Taking the Mystery Out of UV Air Purification

January 31, 2003

The U.S. Environmental Protection Agency's (EPA's) studies of human exposure to air pollutants indicate that indoor levels of pollutants may be two to five times--and occasionally more than 100 times--higher than outdoor levels. For many dealers, it is a natural progression from improving a home's water quality to improving its air quality. Ultraviolet (UV) air purification is both a simple and cost-effective option for many consumers. Alone or combined with other technologies, UV can help address many of the concerns consumers have about their home's air quality.

When most people think about air pollution, they think about the air outdoors. However, the air quality in many people's offices and homes is significantly worse than the air outside. The U.S. Environmental Protection Agency's (EPA's) studies of human exposure to air pollutants indicate that indoor levels of pollutants may be two to five times--and occasionally more than 100 times--higher than outdoor levels. In fact, indoor air pollution can have a more significant effect on health because most people spend about 90 percent of their time indoors.

More than 15 million Americans have asthma, with the largest growth in children under five years old. In addition, consumers are becoming more aware of the significant health risks from mold in their homes. There is rising concern about indoor air quality. Clearly, an opportunity exists for water treatment dealers to expand their product offering to include air purification.

For many dealers, it is a natural progression from improving a home's water quality to improving its air quality. Ultraviolet (UV) air purification is both a simple and cost-effective option for many consumers. Alone or combined with other technologies, UV can help address many of the concerns consumers have about their home's air quality.

Pollutants, Treatment Options

There are many sources of indoor pollution in the home--tobacco smoke, household cleaners, central heating and cooling systems (HVAC), humidification devices, building materials, pressed wood cabinetry and countless others. In addition, homes with low air exchange rates will have higher concentrations of indoor pollutants.

Much like water, there is no single air purification technology that will remove all contaminants. The most effective systems combine a variety of technologies to address a homeowner's specific air quality concerns.

The main air treatment options include the following.

  • Ozone effectively oxidizes the organic and inorganic contaminants that cause odors--tobacco smoke, bacon, new paint and carpet fumes.
  • High-efficiency particulate air (HEPA) filtration removes particulate pollutants such as pet dander, pollen and dust that can aggravate allergies.
  • UV inactivates a variety of microorganisms including certain bacteria, molds and viruses.

Unfortunately, there is no simple in-home test that dealers can offer homeowners to pinpoint specific air pollutant problems. Consumers can have their air tested, but it is an expensive option. No home is free of pollutants, however, and most could benefit from air purification.

The Science of UV Treatment

Both UV and ozone use light to purify air. By setting UV lamps to specific wavelengths, different results are accomplished.

A UV lamp set at 185 nanometers will produce a low concentration of ozone, oxidizing odors throughout the house. A UV lamp set at 254 nanometers will inactivate certain biological contaminants. At the 254-nanometer wavelength, the UV light becomes germicidal and alters the DNA of single-cell organisms, preventing their reproduction.

Many units use two UV lamps, one to make ozone and the other to "sanitize" the air. The homeowner's primary concern--whether it is odor, particles or microorganisms--will help you select the most appropriate system.

Room Units Versus Whole-House Systems

Many people already own room air purification units, particularly individuals with allergies or odor concerns. Room-treatment ozone and HEPA filtration units use a fan to suck in polluted air and release treated air. Their treatment capacities are limited, however, because they tend to pull in the air directly surrounding them and lack the power to distribute treated air beyond a relatively small radius. Room-treatment ozone units also can pose a health threat if too much ozone builds up in a room. These units also can be fairly pricey.

A whole-house system, typically attached on the return side of a home's HVAC system, has the ability to treat and distribute significantly more air. It also allows for more distribution and control of ozone at safe levels. UV, which uses high-frequency light to kill microorganisms, is available as a whole-house treatment option. Compared with the cost of room units, whole-house systems offer tremendous value.

The one disadvantage of whole-house treatment systems is that they require a "closed loop" to be most effective. Therefore, in areas where homes are heated and/or cooled the majority of the year, a whole-house system is an outstanding investment.

Installation and Maintenance

Once you've worked with the homeowner to select the correct system, the rest is fairly straightforward. Installation is simple, compared with water treatment technology.

Several factors impact a UV unit's ability to work, including the following.

  • Amount of time the air is exposed to the light.
  • Distance the treated air must travel through the ductwork.
  • Intensity of the light (usually 254 nanometers).

Typically, an airflow rate of 200 cubic feet per minute through the system is recommended. Faster moving air may not receive the necessary light exposure and a slower flow rate means less air is being treated. However, each application is different, depending on the home and the homeowner.

UV units are safe. They do not put any type of pollutant into the atmosphere and will do some good no matter what the situation. However, the units will be more effective if the homeowner maintains a clean HVAC system. Dirty, dusty air vents significantly can diminish the effects of a whole-house system. In addition to improving performance, regular duct cleaning will extend the life of the HVAC system, particularly those using HEPA filters.

Once a UV unit is installed, it is easy to forget. That is why a maintenance schedule should be set up based upon the unit's recommended lamp life so bulbs are replaced on a preventive basis. Typically, a UV bulb is replaced every year, with some manufacturers offering the added value of a two-year bulb.

Dealers should offer basic UV unit maintenance as part of their services. The bulbs are simple to replace but there's a risk of UV light exposure, so this isn't a do-it-yourself task for homeowners. In addition, these are specialty bulbs that aren't available at the local hardware store.

The air purification industry benefits from the same cultural trends that are driving the water treatment industry--the emphasis on healthier living and staying mostly indoors, or "cocooning." When improving the quality of a home's water, treating its air is a natural extension.

In-home air purification still requires a consumer education process, especially when it comes to UV units. The effects of germicidal air purification are invisible. The effects become evident when combined with ozone and HEPA. As people become more educated about the effects of mold, bacteria and viruses in their homes, interest in UV purification is bound to increase.

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