'Sick buildings' improve with UV lights

By Rob Stein
The Washington Post

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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 annually, 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. Organisms often thrive in moist, dark ventilation systems. The problem tends to be especially bad in buildings sealed tightly to make them energy efficient.

UV light long has 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 building had separate ventilation systems for the lower and upper halves, allowing researchers to test the approach on four distinct systems.

Researchers sampled the cooling coils for microbes and conducted detailed surveys of the health of 771 workers for a year as UV systems repeatedly were turned on for a month, off for three months and on again for a month.

The UV light killed microbes in the cooling systems, causing a 99 percent reduction in concentrations of bacteria, fungi and endotoxins — irritants produced by mold, the researchers found.

More important, the workers reported a 20 percent reduction in an array of symptoms when the UV lights were on, the researchers reported in a paper to be published in tomorrow's issue of The Lancet, a British medical journal.

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," Menzies said.

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.

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, researchers estimated. But they said that cost easily would be offset by savings from fewer sick days.

Other experts said they were impressed.

"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 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."

Copyright © 2003 The Seattle Times Company