Jan 30, 2003

Taking the Mystery Out of UV Air Purification

Tech Update

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

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

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

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

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

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

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

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.

About the author