What is Indoor Air Quality and how does it affect me?
Indoor air quality, or IAQ, encompasses many aspects of a healthy, comfortable atmosphere: temperature, humidity, and the amount of pollutants such as carbon dioxide, radon, volatile organic compounds and particulate matter. The IAQ of homes is receiving lots of attention these days because houses are being built more airtight and better insulated than ever before. While this means they’re using less fuel, it also means they’re getting less ventilation through passive air leakage to moderate airborne pollutants in the home.
Two factors that play a huge role in our health and comfort are temperature and humidity. While temperature is usually regulated by the heating system, humidity is less controlled. Water vapor is produced by daily activities such as breathing, cooking, and showering, and can also come from houseplants and soils in crawlspaces. A certain amount of humidity is good (30-40 percent is recommended) because it keeps our skin and sinuses from becoming overly dry, stops static build-up and benefits people with asthma or respiratory issues. High humidity, however, can cause problems for the house and its occupants. In a place as cold as Interior Alaska, humidity levels above 40 percent in winter can lead to condensation within the building envelope, which promotes the growth of mold, mildew and rot, and humidity above 60% sets the stage for bacteria, viruses and fungi, no matter what time of year.
Pollutants are introduced into a house in many ways. Carbon dioxide, produced when we breathe, is often used to gauge the “freshness” of indoor air (or the air exchange rate). Carbon monoxide is a dangerous gas produced by combustion heating appliances, gas ranges, and cars. All homes should have a CO alarm near any bedrooms. Pollutants that can cause irritation or long-term health problems originate from materials in or around our homes, such as formaldehyde, which can be released from carpet, cabinets, and furniture, or radon, which is released from certain types of soils underneath a home’s foundation. Other bad pollutants can be generated by smoking, cooking, and chemicals used for cleaning or pest control. Many can irritate eyes, cause headaches or fatigue, and trigger asthma symptoms. Long-term exposure can increase the risk of cancer and respiratory disease. Because we spend so much time in our homes, maintaining good air quality is key to staying healthy.
How can I improve IAQ in my home?
Ventilation is one of the most important steps you can take. This can take different forms. Local ventilation should be provided for high-pollution areas like kitchens and bathrooms in order to remove pollutants before they migrate to other areas of the house. This typically entails exhaust ventilation, such as range hoods and bath fans, devices that can be controlled by switches or run on a timer and serve to exhaust pollutants and excess humidity.
There are also systems that provide either supply air and exhaust air, but not both. For example, an exhaust-only system usually consists of one or more bathroom fans designed to run continuously. Fresh air must enter through leaks and cracks in the building envelope, which is not an ideal situation. In a supply-only system, a central fan is typically integrated into a forced air distribution system to bring fresh air into a home. Supply-only systems are not recommended in Alaska since they force moisture from inside the house into the building envelope.
The best type of ventilation in an efficient home is a whole-house system that runs continuously and balances supply and exhaust air so the house doesn’t become pressurized or depressurized. A heat recovery ventilator (HRV) or an energy recovery ventilator (ERV) get rid of stale air and provide fresh air at an equal rate, distributing it through the home through a ducted system.
No matter what the ventilation strategy for your home, make sure it’s working properly and that outdoor air vents are open and unblocked.