There are many sources of indoor air pollution in any home. These include combustion sources such as gas, building materials and furnishings as diverse as deteriorated, asbestos-containing insulation, wet or damp carpet, and cabinetry or furniture made of certain pressed wood products; products for household cleaning and maintenance, personal care, or hobbies; central heating and cooling systems; and outdoor sources such as radon, pesticides, and outdoor air pollution. Some sources, such as building materials, furnishings, and household products like air fresheners, release pollutants more or less continuously. High pollutant concentrations can remain in the air for long periods after some of these activities.
Amount of Ventilation
If too little outdoor air enters a home, pollutants can accumulate to levels that can pose health and comfort problems. Unless they are built with special mechanical means of ventilation, homes that are designed and constructed to minimize the amount of outdoor air that can “leak” into and out of the home may have higher pollutant levels than other homes. However, because some weather conditions can drastically reduce the amount of outdoor air that enters a home, pollutants can build up even in homes that are normally considered “leaky.”
How Does Outdoor Air Enter a House?
Outdoor air enters and leaves a house by: infiltration, natural ventilation, and mechanical ventilation. In a process known as infiltration, outdoor air flows into the house through openings, joints, and cracks in walls, floors, and ceilings, and around windows and doors. In natural ventilation, air moves through opened windows and doors. Finally, there are a number of mechanical ventilation devices, from outdoor-vented fans that intermittently remove air from a single room, such as bathrooms and kitchen, to air handling systems that use fans and duct work to continuously remove indoor air and distribute filtered and conditioned outdoor air to strategic points throughout the house. The rate at which outdoor air replaces indoor air is described as the air exchange rate. When there is little infiltration, natural ventilation, or mechanical ventilation, the air exchange rate is low and pollutant levels can increase.
Identifying Air Quality Problems
Some health effects can be useful indicators of an indoor air quality problem, especially if they appear after a person moves to a new residence, remodels or refurnishes a home, or treats a home with pesticides. If you think that you have symptoms that may be related to your home environment, discuss them with your doctor or your local health department to see if they could be caused by indoor air pollution. You may also want to consult a board-certified allergist or an occupational medicine specialist for answers to your questions.
Measuring Pollutant Levels
The federal government recommends that you measure the level of radon in your home. Without measurements there is no way to tell whether radon is present because it is a colorless, odorless, radioactive gas. Inexpensive devices are available for measuring radon. EPA provides guidance as to risks associated with different levels of exposure and when the public should consider corrective action. There are specific mitigation techniques that have proven effective in reducing levels of radon in the home. (See “Radon” section on epa.gov/iaq for additional information about testing and controlling radon in homes.)
Improving the Air Quality in Your Home ? 3 Strategies:
Usually the most effective way to improve indoor air quality is to eliminate individual sources of pollution or to reduce their emissions. Some sources, like those that contain asbestos, can be sealed or enclosed; others, like gas stoves, can be adjusted to decrease the amount of emissions. In many cases, source control is also a more cost-efficient approach to protecting indoor air quality than increasing ventilation because increasing ventilation can increase energy costs. Specific sources of indoor air pollution in your home are listed later in this section.
Another approach to lowering the concentrations of indoor air pollutants in your home is to increase the amount of outdoor air coming indoors. Most home heating and cooling systems, including forced air heating systems, do not mechanically bring fresh air into the house. Opening windows and doors, operating window or attic fans, when the weather permits, or running a window air conditioner with the vent control open increases the outdoor ventilation rate. Local bathroom or kitchen fans that exhaust outdoors remove contaminants directly from the room where the fan is located and also increase the outdoor air ventilation rate. Advanced designs of new homes are starting to feature mechanical systems that bring outdoor air into the home. Some of these designs include energy-efficient heat recovery ventilators (also known as air-to-air heat exchangers).
There are many types and sizes of air cleaners on the market, ranging from relatively inexpensive table-top models to sophisticated and expensive whole-house systems. The effectiveness of an air cleaner depends on how well it collects pollutants from indoor air (expressed as a percentage efficiency rate) and how much air it draws through the cleaning or filtering element. Also, houseplants have been shown to reduce levels of some chemicals in laboratory experiments. There is currently no evidence, however, that a reasonable number of houseplants remove significant quantities of pollutants in homes and offices.
6 TIPS for Better Home Air Quality:
- Operate the exhaust fan when bathing and showering to limit moisture build up. Be sure to keep the shower curtain or bathtub sliding door open after bathing to increase air circulation.
- Turn on range hood fans to expel contaminants released from food while cooking. Range hoods can also eliminate pollutants such as carbon monoxide which can be released during cooking.
- Ensure that continuous ventilation is provided in addition to the intermittent ventilation systems. This can be achieved using a whole-house comfort ventilator.
- Plan routine maintenance for HVAC equipment to ensure all systems are working properly and performing as intended. Check, clean, or replace furnace and air filters regularly as recommended. Consider installing a “high efficiency particulate” or HEPAfilter for better performance.
- Clean the home regularly to prevent dust, dirt, and pet-hair accumulation.Use safe cleaning products to avoid emitting dangerous chemicals into the air. Many products can release toxic or irritating chemicals when used.
- Purchase low emitting finishes and materials. New or recently installed building materials and furnishings can emit dangerous toxins. Look for products that are certified for low chemical emissions.