a good filtering vacuum cleaner. A HEPA filter is 99.97 percent efficient, down to 0.3 microns.
- Don’t saturate carpeting if you shampoo it. Use a low or no-solvent cleaning compound; use a water temperature of 140°F; use a good water extractor; use a dehumidifier and fans in the room. The carpeting should be completely dry within 24 hours of wet cleaning.
- Be aware that some carpet comes already treated with anti-microbial products. Consider avoiding use of pesticides or other anti-microbial products on carpeting due to possible adverse effects with infants, children, and “sensitive” people.
It is very difficult to completely dry carpeting within 24 hours if severe flooding has occurred on the carpeted surface. In such situations, consider carpet removal.
If I still plan to install carpeting, what can I do to reduce health risks?
There are several ways to reduce health risks:
- Use low-pile carpet.
- If possible, do not use adhesives to glue the carpet down, or use low-VOC adhesives.
- Install carpet only in low traffic areas.
- Don’t install carpet in kitchens, dining areas, or bathrooms.
- Don’t install carpet on cement basement floors, especially if the basement is damp.
- Consider alternatives such as using throw rugs on hard surfaces; these rugs tend to be easier to clean than installed carpeting.
- Avoid using wall-to-wall carpet in high traffic buildings such as schools, banks and shopping malls.
- Before the carpet is installed, ask the retailer (carpet store or installer) to air out the carpeting for at least 24 to 48 hours in the store or warehouse.
- During the installation, make sure the area is well ventilated. If the room has a ventilation system, operate that system on 100 percent fresh air and 100 percent exhaust. If a mechanical ventilation system does not exist, using one or two fans in windows may help to provide fresh air to the room and exhaust the VOCs and odors. One way to use two fans would be to have one facing in (providing fresh air), and one fan facing out (exhausting diluted air). Use caution if you use an exhaust-only system or fan, as this may contribute to backdrafts with wood stoves or other heaters.
- After the carpet is installed, air out and do not use the room for at least 72 hours.
DO NOT ATTEMPT to “bake out” the VOCs and odors by closing off air movement into and out of the room or by raising the temperature. At one time, this was thought to be helpful, but has been shown to make the situation worse.
Where can I get more information?
For more information, visit our Indoor Air Quality Resource Guide.