FAIRBANKS — Q: How do you know if your indoor air quality is good? 

A: One upside of all the rain is a relatively smoke-free summer in Fairbanks. But air quality is still an issue we deal with throughout the year. In the winter, the borough provides constant updates on air quality, as inversions combined with wood smoke can create high levels of particulate matter in the air. In the summer, forest fires produce poor visibility and bad air quality, which endangers those with heart and lung problems.

Yet, we don’t hear very much about the quality of our indoor air, despite spending most of our time indoors. What does good indoor air quality mean? And how do you know if the air quality inside your own home or office is good? 

Scientists use a number of markers to rate indoor air quality, many of which will be familiar. Among the most common are humidity and temperature.

Although temperature is largely a matter of individual preference, humidity is more a matter of health and safety. Humidity levels should balance what is healthiest for the house and what is healthiest for the occupants. Levels between 40 percent and 60 percent are best for people, yet this much moisture is stressful for buildings in the cold, dry climate of Fairbanks. Therefore, the rule-of-thumb is to keep humidity levels below 30 percent in the winter to reduce the risk of mold growth. You achieve this through bathroom fans, range hoods, heat recovery ventilators (HRVs) or energy recovery ventilators (ERVs).

Carbon monoxide (CO) is a deadly gas produced by fuel combustion appliances, such as boilers, furnaces and cars. It’s especially dangerous because it cannot be smelled or seen by humans. Symptoms of low-level carbon monoxide poisoning include headaches, dizziness and nausea; in higher levels, it causes confusion and even death. 

To keep CO out of a home, heating appliances should have sealed combustion chambers that vent directly outside and homes should have CO alarms to alert occupants of any problems.

Carbon dioxide (CO2), on the other hand, is produced when we breathe and is only dangerous at extremely high levels. 

However, higher levels of CO2, such as those that result from a large number of people in an unventilated room, cause drowsiness and a general feeling of stale air. Also, it is helpful to watch CO2 levels as they are a good indicator of air quality and ventilation levels — if it’s accumulating too quickly, it’s likely other gases will be high, too.

VOCs, or volatile organic compounds, are emitted from cleaning supplies, beauty products, air fresheners, scented candles and types of cooking. They also leak off of certain types of paint and furniture. They can irritate the nose, eyes and throat, and cause headaches at lower levels. Formaldehyde and benzene are of particular concern since chronic exposure can contribute to cancer risk.

Ventilation is one strategy to reduce VOC levels; a second strategy is through source control — research cleaning products, paint, building materials and furniture to find types that don’t off-gas. Increasing ventilation when VOC-producing products are used also helps — for instance, turning on the bathroom and kitchen fans when cleaning.

Particulate matter includes dust, smoke particles, pollen and other small particles that float through the air. Indoor particulates come in through open windows, air leakage through the envelope, ventilation systems or are carried in on people’s clothing. 

Some are also generated indoors, such as from cigarette smoke, wood stoves, candles and cooking. Vacuuming with an unfiltered vacuum can often release particulates from the floor into the air. Particulates come in different sizes, and the smaller the particle, the more dangerous it is to health. PM 2.5 is of particular concern because it is known to cause severe health complications. 

You can take several steps to ensure good indoor air quality. First and foremost, install a carbon monoxide detector. Available for $20 at grocery and construction stores, it can save your life. In fact, they are required in all residences by Alaska law AS 18.70.095. They should be installed in bedrooms, in hallways near bedrooms, just outside of attached garages and mechanical rooms with combustion heating appliances and in kitchens with natural gas stoves.

Second, make sure your bathroom fans work and use them when bathing. It’s a good habit to check the outdoor vents a couple times a year, which can be blocked by ice or debris. Kitchens should have a range hood ducted to the outdoors that can be turned on while cooking — and again, checking the outdoor vent for blockages on a regular basis will ensure it is working properly.

Finally, look at your windows during the winter. If you see condensation on the window, your indoor humidity is probably too high and you should use your exhaust fans in the bathrooms and kitchen. If problems continue, seek professional assistance from a ventilation contractor. Also, join us for a building tour of CCHRC’s research center on the second Thursday of each month to learn more about indoor air quality and ventilation strategies.

The “Ask a Builder” series is dedicated to answering some of the many questions Fairbanks residents have about building, energy and the many other parts of home life.

Ask a Builder articles promote home awareness for the Cold Climate Housing Research Center (CCHRC). If you have a question, contact us at info@cchrc.org or 457-3454.