The Good Air Lady
The Good Air Lady
talks about what you breathe
indoors and out

Air Quality Instruments

Air quality instruments are for those with health concerns. You need to measure indoor air quality to determine what actions you need to take to improve the air quality. Air pollution is a common concern, but there are other environmental concerns to pay attention to as well, like temperature, humidity and radon levels.

"What gets measured gets attention" is the philosophy behind everything from your car's gas gauge to public education and indoor air quality control. Schools call the achievement tests they administer "instruments". Health and energy conservation-minded consumers need air quality instruments. This article looks at what to measure and what instruments are available to measure it.

Temperature is the most commonly measured indoor air quality. Thermometers are essential parts of all thermostats used for indoor air quality control. Analog thermometers rely on the expansion or contraction of a coiled spring to measure temperature changes. The moving spring can also trip an electrical switch that turns heating and cooling machinery on or off. Digital thermometers and thermostats use changes in a material’s electrical properties. Thermocouples found in inexpensive digital thermostats are accurate only to within 1.8 degrees F, allowing a room to be wastefully over- heated or cooled by nearly two degrees! Thermistor-based thermometers and thermostats are much more precise and respond faster to temperature changes, so they use less energy to maintain a room’s temperature at a comfortable level.

Humidity is another critical indoor air quality. Water loses or gains heat more slowly than air, so more humid air requires less energy for cooling or heating to maintain a comfortable temperature. Humidity also affects the health of skin, nasal passages, and lung linings. A relative humidity index of 40-60% is considered comfortable indoor air quality. The indoor air quality instrument used to measure humidity is called a hygrometer. Analog hygrometers actually measure the expansion and contraction of human or animal hair. Digital hygrometers measure electrical capacitance or resistance. The most accurate indoor air quality hygrometers include thermometers, because relative humidity must be calculated relative to temperature. Naturally, they are more expensive than hygrometers without thermometers, which “assume” a constant "room temperature" of about 72 F.

Allergens are an important indoor air quality to measure, even if you think you don't have any allergies. Undiagnosed, low-level allergic reactions are responsible for a lot of unexplained fatigue, sleeping difficulties, and respiratory infections. Air quality instruments for measuring airborne allergens are prohibitively expensive for home users. But air quality testing services to which one can send samples of indoor air are available; ask your doctor for a referral.

Toxic gases, including carbon monoxide, carbon dioxide, and radioactive radon affect indoor air quality to varying degrees. Air quality instruments to measure concentrations of these gases are available at many home improvement stores. Carbon monoxide and dioxide detectors, which sound an alarm if gas concentrations rise too high, are advisable in homes that are sealed tightly, year-round or only in winter months. Test your home's cellar or basement for radon using an inexpensive do-it-yourself it, and install a radon alarm air quality instrument if there is any doubt that radon levels may rise.

Measuring indoor air quality is the first step in making and keeping your home or office a safe and comfortable place to live.