Indoor Air Quality

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.

Sources of indoor air pollutants

Indoor air pollutants have increased over the part few decades for variety of reasons. Contributing to indoor air quality issues in homes 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 affecting indoor air quality (IAQ) are indoor air pollutant sources; the heating, ventilation, and air-conditioning (HVAC) system; pollutant pathways; and occupants.

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

Moisture and Biologicals
Combustion Products, including Carbon Monoxide
Environmental Tobacco Smoke
Formaldehyde
Radon
Household Products and Furnishings (VOCs)
Particulates
Lead-Based Paint
Asbestos
A note about Asthma

Radon

Radon is a naturally occurring, invisible, odorless gas that comes from deposits of uranium in soil, rock, and water. It is harmlessly dispersed in outdoor air, but when trapped in buildings, can be harmful, especially at elevated levels. Radon is a radioactive decay product of radium, which is a decay product of uranium. Uranium and radium are both common elements in soil.

Sources of radon in your home

Most indoor radon enters homes from the soil or rock beneath it when Radon and other gases rise through the soil and get trapped under the house. When warm air rises naturally inside the home, it creates a vacuum in the lower areas of the house. The natural reaction to this vacuum is air from beneath the structure containing radon is sucked up into the home through openings (cracks, doors, windows) on the lower levels. Radon gas enters the same way air and other soil gases enter the home; through cracks in the foundation floor or walls, hollow-block walls, and openings around floor drains, heating and cooling ductwork, pipes, and sump pumps. Once inside, the radon can become trapped and concentrated.

Outdoor air that is drawn into a building can also contribute to the indoor radon level. However, the average outdoor air level of radon is normally so low that it does not create a problem.

Radon may also be dissolved in water, particularly well water. After coming from a faucet, about one ten thousandth of the radon in water is typically released into the air. The more radon there is in the water, the more it can contribute to the indoor radon level.

Trace amounts of uranium are sometimes incorporated into materials used in construction. These include, but are not limited to concrete, brick, granite, and drywall. Though these materials have the potential to produce radon, they are rarely the main cause of an elevated radon level in a building.

Radon has been found in elevated levels in many counties throughout North Carolina. However homes in the coastal plain of North Carolina usually have low radon levels, while the upper piedmont and mountain areas have the greatest proportion of homes with elevated levels of radon.

Radon and your health

Exposure to radon is the second leading cause of lung cancer in the US behind smoking. It is estimated that radon causes about 20,000 deaths per year.

The health risk from radon occurs when it is inhaled. Radon gas decays or breaks down into radioactive particles which can damage lung cells and lead to lung cancer. Lung cancer risk is based on years of exposure and the concentration of radon to which one is exposed. The higher the radon level and number of years of exposure, the greater one's risk of developing lung cancer.

Breathing radon does not cause any short-term health effects such as shortness of breath, coughing, headaches, or fever.

Research suggests that swallowing water with high radon levels may pose risks, too, although risks from drinking water containing radon are much lower than those from breathing air containing radon. For a more detailed discussion about radon health risks go to the EPA Citizen's Guide to Radon.

Radon testing

While radon problems may be more common in the upper piedmont and mountain counties of North Carolina, any home may have an elevated radon level. New and old homes, well-sealed and drafty homes, and homes with or without basements can have a problem. The only way to determine the level is to conduct a radon test.

In addition, indoor radon levels vary from home to home. Do not rely on radon test results taken in other homes in the neighborhood - even ones next door - to estimate the radon level in your home.

Do-it-yourself Radon test kits that meet EPA requirements are available for $10 in Environmental Health.

Testing your home for radon is as simple as opening a package, placing a radon detector in a designated area, and after the prescribed number of days, sealing the detector back in the package and mailing it to a lab for evaluation. Radon is measured in picocuries per liter of air (pCi/L), a measurement of radioactivity. The US EPA and the Centers for Disease Control and Prevention recommend that homes with radon levels at or above 4 pCi/L be repaired to reduce the amount of radon entering the indoor air.

You may also have a certified radon service professional conduct the measurement in your home. It is highly recommended that anyone having their home measured or mitigated for radon have it done by someone that is certified by either the National Environmental Health Association (NEHA) or the National Radon Safety Board (NRSB). The Environmental Protection Agency (EPA) recognizes these two agencies for certification purposes. While North Carolina has no laws concerning radon other than a radon disclosure law in real estate transactions, other states may. Be sure and check with your State's Radon Contact for this information.