Indoor air quality (IAQ) may affect occupant comfort, productivity, and most importantly health. Good IAQ will contain relatively low levels of carbon dioxide, carbon monoxide, odors, volatile chemicals, dusts, and harmful microbes. In fact, temperature, humidity, and outdoor make-up air should be kept within a certain range to provide a comfortable working environment for the occupants.

As mentioned, poor IAQ may affect occupant health. Some of the more common symptoms of poor IAQ are: cough, irritation to mucous-membranes, headache, allergic reactions, dry or itchy skin, dizziness, nausea, fatigue and thermal discomfort. Periodic IAQ investigations should be performed to stay on top of potential IAQ issues. Responsive IAQ investigations should be performed following an occupant complaint or concern. Investigations should include measuring the following common IAQ parameters, depending on the situation:

• Temperature and relative humidity. The American Society of Heating, Refrigeration, and Air Conditioning Engineers recommend the air temperature in office buildings be maintained between 68 and 74 degrees Fahrenheit and the relative humidity be between 30 and 60 percent.
• Carbon dioxide. Carbon dioxide levels are an indication of sufficient fresh air supply and ventilation at the time of the survey. Criteria often cited are 800 parts per million (ppm) to 1,000 ppm, or about 650 ppm above outdoor air.
• Carbon monoxide. Results above 5 ppm indoors are considered excessive.
• Volatile or irritating chemicals. Acceptable indoor concentration depends on the individual chemical. Many chemicals can be detected by odors. Odor itself may or may not be an indication of a potential health problem; however, just the odor of some chemicals may cause uncomfortable conditions for selective occupants.
• Mold. The indoor mold level should be at or below the outdoor mold level. Mold types found indoors should be comparable to the types found outdoors.