In the developed world, people spend an average of about 90 percent of their time indoors. Therefore the indoor environment is, for many, the environment that most influences their health, comfort, and well being. Whatever the quality of the outdoor air, it is the indoor air they breathe.

During the summer of 1999 a diverse group of international specialists in scientific, engineering, and design fields gathered in Edinburgh, Scotland, for the 8th International Conference on Indoor Air Quality and Climate, Indoor Air 99, sponsored by the International Academy on Indoor Air Sciences and the International Society of Indoor Air Quality and Climate. The preamble to the Indoor Air 99 Statement, excerpted above, set the stage for far-ranging discussions on the current state of knowledge and inquiry as to the role of indoor air quality in human health and the quality of life.

The Indoor Air 99 Statement called for both continued research and application to "identify and solve problems with indoor air quality and climate . . . within the domain of many disciplines and professions." The statement concluded with the following recommendation:

Indoor air quality and climate is an important policy area for all nations and for international bodies. Policy should be based on the best current knowledge and advice, with public health placed before political or personal advancement.

Why is indoor air quality an issue?

Indoor air quality is a broad concept. It is a health and comfort issue for a building's occupants. It is a technical issue for designers and builders. It is a management issue for people who are responsible for maintaining a building. It is an economic issue for the owners of a building. And the issues of indoor air quality are sometimes very different for a public space, as opposed to the privacy of a home.

Indoor air quality is a complex issue. A building has a wide variety of air pollutants resulting from the products used to construct and furnish the building, as well as from the activities of the occupants. The heating and cooling system of a building can contribute pollutants. Other pollutants may enter from the external environment. Building conditions, such as temperature and humidity, influence the production of pollutants. The concentration of pollutants in a building is directly related to the ventilation of the structure. And any of these factors can vary dramatically over time.

If we spend about 90 percent of our time indoors today, about half that time is spent in our homes. The quality of air in our homes is critically important to us since it directly affects our health and comfort. The role of laws and regulations, often used to control and improve the quality of air in outdoor or public spaces, is more complex and controversial when it comes to our homes. We want to be safe and healthy, but our home is our castle; it is a private space that we control. So how do we achieve balance?

Understanding indoor air pollution

It is not always easy to detect indoor air quality problems. Some pollutants can be smelled or seen, while others are invisible and/or odorless. Poor air quality may be simply annoying or unpleasant, or it may lead to serious health problems. Irritated eyes and noses, headaches, dizziness, tiredness, asthma, viral infections, and respiratory diseases may result from substances in the air you breathe. Serious effects of poor air quality, however, such as lung cancer, may take years to develop. People react differently to air pollutants, depending on their age, sensitivity, health status, and the type and length of exposure. Improvement of health symptoms after leaving the home is an indication that indoor air quality problems are a factor.

A home with unusual, strong, or lingering odors; stale or stuffy air; or a noticeable lack of air movement could have indoor air quality problems. Poor ventilation may result in noticeable health symptoms after using household or hobby products. Excessive humidity or the presence of molds or mildew are additional signs of air quality problems. Remodeling, weatherizing, or moving new furniture into a home can increase undesirable air quality conditions. Children, whose still developing bodies are smaller, are especially vulnerable. Indoor air quality pollutants contribute to the increasing incidence of childhood asthma. Environmental tobacco smoke, which results in chronic respiratory problems, and dust from disintegrating lead-based paint, especially are developmental and health hazards for young children.

Finding the source--or sources--of pollutants in the home is the first step. The removal or reduction of pollution sources is usually the most cost-efficient and effective way to address air quality problems. The second approach is to understand how the home is ventilated and to apply this knowledge to decreasing the concentration of pollutants in the home.

Indoor air pollutants

Most indoor air pollutants fall into one of the following categories:

• Combustion by-products from fuel burning appliances, including furnaces, water heaters, ranges, and space heaters and tobacco smoking. Examples of potential pollutants include carbon monoxide, nitrogen and sulfur oxides, formaldehyde, and tiny breathable particles. The type of venting system and the maintenance of fuel burning appliances are critical factors in their pollutant potential. Any combustion by-products not vented to the outside of the home can lead to air quality problems.
• Building materials and furnishings such as manufactured wood products, paints, varnishes, waxes, and adhesives. Examples of pollutants include a wide variety of volatile organic compounds (VOCs), sometimes called organic solvents or petroleum distillates. Many VOCs off-gas (evaporate) when the product is new or during hot and humid conditions. Lead and asbestos, no longer used in new construction, are found in older houses and disintegrate or are disturbed in remodeling.
• Household products and chemicals include products used for maintenance, cleaning, personal grooming, and hobbies. Some products, such as sprays, can release chemicals or particles into the air during use. Others off-gas or emit chemicals as the product dries, cures, or ages. Household products having petroleum distillates or other volatile organic compounds usually create more unhealthy emissions than water-based products. However, many "everyday" household products can generate indoor air pollutants if used improperly or without adequate ventilation.
• Biological contaminants from living or once-living organisms, including molds and other fungi; animal dander; pollen; and insect residues, such as from dust mites and roaches. These contaminants can cause odors, lead to allergic reactions, and cause infectious diseases and respiratory problems. Many biological contaminants increase in damp, humid, or poorly cleaned spaces. Good maintenance practices can control moistures and reduce the need for chemical products like pesticides and disinfectants--both of which could add other pollutants to the air.
• Radon, a radioactive gas occurring naturally in rocks and soils in many areas, such as the valley and ridge and Piedmont areas of Virginia. It enters the home through cracks and other openings in contact with the ground. Depending on the structure of the home and the ventilation patterns, levels of radon can rise to become a health risk. Radon is invisible and odorless, causes no immediate symptoms or health effects, and is detected only through specific testing. It is recognized, however, as a major, long-term cause of lung cancer.

Ventilation and indoor air quality

Even in homes with few sources of pollutants, ventilation is needed, especially during seasons when windows and doors are kept shut. Home ventilation is usually measured in air changes per hour (ACH), or how many times per hour the volume of air in a home is replaced with outdoor air. Many factors can affect the ACH rate, including the structure of a home; weather; opening or closing of doors and windows; heating, cooling, and ventilating equipment; and using fans.

Many homes "leak" air--at construction joints, for example--which may help maintain air freshness but wastes energy used in heating and cooling. Newer homes tend to have tighter construction resulting in greater energy efficiency but pollutant build-up as well. Tighter homes are also more susceptible to backdrafting, a situation in which the indoor air pressure is lower than outdoor air pressure. With backdrafting, combustion gases, such as from a furnace, may not be fully exhausted to the outside, or outdoor pollutants, such as radon, may be pulled into the home.

The answer, however, is not to build homes that are more loosely constructed with higher air exchange rates. The cost of inefficient use of energy supplies to heat and cool our homes, as well as the environmental impact of excess energy production, is too significant. Rather, the multi-pronged solution is to look at

• Reduced need for ventilation through better control of indoor air pollutants;
• Cost-effective, heat-recovery mechanical ventilation when appropriate to the season and climate;
• Controlled ventilation that adjusts to times and spaces with higher pollutant production, which is typical of a kitchen range exhaust fan, for example; and
• Greater use of natural ventilation in appropriate climates.

Seeking solutions to air quality problems

Poor indoor air quality in homes is not an easily remediable problem, but rather a complex, multi-faceted issue that defies a simple solution. Some indoor air quality problems create significant health and comfort concerns--and can even be life threatening. Other air quality problems are merely inconvenient. Variation in individual sensitivity complicates the issue. Diagnosing air quality problems is technically difficult, and the severity of the problem may or may not warrant the expense.

In recent years, the importance of indoor air quality in homes has gained greater public awareness. As our society puts increasing emphasis on environmental issues, we become more concerned about the effects of hazardous products. Attention to good health and understanding the role of the built environment in supporting healthy lifestyles are gaining prominence. However, public perception of indoor air quality concerns varies from great alarm to apathy. Lack of knowledge or misinformation limit the public's ability to assess risk and the need for risk reduction action.

Achieving good indoor air quality in our homes requires a two-part approach. First, the home's structure must be designed and built to minimize pollutants inside the home. This includes products to build and furnish the home, construction techniques, and systems to heat, cool, and ventilate. Second, public education is needed to help people understand the issues and risks of indoor air quality, and their own roles and responsibilities. Good air quality requires a commitment to manage and maintain the structure to prevent indoor pollution.

Building codes and air quality

Promotion of healthy indoor air quality is increasingly important in the ongoing process of developing and revising building codes and regulations, which help protect the health and safety of a building's occupants. However, developing the codes is a political process whose outcome can be affected by such issues as housing affordability, technological development and innovation, concern about excess regulation, freedom of choice, and consumer acceptance. Therefore, a desirable code innovation, targeted to improve indoor air quality, may run aground of conflicting priorities and never be implemented.

Many organizations are involved in the code development process. Some develop model building codes, which are representative of the current understanding of the best technologies, product innovations, and construction practices. Many trade organizations and private and government agencies influence the model codes by developing standards and other recommendations. In Virginia, as in many other states, a model code is the basis of a statewide uniform building code. However, the model code can be modified or expanded before adoption. In addition, localities can adopt additional codes beyond the statewide code.

In Virginia the code development process is further complicated by the variety of geographic regions within the state. The coastal (Tidewater), Piedmont, and valley and ridge (mountainous) regions are distinctive in soil conditions, climate, and other factors that directly influence building practices and indoor air quality issues.

To understand the influence of building codes and regulations on indoor air quality, we will briefly look at three issues: radon resistant construction, radon in drinking water, and whole-house ventilation.

Radon-resistant construction

The Environmental Protection Agency (EPA) has developed zone maps of the United States to help locate areas of highest radon risk based on soil and geologic conditions and on the testing of existing buildings. Much of the mountain and Piedmont areas of Virginia fall within Zone 1, the areas of highest risk. In Zone 1 areas, the EPA recommends the inclusion of radon-resistant features--sealing the foundation to prevent gas entry and installing a pipe to vent soil gases from beneath the foundation--in new home construction. These features, which are more economical to add when a house is constructed, could be activated if elevated levels of radon exist. An active effort is under way in Virginia to add radon-resistant construction features to the statewide building code.

Radon in drinking water

Radon can accumulate in ground water. When radon-contaminated water is used in the home, radon is released into the air and becomes an indoor air pollutant. The EPA recently proposed a new standard that allows a higher level of radon in water only if a state is conducting a comprehensive program to reduce overall levels of radon in indoor air. The proposed new regulations were released last fall for public comment.

Whole-house ventilation

The American Society of Heating, Refrigeration and Air-conditioning Engineers (ASHRAE) has played a key role in developing a variety of standards on heating, cooling, and ventilating buildings that are incorporated into model building codes. ASHRAE has just proposed a revision of its Standard 62.2, "Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings," and has sent it out for public review. The controversial standard recommends requiring mechanical ventilation of homes to compensate for tighter construction techniques and lifestyle changes that result in less frequent use of natural ventilation (windows).

What can policymakers do?

Regulatory approaches
The three issues discussed above--radon-resistant construction, radon in drinking water, and whole-house ventilation--are examples of changes in the requirements for building homes that can lead to improved air quality. Another would be the requirement to install carbon monoxide detectors in all homes that have fossil-fuel-burning appliances. This includes any home that uses natural or propane gas, oil, wood, coal, or similar fuels. In much the same way that a smoke detector is a fire safety device, a carbon monoxide detector does not actually change the air quality but is important to warn of danger.

A change in ownership or occupancy of a home, through sale or rental, creates an opportunity for actions to improve air quality. Examples include a radon test, a test for lead paint, an evaluation and maintenance of the heating and cooling system, an inspection for mold, or a pest inspection. Although the new buyer or renter always has the option to request such tests--inspections, evaluations, and repairs to improve air quality--with the exception of lead, that right is not assured. However, a municipality can require inspections, tests and standards of repair during the home sale or rental process. In addition, these actions can be required as contingencies to receiving financing. Finally, greater knowledge and advocacy of air quality issues by the real estate community can change common practices in the housing market and better protect the buyers' or renters' options.

Another regulatory approach to improving air quality is to limit or prohibit the sale and/or use of products that contribute to poor air quality. For example, any fuel-burning combustion appliance contributes pollutants to indoor air if it is not properly and effectively vented to the outside of a building. Therefore, unvented fuel-burning appliances, such as space heaters, fireplace logs, or grills, should not be permitted in homes.

Public education

A well designed and constructed home can promote healthy indoor air. However, how the home is managed and maintained is also critical to providing a healthy living environment. Public education is needed to help Virginians understand the issues of indoor air quality and their responsibility in promoting quality air in their own homes. For example, regularly maintaining the heating, cooling, and ventilating equipment; controlling moisture in the home; keeping the home clean and well-maintained to minimize infestations of pests; choosing furnishings and household products that are least likely to emit pollutants; and testing the home for radon and lead-based paint are all practices that homeowners can learn and implement to improve the quality of indoor air. Likewise, understanding factors--e.g., the likelihood of lead-based paint in a particular home, which areas of the state have the greatest risk of high radon levels, or the relationship between indoor air quality and childhood respiratory illnesses--can help household members evaluate their chances of having indoor air quality problems and lead them to make informed choices about their home.

Education about indoor air quality in Virginia's homes is a public concern. It requires unbiased educators who present the most accurate technological and health-oriented information. Educational programs must be developed from a holistic perspective that considers how people really live in their homes. This perspective recognizes that indoor air quality, while critical to health and comfort, is only one issue in providing and managing safe, affordable, and quality housing for Virginians.

While public education is critical to helping Virginians understand potential air quality problems, solutions must also be available. Training programs are needed to prepare building industry professionals in the diagnosis and remediation of air quality problems. Certification and licensing programs, such as those for lead inspector technicians and risk assessors, provide standards of performance and public credibility. Grant programs and tax incentives can be used to encourage building improvements, such as lead abatement or improved ventilation systems, and to make them economically feasible. Solutions to promote quality indoor air must be affordable, practical, convenient, and adaptable.

Moves in the right direction

Virginia coalition
Private organizations and businesses need to partner with government and educational agencies to address indoor air quality concerns. One such partnership for education and advocacy on indoor air quality issues is the Virginia Indoor Air Quality Coalition, which involves the National Association of Counties, American Lung Association of Virginia, Virginia Cooperative Extension, and the Fairfax County Department of Health. Other agencies, organizations, and businesses have also been involved. Activities of the coalition have included statewide meetings to increase knowledge, awareness, and networking on indoor air quality issues, a newsletter, and advocacy on issues such as radon resistant construction.

The Virginia Indoor Air Quality Coalition provides a starting point for statewide efforts to address air quality concerns. However, greater participation by state agencies and organizations and increased visibility for the coalition are needed.

Healthy air for homes

A national education program, "Healthy Indoor Air for America's Homes," began as a partnership between the Environmental Protection Agency (EPA) and the U.S. Department of Agriculture Cooperative State Research, Education, and Extension Service (USDA-CSREES). Cooperative Extension faculty from six land-grant universities, including Virginia Tech, worked together to develop this educational program, which is now active in 46 states and territories. Each participating state works in partnership with various businesses and industries, public and private organizations, and local governmental agencies to reach the targeted audience and deliver the educational program.

In Virginia, the Virginia Cooperative Extension (VCE) has led the program. Topics for educational programs have included childhood lead poisoning, environmental hazards in home remodeling, safe and healthy daycare environments for children, carbon monoxide, and safe use of household chemicals. A variety of educational methods have been used, including workshops, publications, newsletters, Internet sites, and exhibits.

"Healthy Indoor Air for America's Homes" is a model for developing partnerships and delivering a public education program to address environmental issues. In particular, this program provides an excellent model for educational programs that address the increasing concern about children's health issues and the role of the home environment in these issues. Increased funding for this program would allow it to expand its audience.

Breathe easy, breathe healthy

Good air quality in our homes is critical to our health and well being. Consequently, we must continue to address how we design and build our homes to minimize pollution and provide healthy air to breathe. We should develop codes and regulations for our buildings that protect indoor air quality without sacrificing affordability. And we need to educate our citizenry on how to take responsibility for making choices to furnish, maintain, and manage their homes to promote good air quality.

Indoor air quality

For information on indoor air quality, browse the Environmental Protection Agency's Indoor Environments Division web site. Or call the National Center for Environmental Publications and Information (NECPI) at 1-800/490-9198 for a list of publications on indoor air quality.

Radon-resistant construction

To learn more about the effort in Virginia to adapt the building code to include radon-resistant construction, contact Steven Church, environmental health specialist with the Fairfax County Health Department, by writing Division of Environmental Health, 10777 Main Street, Suite 115, Fairfax, VA 22030-6903 or calling 703/246-2338.

Radon

Information on radon, including radon-resistant construction and the new radon in drinking water standards, is available by calling the Radon Hotline at 1-800/SOS-RADON, visiting EPA's radon web site, or writing the Bureau of Radiological Health, Virginia Department of Health, Main Street Station, 1500 East Main Street, Richmond, VA 23219.

ASHRAE Standard 62.2

Visit their web site for information on the proposed standard "Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings" and other involvement of the American Society of Heating, Refrigeration, and Air-conditioning Engineers (ASHRAE) in developing ventilation standards.

Virginia Indoor Air Quality Coalition

To receive facts about the coalition or to be added to its mailing list, contact the American Lung Association of Virginia, P.O. Box 7065, Richmond, VA 23221-0065, 804/355-3295.

"Healthy Indoor Air for America's Homes"

Contact your local office of the Virginia Cooperative Extension for information about this program in your area. Or visit the program's national web site.

Lead

Facts about lead are available by contacting the National Lead Information Center at 1-800-LEAD-FYI, or the Lead Safe Virginia Program, Virginia Department of Health, Main Street Station, 1500 East Main Street, Richmond, VA 23219.
--Kathleen Parrott

Kathleen Parrott, an associate professor and Extension housing specialist at Virginia Tech, helped develop and co-authored two national environmental curricula: "Healthy Indoor Air for America's Homes" and Home*A*Syst. She co-edited a special issue of Housing and Society: "Residential Indoor Air Quality: Focus on Issues and Education" and was associate editor of Housing and Society. She has also served as the president of the American Association of Housing Educators.