Single Pass Test: UV Deadly for Airborne Microbes
This study introduced a common bacterium into a galvanized air duct equipped with a UV light to determine how effective the lamp would be in reducing the bacteria with one exposure, or a “single pass.” The tests were conducted at two speeds: 1125 cfm and 2250 cfm in an 18" x 18" duct. The UV lamp yielded at least a 90% reduction of the test bacteria with a single airflow pass at 1125 cfm, and at least 71% reduction at 2250 cfm.
Cumulative Tests: Multiple Exposures Dramatically Improve IAQ
To further investigate the effectiveness of UV on indoor air quality, Microbe Management created a series of tests designed to measure the cumulative effect of UV in reducing airborne contaminants. The tests were performed in a structure with two isolated 8' x 8' x 8' rooms where air could be sampled. In the control room, no UV was present, while the other room utilized a portable UV air purifier. According to Bernard Kane, Ph. D., of Microbe Management, “Test results were very encouraging. In both rooms, we introduced a resistant, spore-forming bacteria until the air was saturated with 350 colonies per cubic foot. In the room with the portable UV unit, the spore count was reduced by 50% in just 10 minutes and by 98% within 30 minutes. In the control room, without UV, more than 85% of the bacteria were still active after thirty minutes.” Similarly, the leading consumer UV “tower” model was also tested, but showed only minimal effectiveness. (See chart below.)
Conclusion: UV Is An Effective Part of “Whole House” Solution
A-coil irradiation, single pass, and cumulative tests confirm that UV is an important and effective contributor to a healthier home environment. UV technology used with a quality filter (MERV rated 8 or higher) will dramatically improve Indoor Air Quality. Additionally, portable units can be used in combination with in-duct models. This combination is strongly recommended for individuals with depressed immune systems, asthma, allergies, or other respiratory conditions. For homes without forced-air, portable UV air purifiers are recommended to enhance IAQ. Also, health care professionals, teachers, and day-care workers can benefit from additional UV protection from influenza and other viruses.