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Study
Finds UV Works To Treat 'Sick Buildings'
By Rob Stein Ultraviolet lamps
can kill bacteria, mold, fungi and other germs in the ventilation systems of big
office buildings, preventing headaches, coughs, congestion and other symptoms of
"sick building syndrome" among workers, researchers reported
yesterday. The new research
represents the first time that sterilizing air-conditioning systems with UV
light has been clearly demonstrated to help fight sick building syndrome, which
affects millions of workers each year, experts said. "Sick building
syndrome is a composite of many problems. This tackles one component that may be
present in a lot of buildings," said Dick Menzies, an associate professor
of medicine at the Montreal Chest Institute at McGill University in Canada. Sick building
syndrome is a broad term that refers to workplaces in which employees become ill
from exposure to something indoors, such as chemicals used for work; glue and
other substances being emitted by furnishings; and bacteria, mold and other
microbes. The organisms often thrive in moist, dark ventilation systems. The
problem tends to be especially bad in buildings that are sealed tightly to make
them energy efficient. UV light has long been used in hospitals and other settings to kill
microorganisms, and a small pilot study suggested that using it in building
ventilation systems might help fight sick building syndrome. But the new study
represents the first large-scale attempt to test its effectiveness in the real
world. Menzies and his
colleagues installed ultraviolet germicidal irradiation (UVGI) systems -- large
arrays of light bulbs that emit UV light -- in the air-conditioning systems of
three large office buildings in Montreal, irradiating the cooling coils and drip
pans where mold and microbes tend to grow in the water that condenses. One of
the buildings had separate ventilation systems for the lower and upper halves,
allowing the researchers to test the approach on four distinct systems. The researchers
sampled the cooling coils for microbes and conducted detailed surveys of the
health of 771 workers in the buildings for a year as the UV systems were
repeatedly turned on for a month, off for three months and then on again for a
month. The
UV light killed microbes growing in the cooling systems, causing a 99 percent
reduction in the concentrations of bacteria, fungi and endotoxins, which are
irritants produced by mold, the researchers found. More important, the workers reported an overall reduction of 20 percent in
a wide array of symptoms when the UV lights were on,
the researchers reported in a paper to be published in Saturday's issue of
The Lancet, a British medical journal. "There
was a significant reduction in overall symptoms,"
Menzies said in a telephone interview. The
biggest reductions were a 40 percent drop in respiratory complaints and a 30
percent cut in "mucosal" symptoms, which included problems with
workers' eyes, noses and throats. Workers with
allergies, and those who never smoked, seemed to benefit the most. The
lights caused no adverse reactions. "They are perfectly safe. It's as
natural as sunlight. It's not a chemical being sprayed on or something like that
that can cause problems of its own," Menzies said. He stressed that the
approach would not solve all the problems associated with sick buildings, such
as allergic reactions to chemicals. But
based on the findings, the researchers concluded that if UV systems were
installed in most office buildings in North America, work-related health
problems would be avoided in about 4 million workers. "It's not a big
industry at the moment. As far as I'm aware, this is the first big study,"
Menzies said. A UV system would
cost about $52,000 for an office building with 1,000 occupants and would cost
about $14,000 a year to operate, the researchers estimated. But that cost
would easily be offset by the savings from fewer sick days, the researchers
said. "Sick
building syndrome is clearly associated with sickness and absences, and
absenteeism is a huge cost,"
Menzies said. "If
you can prevent one sick day per worker, you've more than paid for the
lights." Other experts said
they were impressed by the carefully designed study and the clear-cut results. "I think the
results provide some pretty powerful evidence about the causal role of
microorganisms in contributing to symptoms in office workers, and points to a
potential reasonable control strategy," said Jonathan Samet, professor and
chairman in the department of epidemiology at the Johns Hopkins Bloomberg School
of Public Health in Baltimore. "It's
a very exciting development," said Edward Nardell, an associate professor
of medicine and public health at the Harvard School of Public Health in Boston. Nardell
said that UV light systems would have other benefits, as well. "If
you put UV in the ducts, you can cut down on anything that's circulating, from
rhinoviruses, which cause the common cold, to influenza and potentially
bioterror agents," Nardell said. "There's a lot to be gained here
aside from this very important sick building problem." ©
2003 The Washington Post Company |