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UV-C Air Purification


Q. What is UV-C light and how does it kill bacteria?

A. UV-C is the invisible, ultraviolet, C-band radiation that makes up part of the sun’s light spectrum. UV-C light prevents growth and germination of microorganisms by altering DNA and RNA and effectively sterilizing organisms. Once sterilized, they cannot reproduce, and with their short life cycles, they are effectively killed.

Q. Why use a UV light product?

A. There are two primary benefits to using UV light. The first is radiate a surface to keep mold from growing in that area. The other use is disinfecting the air stream as it passes through the HVAC system. A significant disinfection rate is accomplished with repeated circulation of air through the system.

Q. What is the importance of UV light products?

A. People spend over 90% of their time indoors. With little or no ventilation, concentrations of microorganisms will increase indoors, potentially spreading a number of diseases. With increased cases of deaths being caused by various bacterial diseases, controlling the growth and spread of pathogens is of major concern in indoor environments.

Q. Is the product suitable for people with severe allergy or asthma problems?

A. Yes. The UV-Aire can offer relief to many allergy and asthma sufferers by reducing airborne contamination.

Q. Does the UV-Aire produce a fresh-air smell?

A. Many smells are not addressed by the UV-Aire. However, some unpleasant smells develop from the growth of microorganisms. The UV-Aire works to reduce mold and common household germs, in many cases resulting in a fresher smelling environment.

Q. Does UV light take the place of a filter?

A. No. The UV-Aire should be used in conjunction with a filter.

Q. Should the HVAC appliance fan or blower run continuously?

A. No. During normal operation of the heating or air conditioning, the blower will circulate the air over the UV lamp from 40-75 times a day, which is sufficient. During moderate weather, when neither the A/C or heat is on, it is recommended to open the windows to allow for fresh air infiltration and/or to operate the blower continuously (turn on the fan) to circulate air over the UV light.

Q. What precautions should be taken before opening or servicing the ductwork where a UV-C lamp is in use?

A. The UV-C lamp should be turned OFF prior to entering the ductwork. An external switch is provided as well as warning labels regarding service procedures. Direct exposure to UV light is not recommended, as it may cause damage to skin and eyes. Protecting the eyes with plastic protective goggles is recommended.

Q. What effects will UV-C rays have on plastics such as coil pans & flex duct?

A. If the plastic is not UV resistant, UV-C can cause a breakdown of the material over time. Based on lab tests, positioning the lamp 30 inches or more away from plastic surfaces will eliminate any measurable breakdown of plastic material.


The Whole House: Air Purifying System

Indoor Air: High Concentration of Biological Contaminants With tighter building construction in recent years, the quality of indoor air has declined dramatically. The air circulating in the ductwork of the average home or office can be concentrated with contaminants including molds, bacteria, and viruses. We fill our lungs up to 20,000 times each day. Over time, these contaminants can cause inflammation of the mucous membrane, upper respiratory problems, asthmatic conditions, headaches and flu-like symptoms.

The Sun: Nature’s Outdoor Air Purifier

For years, scientists have known that one of the most effective air purifiers is natural sunlight. Not the light we see when we look out the window, but the invisible “C” band, ultraviolet rays that make up part of the sun’s light spectrum. The sun’s UV-C rays act as a natural outdoor air purification system, inhibiting the growth and reproduction of bacteria, viruses, fungi and molds. However, this natural process does not occur indoors. Ultraviolet germicidal radiation replicates the natural outdoor purification system of the sun by destroying the illness and diseasecausing microbes living and multiplying in indoor air. In combination with a quality filter, it is the most effective way to reduce airborne bacteria and the health risks they represent.

Since direct exposure to UV light can cause skin cancer and blindness, the most practical application is to install UV in the main supply or return duct of any central heating or cooling system. This is an ideal location since the air in the home or office will pass through the HVAC system 40-75 times a day during normal operation and as many as 150 times a day in continuous fan mode. UV’s effectiveness is directly related to a microorganism’s exposure time.

Filter Systems Alone Can’t Solve the Problem

The majority of indoor air is conditioned by forced-air heating and cooling (HVAC) systems. HVAC systems are a dark and damp breeding ground for mold and bacteria, particularly at the filter and air conditioning coil. The buildup of matter on the A-coil and filter can significantly reduce the efficiency of the appliance by constricting and reducing air flow. This means increased cost to the homeowner in addition to the risk of airborne pollutants. Air filters are a great first step, but are ineffective in trapping germs, as most particles are simply too small, passing through the porous filter. UV-Aire, in combination with a quality filter, turns any forced-air HVAC system into a whole house air purification system.

How Effective is UV for Air Purification?

For many years, ultraviolet light has proven effective in sterilizing medical equipment, purifying water and processing food. Currently, the use of UV lights is gaining industry acceptance in HVAC applications. Microbe Management, Inc., a testing agency in Greenville, NC, has conducted three separate tests to examine UV’s effect on indoor air quality. The test results reviewed in this article conclude that UV is an integral part of a whole house approach to improving Indoor Air Quality.

Attack the Source

While experts disagree on the root causes of many IAQ problems, there is consensus that stopping problems at the source is crucial to long-term air quality improvement. First, the homeowner must eliminate any unwanted sources of moisture in the home such as roof leaks and drainage problems. Likewise, the air conditioning coil must be addressed since it is a natural breeding ground for molds, which thrive in a dark, moist environment. Familiar with the rank smell generated when switching from air conditioning to heat mode? That is the smell of mold and bio-film burning off the coil. Whenever the blower is engaged, mold spores from contaminated A-coils are released into the ductwork and distributed throughout the building. These spores then seek alternative surfaces in other parts of the home to breed and multiply.

Surface Test: UV Kills and Prevents Mold on A-Coils

A specific test was designed to determine UV’s effectiveness in treating mold on coil surfaces. The test simulated the damp, dark settings where A-coils are found. In this study “We took a standard A-coil, sterilized it, introduced two kinds of mold and then placed it in a controlled, moisture-laden environment,” says Bernard Kane, of Microbe Management. “We created two separate chambers in our lab. One chamber was bathed in UV light. The other was not.” The results were dramatic and conclusive. The side of the A-coil that was exposed to the ultraviolet light was clean and clear of mold growth. Mold continued to grow unabated on the side without UV. Subsequently, the contaminated side was bathed in UV light and the mold was eradicated. Kane summarized the results:

"Properly positioning a UV lamp over the A-coil in a residential or commercial air conditioning system can eliminate surface mold on the coil and prevent future mold growth as well."

Airborne Testing: Single Pass and Cumulative Tests

Bacteria and viruses are introduced into the building by its occupants and often cannot be controlled at the source. Therefore, it is important to attack these airborne invaders early and often, before they have an opportunity to multiply. The single pass test proves that UV effectively kills these airborne microorganisms in the duct. Since HVAC systems typically re-circulate the air 40-75 times per day, a multi-pass, cumulative test was also conducted. Results demonstrate that repeated, multipass exposure to UV light dramatically reduces the concentration of bacteria and viruses throughout the home.

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 Test: 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 test was 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.

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.


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