Human senses include smell, touch, sight, and hearing. A healthy indoor environment includes at least four senses: indoor air quality, thermal comfort, illumination, and acoustic comfort. This article begins a discussion of the first sense: Indoor Air Quality.

Indoor air quality is complicated. It is best described as a perception, which is annoying to some and pleasing to others. In some cases, it relates to serious health effects for some but yet does not affect others.

Our indoor air quality discussion will include at least two aspects: odors and allergens. This article discusses odors. A future article will discuss allergens.

Indoor environments include many different odors. Some odors are pleasing. A cook takes delight in the smells of cooking. Fresh flowers offer pleasing fragrance.

Some odors are offensive. Spoilt food odors can be nauseous. Cleaning chemicals are irritating. Moldy odors are worrisome. Sulfurous odors are alarming.

Household odors represent many different sources. Each of us reacts differently to this odor cacophony.

Our sense of smell protects us from harm. Smell reveals conditions that are not otherwise evident. We become aware of good as well as danger. We associate some odors with safe food and secure conditions. We associate other odors with bad food and harmful conditions.

We smell (detect) odors at concentrations as low as one part per billion. Usually it takes a somewhat greater concentration to recognize (identify) an odor.

Our ability to first detect an odor is inherent, just as some people are short and others are tall; hence, some people smell an odor and others smell nothing. Our ability to identify odor is based upon association with individual experience; hence, one person describes an odor one way and another describes the same odor another way.

Odors are airborne contaminants; pure air is odorless. Because human sense of smell is so sensitive (low parts per billion), many common measurement meters cannot detect contaminations that are detectable by the human nose.

Airborne contaminants travel with air movement. Sometimes an odor is detected in the vicinity of the odor source; example, space within a cabinet or closet. Often air movement carries odors from sources within hidden spaces into living spaces; example, moldy odor from mold growing within a wall traveling into living spaces.

Investigating problem odors usually requires building diagnostics. Odor investigations can include multiple approaches:

• Understanding what-when-where the odor is present can allow an experienced investigator to identify prospective odor sources.
• High sensitivity meters can detect many volatile organic and formaldehyde in part per billion concentrations. Laboratory analyses can further identify many chemicals. Once detected or identified, chemicals can be associated with prospective household sources.
• Airborne mold spores can be readily measured. Moldy odors can travel through wall and ceiling spaces; in which case, prospective moisture sources suggest the mold growth source.
• Air movement patterns can frequently be identified with a smoke tube, an infrared camera, a blower door, or a combination of these techniques. Air flow pathways suggest prospective odor sources.

Your sense of smell detects the healthy and the harmful. If a home odor is questionable or offensive, the odor represents poor indoor air quality. Such odors may be associated with a harmful condition!

Your nose is a legitimate gauge of indoor air quality. Listen to your nose!

… because healthy air matters!

Filed under: Building Diagnostics, Green Homes, Indoor Environment Quality