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Indoor Air Quality (IAQ) is a term referring to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants. Indoor air quality may be affected by multiple factors including, but not limited to, the use of synthetic building materials and furnishings, the use of air purifiers and other pollutant sources, such as room air fresheners, and the use of various chemicals for pesticide management and cleaning. Inadequate ventilation can increase indoor pollutant levels by not bringing in enough outdoor air to dilute emissions from indoor sources and by not carrying indoor air pollutants out of the building. Indoor pollution sources that release gases or particles into the air are the primary cause of indoor air quality problems in homes. High temperature and humidity levels can also increase concentrations of some pollutants.

Why is this important to your community?

Each resident, worker, and visitor within the CONNECT region is directly impacted each day by the quality of indoor air. Improvements to indoor air quality can have positive impacts on individual health, economic productivity, and the overall value of the region’s built environment.

According to the U.S. Environmental Protection Agency, growing scientific evidence suggests that the air within homes and other buildings can be more seriously polluted than the outdoor air in even large industrialized cities. Other research indicates that people spend approximately 90 percent of their time indoors, making the risks to health from exposure to air pollution indoors potentially greater than the risks outdoors. The US Consumer Product Safety Commission also warns that although pollutant levels from individual sources may not pose a significant health risk by themselves, most buildings have more than one source that contributes to indoor air pollution and a serious risk from cumulative exposure to these sources exists.

Mold, mildew, dust mites, animal and insect parts are all agents that can adversely affect indoor air quality and cause allergic illness, trigger asthma, cause respiratory infections, and other health problems. Volatile organic compounds (VOCs) and pollutants such as radon, carbon monoxide, excessive carbon dioxide and chemical fumes―emitted from paints, solvents, building materials, air fresheners, dry-cleaned clothing, aerosol sprays, adhesives, fabrics and other sources― can cause or worsen irritation of the eyes, nose and throat, headaches, fatigue, and more severe illnesses, including heart disease, cancer, and other serious long-term conditions, and even death. The likelihood of immediate reactions to indoor air pollutants depends on several factors including an individual’s age and preexisting medical conditions, but sometimes the treatment is simply eliminating the person's exposure to the source of the pollution, if it can be identified.

How does it work?

Improvements to indoor air quality can be achieved through strategies to control or eliminate sources of pollution, improve ventilation, or clean the air. Having a significant impact on the overall quality of a region’s indoor air involves a coordinated approach among the public sector, the private business community, individual homeowners, and the building design/engineering/construction industry. To date, the focus on indoor air quality improvement has been on providing resources to distinct groups including: homeowners to improve their individual home environments, educational facilities managers to improve the quality of air in schools, and the green building community to support upgrades to commercial and office buildings. Improvements to the built environment work to improve the quality of the indoor air and mitigate the harmful impacts on health and productivity.

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Using the Tool

Local governments can improve air improve quality, public health and productivity by developing and adopting IAQ policies for public buildings. They can also support private and institutional sector efforts by encouraging green building techniques and green property management procedures both for nonresidential and residential buildings to improve air quality and public health. Indoor air quality is influenced by decisions made at the building design and construction stages, as well as through day-to-day living choices made by each building owner, operator, occupant and visitor. Improvements to indoor air quality are focused on three basic strategies, outlined by the EPA’s Indoor Environments Division (IED); Source Control, Ventilation Improvements, and Air Cleaners. Approaches to implementing these strategies vary across building type, location, and scale, but the basic components remain consistent:
  • Source Control
    • The most effective way to improve indoor air quality is usually to eliminate sources of pollution or reduce their emissions. Some sources, including materials 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. In construction and renovation, the selection of materials with low-emitting products, formaldehyde-free materials, and using only low-toxicity and low-emitting paint also help eliminate sources of indoor air pollution.
    • In nonresidential structures, source control can be achieved by conducting regular building walkthrough inspections, including routine moisture inspections. Building owners, property managers, and tenants should adopt mold prevention and remediation policies and plans. Indoor humidity levels should be maintained between 30% and 60%. Commercial and institutional property management teams should be testing periodically for radon and making the necessary mitigations to eliminate any negative impacts. These managers should also implement a hazardous materials plan that includes instructions for appropriate usage, labeling, storage, and disposal. Chemical management and inventory plans are also effective in controlling the source of indoor air pollution, as well as the practice of conducting any necessary pollutant-releasing activities during times when the building is unoccupied. The implementation and enforcement of smoke free and anti-idling policies can have a significant impact on negative effects of outdoor air on indoor air.
  • Ventilation Improvements
    • Concentrations of indoor air pollutants can also be reduced by increasing the amount of outdoor air flow through a building. 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. New homes with advanced designs sometimes feature mechanical systems that bring outdoor air into the home, including energy-efficient heat recovery ventilators, also known as air-to-air heat exchangers.
    • In commercial and larger scale facilities management, including schools, this includes establishing a maintenance plan that calls for regular HVAC system inspections, requires regular filter changes, and checks to ensure condensate pans are draining. As a practice, outdoor air ventilation should be provided in accordance with ASHRAE Standard or local code (e.g., clean air supply diffusers, return registers, and outside air intakes). In practice, all unit ventilators should be kept clear of books, papers, and other items.
  • Air Cleaners
    • The US Consumer Product Safety Commission identifies several types and sizes of air cleaners on the market, ranging from relatively inexpensive table-top models to sophisticated and expensive whole-house systems. Although some air cleaners are highly effective at particle removal, most are not designed to remove gaseous pollutants. 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 (expressed in cubic feet per minute.)

Where has it worked?

Jefferson County Public Schools - Louisville, KY

Dr. Donna HargensImage Source: Dr. Donna Hargens.



Jim Vaughn

About the Program

In 2002, the Jefferson County Public School District successfully implemented a district-wide Indoor Air Quality (IAQ) improvement program, which is still in operation today. Using information provided by the Environmental Protection Agency and the IAQ Tools for Schools Action Kit, administrators took several steps to improve knowledge, communications and teamwork. The district now offers training for team building and problem solving skills focused on managing and preventing IAQ problems.

Why it works

Under the direction of a District IAQ Coordinator, team members conduct weekly walkthroughs in all schools, implement an integrated pest management program, conduct routine radon testing and mitigation, and regularly monitor airflow in its buildings. These efforts have led to measurable results, including rising student attendance rates and test scores as well as fewer complaints about IAQ issues. The school district has been recognized in 2002 by the EPA with an Excellence Award, and in 2006 for a National Model of Sustained Excellence.