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 continues a discussion of the first sense: Indoor Air Quality.

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

An earlier article regarding indoor air quality discussed odors. This article discusses another aspect of indoor air quality: allergens.

Chemicals can also cause health effects. These chemical-caused health effects can be quite different from the health effects caused by allergens. A future article will discuss yet another aspect of indoor air quality: chemicals.

[Please note that I do not pretend to understand fully the distinctions between allergy and asthma, let alone the various mechanisms that cause various allergic responses. However, allergens are too important for us not to attempt to understand and control thier sources within our homes.]

Allergens cause some persons to have allergic reactions, while others are completely unaffected. Most individuals who have severe allergies – especially asthmatics – know their condition and the allergen sources that trigger reaction.

Allergies and asthma are similar in that both are triggered by allergens. Asthma causes inflammation and swelling in the lower respiratory passages (bronchial tubes), which narrows the airways and causes breathing difficulty.

About eleven in one hundred people suffer from some form of allergy. Three of these sufferers are asthmatic.

Allergic reactions can affect nasal membranes, eyes, skin, tongue, and breathing passages in severe cases. Allergy symptoms include an itchy, stuffy, or runny nose, sneezing, itchy, red, or irritated skin, and itchy, burning, or watery eyes.

Allergens can include almost any air pollutant. Most allergens are very small particles, although some are gases. Examples of particles are mold (dead or alive), pollen, pet dander (dogs, cats, birds, reptiles), insect and pest droppings (dust mites, cockroaches, rodents, lizards), food, and smoke. Examples of gases are chemical vapors, including fragrances, combustion soot, cleaning solvents, adhesives, and paint products.

Common Sources

Household Dust. Household dust is a term that describes the ubiquitous debris that accumulates on surfaces and floors within our homes. Since we have cats and dogs, our house dust usually resembles a fur ball; which my kids call dust muffins. Whatever house dust looks like, it is potentially a bouillabaisse of allergens that enter into, or are created within, your home.

Mold. Mold is often blamed for allergic reactions. The Center of Disease Control studied building environments with known indoor air quality complaints. Correlation was found between damp buildings, mold, and complaints (Facts about Mold and Dampness). Further, the media has engrained the notion that Toxic Black Mold is surely the root of all indoor environment evil.

My experience is that many people asking for help for their sick homes firmly believe that mold is causing their discomfort. Their first words are “Test my house for mold!” Mold testing can be expensive ($600 to $2000). I do not recommend mold testing unless there is a known or suspected moisture source or there is a musty odor.

If mold is visible, testing has limited value other than to indicate whether airborne contamination is spread. Testing is more useful after mold-damaged material is removed (remediation). Post-remediation testing verifies that air quality is normal.

Dust Mites. Dust mites are the most common cause of allergy from house dust (House Dust Allergy). They prefer temperatures at or above 70 degrees Fahrenheit with a relative humidity of 75 percent to 80 percent … such as in South Florida.


The good news is that dust mites are easily recognized under a microscope. They look like sci-fi monsters. Carpet and bedding samples are easily collected and viewed under a microscope (400x). Filter samples can be laboratory tested (Allergen-ELISA screen) to confirm the presence of dust mite allergens, as well as allergens associated with pets and cockroaches.

Control
Controlling allergen exposure in our homes relies largely upon eliminating or mitigating prospective sources. For example: tile or wood flooring is better than carpeting; no pets is better than pets; no candles or fragrances is better than ad hoc aroma therapy; humidity control is essential.

Particles. As mentioned earlier, many – if not most – allergens are very small particles (less than 100 microns. HEPA filters (MERV 16) remove 99.97% of particles as small as 0.3 microns. Most mold spores are larger than 1 micron. Most pollen grains are larger than 20 microns. HEPA filters can remove airborne mold spores and pollen grains from your home.

Installing a HEPA or near-HEPA filter in your air handler provides whole removal of allergen particles. Further, equipping your vacuum cleaner with a HEPA filter further removes allergen particles. Vacuum cleaners with standard filters actually disperse, rather than remove, small particles.

Gases. Allergen gases are tougher to remove. Your best bet is to avoid generating potential allergens that are gases: Do not use aromatic candles or deodorizers; consider fresh air ventilation to pressurize your house with respect to your garage, attic, and the outdoors.

If you have allergies – especially if you are asthmatic – you probably already know what can hurt you. If your condition is severe, you probably have taken measures to protect your home environment.

If you are uncertain, trust and listen to your body … because healthy air matters!

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