Department of Health and Human Services

Offices and Commercial Buildings

Sources of Indoor Air Pollutants

Over the past few decades, concerns regarding indoor air pollutants have increased for variety of reasons. Contributing to poor indoor air quality (IAQ) are construction of more tightly sealed buildings, reduced ventilation rates to save energy, the use of synthetic building materials and furnishings, and increased use of chemical products such as pesticides, housekeeping supplies, and personal care products. The four basic factors that affect IAQ are indoor air pollutant sources; heating, ventilation, and air-conditioning (HVAC) systems; pollutant pathways; and occupants.

Typical sources of indoor air pollutants and conditions that can have an impact on IAQ in buildings:

• Mold and Biologicals
• Moisture
• Temperature and Humidity Control
• Humidity and Microbial Growth
• Environmental Tobacco Smoke
• Combustion Products, including Carbon Monoxide
• Volatile Organic Compounds
• Particulates
• Radon
• Pesticides
• Heating, Ventilating & Air Conditioning (HVAC) Systems
• Asbestos
• Lead-Based Paint
• Information on Indoor Air Quality Program for Large Buildings

See also:
US EPA: Healthy Buildings, Healthy People: A Vision for the 21st Century

Mold and Biologicals: Mold, mildew, dust mites, animal and insect parts are all agents that can adversely affect indoor air quality. Moisture-related problems in buildings can result in the growth or amplification of biological or microbial organisms such as mold, mildew, dust mites and bacteria. Exposure to these organisms can increase risk of allergic illness, trigger asthma, cause respiratory infections, or have other health effects. Typical sources of moisture are structural leaks, plumbing leaks, flooding, and HVAC-related humidity control problems. Proper cleaning and building maintenance, especially moisture control, are essential in the control of mold and other biological agents.

For more detailed information, see:
NC DHHS/OEEB: Mold and Human Health
US EPA: Mold Remediation in Schools and Commercial Buildings
NC State University: Moisture Control and Prevention Guide

Moisture: The most important factor in the growth and spread of mold and other biological agents is moisture. Typical sources include structural leaks, roofing leaks, plumbing leaks, and malfunctioning or improperly sized heating, ventilation, and air conditioning systems. Elimination of moisture is essential to eliminating mold, mildew and other biologicals.

See also:
NC State University: Moisture Control and Prevention Guide
US EPA: Mold Remediation in Schools and Commercial Buildings

Temperature and Humidity Control: Temperature and humidity control are two of the most important indicators of a building's IAQ. They are also of extreme importance in the occupants' perception of IAQ. Achieving thermal comfort (temperature and humidity conditions that are acceptable to occupants) for all occupants is a difficult, if not impossible, task.. The American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) has published recommended standards for thermal comfort parameters. Maintaining a building within the following ranges of temperature and relative humidity will satisfy the thermal comfort requirements of most occupants.

Humidity and Microbial Growth: In addition to thermal comfort, the control of relative humidity is important to limit the growth of microorganisms such as mold and dust mites. To control microorganisms, it is best to keep relative humidity below 60% (to control mold) and 50% (to control dust mites) at all times, including unoccupied hours. High relative humidity can foster proliferation of mold and dust mites.

Environmental Tobacco Smoke: Second-hand smoke, or environmental tobacco smoke (ETS), is a mixture of the smoke given off by the burning end of a cigarette, pipe or cigar, and the smoke that is exhaled from the lungs of the smoker. ETS can cause significant IAQ problems in buildings. ETS contains more than 4,000 chemical compounds, approximately 40 of which are carcinogens or suspected carcinogens. Secondhand smoke has been classified by the U.S. Environmental Protection Agency (EPA) as a known cause of lung cancer in humans (Group A carcinogen). Children who breathe ETS are more likely to suffer from ear infections, pneumonia, bronchitis, and other lung diseases. ETS can increase the risk of asthma attacks in persons with asthma. For all these reasons consideration should be given to allowing smoking only in properly ventilated, dedicated smoking lounges or outside.

For additional information on smoking and ETS, see:
NC DHHS: Tobacco Prevention and Control Branch
US EPA: Secondhand Smoke/ETS

Combustion Products, including Carbon Monoxide: Sources of combustion products include unvented fossil-fuel heaters, unvented gas stoves and ovens, and back-drafting and malfunctioning furnaces and water heaters. The health concerns caused by combustion products range from mild health effects to death. Carbon monoxide, a deadly gas, kills over 200 people year in the United States. Other pollutants, such as nitrogen oxide, can cause breathing problems, particularly in sensitive individuals, and can trigger asthma attacks. To ensure that combustion pollutants do not create IAQ problems, the following steps should be taken:

1. Vent all potential sources outside the building.
2. Conduct regular maintenance and inspection of all systems.

For detailed information, see:
US EPA: What You Should Know About Combustion Appliances and Indoor Air Pollution
US EPA: Carbon Monoxide
US EPA: Protect Your Family and Yourself From Carbon Monoxide Poisoning

Volatile Organic Compounds: Volatile organic compounds (VOCs) are emitted from paints, solvents, building materials, air fresheners, dry-cleaned clothing, aerosol sprays, adhesives, fabrics and many more sources. In fact, indoor air may contain several hundred different VOCs. Some of these VOCs can cause eye, nose, and throat irritation; headaches; loss of coordination; nausea; and damage to the liver, kidneys and central nervous system. Some of these chemicals can cause cancer in animals; some are suspected or known to cause cancer in humans. One of the more common VOCs found indoor air is formaldehyde. Formaldehyde is an important chemical and can be found in many products including durable-press drapes and other textiles; particleboard products such as paneling, cabinets and furniture; tobacco smoke; and adhesives. Formaldehyde acts as an irritant to the eyes, nose and throat, and can cause tearing of the eyes, coughing and bronchial spasms. Formaldehyde is also listed as a suspected human carcinogen.

For additional details on VOCs, including sources, health effects, and control methods, see:
US EPA: Organic Gases (VOCs)
US EPA: Formaldehyde
US CPSC: Update on Formaldehyde
California Air Resources Board: Reducing Formaldehyde in Schools
US EPA: Pesticides
NC DHHS: What You Should Know About CCA-Treated Wood

Particulates: Airborne particles include combustion products, dust and pollen. Health effects from exposure to respirable-size particles in the air depend on the types and concentrations of particles present, the frequency and duration of exposure, and individual sensitivity. Health effects can range from irritation of the eyes and/or respiratory tissues to more serious effects, such as cancer and decreased lung function. Biological particles such as animal and insect allergens, viruses, bacteria, and molds, can cause allergic reactions or infectious diseases.

See also:
US EPA: Residential Air Cleaning Devices: Summary Of Available Information
US EPA: Respirable Particles/Combustion Products

Radon: Radon is a naturally occurring, invisible, odorless gas that comes from natural deposits of uranium in soil, rock, and water. It is harmlessly dispersed in outdoor air, but when trapped in buildings, it can be harmful, especially at elevated levels. Radon is a radioactive decay product of radium, which is itself a decay product of uranium. Uranium and radium are both common elements in soil. In North Carolina, piedmont and mountain counties are estimated to have the greatest proportion of homes with elevated levels of radon.

See also:
NCSU / NC DENR: Division of Radiation Protection

Pesticides: The uses of pesticides are regulated under both federal and state law. In North Carolina, the Department of Agriculture and Consumer Services (NC-DACS) regulates the use of pesticide products, while staff in the North Carolina Department of Health and Human Services work to address public health concerns with regard to pesticides.

For additional information:
National Pesticide Information Center
NC Department of Agriculture & Consumer Services: Structural Pest Control Division
US EPA: Office of Pesticide Programs

Heating, Ventilating & Air Conditioning (HVAC) Systems: HVAC systems should be designed to meet the needs of a specific building based on its design, use, and occupant activities. The HVAC system should filter the air, heat or cool as necessary, and control relative humidity during the cooling season. Some systems also introduce outdoor air during this process to dilute building contaminants. After all these actions take place, the tempered air is then circulated throughout the structure. A poorly maintained HVAC system can allow water to build up in the unit, creating conditions where the system itself can become a reservoir for biological contaminants. Inadequate systems can also allow high moisture levels that foster the growth of mold and mildew. For these reasons, it is very important that HVAC systems be inspected on a regular basis to ensure that the systems are clean and functioning as designed.

See also:
US EPA: Fact Sheet: Ventilation and Air Quality In Offices

Asbestos: Some products used in buildings may contain asbestos. If you have concerns about asbestos in your building refer to the NC DHHS web site, "Asbestos in North Carolina."

Lead-Based Paint: Lead is a heavy metal that was used in the manufacture of paint (before 1978) and in other products such as plumbing pipes, solder and leaded gasoline. When paint containing lead deteriorates, tiny lead particles and lead dust can contaminate buildings and the environment. Regulations now limit the amount of lead used in paint and other applications. However, because lead lasts a long time, lead pollution remains a health hazard, particularly in older buildings. For fact sheets and more information, refer to the NC DHHS web site, "Lead Poisoning in North Carolina."

Indoor Air Quality Program for Large Buildings The U.S. Environmental Protection Agency has developed a guidance program titled "IAQ in Large Buildings," which can be found on the EPA web site.

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