Things stink/smell/have an aroma for a reason. Whether it is pleasant, like the fragrance of a rose, or unpleasant, like vomit or fecal material, everything which gives off an odor is emitting tiny microscopic pieces of itself into the air. Those tiny pieces - in incredibly small amounts - are caught in the nasal passages where their DNA is read by the olfactory nerves and checked in the brain against a memory bank of some 10,000 substances to determine what the appropriate response should be. It is not by accident that substances which have a universally recognizable foul odor are known to be harmful to us. Their telltale odors are a fairly sure sign for us to avoid them. This emission of molecules by a substance is similar, by illustration, to the way that humans lose skin cells. We do not lose our entire epidermis, at least not all at once, but shed instead those dead cells closest to the surface of our skins. In like manner, all things aromatic "slough off" or emit microscopic pieces of themselves throughout most, if not all, of their existences. The rates at which this emission occurs from a substance is dependent upon the ability or lack of ability of the mass of the matter to retain those molecules furthest from the center of the mass and closest to the surface - where they tend to break free of the chemical bonds which hold them together and take flight into the surrounding air. This phenomenon is called "off-gassing", and the measure of the rate at which it occurs is the measure of its "volatility". Depending upon the nature of the substance itself, the product of the off-gassing will be either benign or toxic. (See "VOC's" next.) A further consideration is the fact that a substance en masse or as a solid may not pose a health risk, yet the emitted molecules may, because as a solid substance the product is not inhaled, but the gases or emitted molecules are. Our response to offensive odors in our homes and workplaces is usually to cover them up by overwhelming our smell mechanisms with fragrances we prefer over those we do not. We use potpourri, scented candles, air sprays, carpet and upholstery sprays, closet hangers, outlet puffers, pet sprays, and a rising proliferation of room deodorizers and air fresheners of varying sophistication - to the tune of upwards of $3 billion annually. Consider also that one can hardly take a bath or shower, shampoo the hair, wash the hands, wash the dishes, flush the toilets, clean house, or process the laundry without adding still  more of these cover up perfumes. Unfortunately, tricking our noses into thinking that everything smells pleasant does not do away with the fact that the sources for the unwanted odors remain active and productive and continue to cause harm to our bodies when they can. And the rising use of fragrance enhanced products is now causing people to develop perfume sensitivities and allergies for which many are seeking medical attention.

What You Need to Know
(A brief Overview of Indoor Air Quality Issues)
IAQ Overview - Table of Contents
IAQ Overview - Part 1 - Is There a Problem?
IAQ Overview - Part 2 - What Don't We Know?
* IAQ Overview - Part 3 - What Do We Need to Know? *
IAQ Overview - Part 4 - Which Technology Works the Best?
IAQ Overview - Part 5 - What are the Major Differences in the Technologies?
IAQ Overview - Part 6 - What IAQ Issues Need to be Considered and Addressed?
IAQ Overview - Full Article