Researchers estimate that we spend 22 of the 24 hours in a day, more than 90% of the day, in an indoor environment. (Wu 2007, 953) As such, it is not surprising that the indoor environmental quality (IEQ) can have a significant impact on our health, and it has been known for centuries that contaminants in the indoor environment can reach levels that are dangerous to health and even to life. (Morawska 2008, 5)

The relationship between the built environment and health effects is very complex (Wu 2007, 954), but our understanding of the relationship is evolving. Acceptable indoor air quality was once defined as "air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which a substantial majority (80% or more) of the people exposed do not express dissatisfaction." (ASHRAE, 1989) When that definition was in vogue, investigators were primarily concerned with indoor air constituents and comfort factors. However, today's IEQ investigators understand that there is a complex interplay between a building's occupants (who they are and what they do) and a wide array of physical, chemical, biological, and design factors. (Mitchell 2007, 958)

It is the IEQ investigator's job to determine what hazards exist in the built environment and the sources of those hazards. The potential hazards in the built environment include particulates; chemical, biological and physical agents; and psychological factors. The sources of hazards can include the building's design, envelop, mechanical systems, and furnishings; products used; occupant activities; and even external sources. (Wu 2007, 954)

When one steps out to conduct an IEQ investigation, one is never sure what all the investigation will entail. The process of the investigation is well known and is flow charted in Exhibit 1, but the actual tools that will be required "to collect additional information" are always uncertain at first. In my 20+ years of investigating IEQ complaints, I've seen sources and hazards that have run the gambit from simple and obvious to complex and elusive. But every investigation has required the use of IEQ tools to validate my hypotheses. Some investigations have required just a few simple tools and others have required every IEQ tool in my arsenal, and then some. This paper will examine the tools commonly used to conduct an IEQ investigation.

(Exhibit in full paper) Making "Sense" of the Tools

One of the very first tools used to measure IEQ contaminants was the canary. Carbon monoxide is an inherent threat in underground mines, but in the early days of the mining industry there were no instruments to warn of dangerous levels of this odorless, colorless, and tasteless gas. So, cages of canaries were hung throughout the mine to act as "indicators". The birds were particularly susceptible to carbon monoxide and, if one died, it was a warning to leave the mine. (Morawska 2008, 5) Thankfully, today we have much better tools and methods for evaluating the indoor environment and for measuring contaminants.

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