The following article is reprinted in its
entirety.
By Emma Ross
Associated Press, London
Posted on Fri, Nov. 28, 2003
LONDON - Sickness among office workers
in industrialized countries could be reduced by using ultraviolet
lamps to kill germs in ventilation systems, new research indicates.
Ultraviolet germicidal irradiation, or UVGI, is sometimes used
in hospital ventilation systems to disinfect the air but is rarely
incorporated into office or other building ducts because there
has been little evidence of a benefit.
About 70 percent of the work force in North America and Western
Europe work indoors, and frequently have unexplained health problems
such as irritation of the eyes, throat and nose, as well as respiratory
illnesses.
In a study published this week in The Lancet medical journal, Canadian
scientists found that the technique reduced overall worker sickness
by about 20 percent, including a 40 percent drop in breathing problems.
"Installation of UVGI in most North American offices could resolve work-related
symptoms in about 4 million employees, caused by (germ) contamination of heating,
ventilation, and air conditioning systems," said the study's
leader, Dr. Dick Menzies from the Montreal Chest Institute at McGill
University in Montreal, Canada.
"The cost of UVGI installation could in the long run prove cost-effective
compared with the yearly losses from absence because of building-related illness," he
added.
A total of 771 employees from three different office buildings
in Montreal were involved with the study.
The ultraviolet lamps were aimed at the cooling coils and drip
pans in the ventilation systems of the buildings. The lights were
turned on for four weeks, then turned off for 12 weeks. The cycle
was repeated three times for almost a year.
The use of the lights resulted in a 99 percent reduction of the
concentration of germs on irradiated surfaces within the ventilation
systems.
Some weeks, use of the lamps resulted in a 20 percent overall reduction
in all symptoms for some workers; a 40 percent reduction in respiratory
symptoms and a 30 percent reduction in mucous problems. The benefits
were greatest for workers with allergies and for people who had
never smoked.
With the lights switched on, the frequency of muscle complaints
among nonsmokers halved and the incidence of work-related breathing
problems among them dropped by 60 percent.
Wladyslaw Jan Kowalski, an architectural engineer at Pennsylvania
State University's Indoor Environment Center, said the study may
be a landmark in proving that the technique could be cost-effective
in commercial office buildings.
Kowalski, who was not involved with the research, also said the
approach could be useful in the broader effort to combat contagious
diseases such as flu, SARS, tuberculosis and cold viruses.
"Theoretically, if a large number of schools, office buildings and residences
were modified, a number of airborne respiratory diseases could be eradicated
by interrupting the transmission cycle," Kowalski said. "Reducing
the transmission rate sufficiently would ... halt epidemics in
their path."
However, Roy Anderson, an infectious diseases expert at Imperial
College in London, said disinfecting ventilation systems by itself
would not stamp out outbreaks of contagious respiratory diseases.
"Transport is particularly important - buses, subways, trains and airplanes," said
Anderson, who was not connected with study. Disease also spreads
through personal contact.
"You've got multiple methods of transmission and for control, you need to
address all of them. It's an interesting new approach worth pursuing, but it
needs detailed investigation," Anderson said.
ON THE NET
The Lancet: http://www.thelancet.com
Pennsylvania State University aerobiological engineering site:
http://www.arche.psu.edu/iec/abe/
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