Study Finds UV
Works To Treat 'Sick Buildings'
By Rob Stein
Washington Post Staff Writer
Friday, November 28, 2003; Page A03
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,
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.
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
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
"There was a
significant reduction in overall symptoms," Menzies said in a
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.
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.
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
"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
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."