Each and every day your lungs process up to 1000 cubic feet of air, or the equivalent of 30,000 quart containers per day. I am sure that seems like a lot of air, but read on for additional interesting information.

Asthma, allergies, and airborne diseases are triggered by the repeated exposure of the lungs to small doses of chemical substances. Airborne contaminates cause diseases such as Influenza, Hepatitis, Tuberculosis, and Pneumonia, to mention only a few.

Asthma and allergy sufferers are extremely sensitive to contaminants such as dust, pet hair, mold spores, odors (chemical and biological), bacteria, and second hand smoke.

The human body "part" with the largest surface area exposed to the air is not our skin, (which represents about 20 square feet of surface area), but is in fact our lungs with their complex alveoli network covering a surface area greater than one third of a football field.

Studies have shown that the air inside our homes and businesses can be in excess of 100 times more polluted than the air outside.

Viruses and bacteria find their way into our bodies either orally, by inhalation, or by penetration through the skin and mucous membranes. 65-75 percent of infection and allergy sources are passed from person to person by one of these three methods.

What can we do to combat health hazards found in the air? Let's start by briefly discussing air filters. Air filters clean solid particulates from the air. Filter capabilities range from poor to very good. By poor I mean the standard inexpensive glass fiber disposable filter does a decent job of trapping "golf balls" size particulates, but a very poor job on anything much smaller. Actually, glass disposable filters only become an efficient filter when they are dirty. The other end of the disposable filter scale is the HEPA type with its 99.9% filtration capability. This terrific filter is used most frequently in OSHPD and medical buildings, but it's impractical for every day residential and business use. The HEPA filters are so efficient at trapping the smallest particles that moving air through it is like trying to blow air through a concrete wall. Very few HVAC units have the design capability to work under these conditions, and so require an additional duct booster when used with HEPA filtration systems.

For our mobile/modular industry purposes, the simple upgrade from the 1" glass disposable filter ($ 1 cost) to a 30% 2" pleated filter ($ 8 cost) makes sense. A 30% 2" pleated filter will collect particles down to the 10-micron size. Pleated filters provide additional surface area with which to collect particles. It is disposable, also. 

Washable filters do not seem to be as workable in the mobile/modular industry. If there is any doubt about that fact, consider the following.

How, when and where will the ··filter get washed?

By Whom? The Occupant? The ··Dealer?

Do the Occupants know how to ··clean the filters properly?

Did the washed filter come out ··clean?

Again, there are many other filters available on the market for your examination, and proper industry application, but the 30% 2" pleated filter seems to be the easiest, proven upgrade from an inexpensive glass disposable filter.

While air filters remove harmful solids, Ultra Violet lights are used to purify the air of chemicals and biologicals. Sunlight is the most effective natural air purifier known to break down chemical and biological contaminants. UV lights work in a similar fashion, through both UVV and UVC capabilities. What are Ultra Violet light UVV and UVC outputs?

UVV destroys chemical contaminants (solvents, formaldehyde, VOCs) by photo-oxidation. UVC destroys biological contaminants (yeast, mold, bacteria, virus) by destruction of the organism's DNA. Since airborne living organisms have short life spans, their population decreases rapidly when reproduction is inhibited by UVC.

Ultra Violet has proven effective in the water treatment, and pool/spa industries. You may have a pool filter with a UV light in a 2" diameter pipe to control the bacteria and algae of your pool. In water treatment systems we can actually see the results. Shut off the UV light and watch the algae grow. It is different in air treatment because it takes expensive testing equipment and procedures to "prove" the air is cleaner with the use of a UV light. We can only see the results in the air testing agencies documentation.

Another interesting fact about UV air purification systems is that efficiency decreases farther away from the bulb. This decrease occurs very quickly and is not linear. The "kill" rate is 100% right next to the quartz UV bulb, 60% efficient .40 inch from the bulb, 40% efficient 1 inch from the bulb, and 20% efficient 2 inch from the bulb. While this mere 20% efficiency at only 2 inches from the bulb may concern you at first, remember that the air should be constantly circulating. An air filter, and your pool filter take more than one pass through to clean the air or water. The same is true for UV systems.

To get the most from your UV system, it is important to use a UV light that has both UVV and UVC capabilities. UV bulb manufacturers normally use two different types of quartz glass in the bulb: approximately 20% for UVV and 80% for UVC capabilities. The life expectancy of a UV bulb should be about 12,000 hours of run time. If the blower were run 24 hours per day, the bulb life span would be approximately 15 months.

We have just taken a quick glimpse into the world of air filtration and purification. Remember your home or business environment is like the analogy of a fish bowl or aquarium. We must do something to clean/purify the green stuff growing on the glass, floating around in the water, and/or laying on the bottom of the aquarium. This should help you visualize the hazards of an unhealthy breathing environment in your homes and businesses.

Well, I guess it's time to take Homer the fish out of the aquarium and change the water. It's starting to look a little murky in there! 

So inspect/change your air filter, update your knowledge on UV and other IAQ issues, and breathe a little easier until the next time we meet in . . . The Comfort Zone.

Copyright © Modular Building Institute, March 2000.