indicates UV lamps in ventilation systems could reduce worker sickness
EMMA ROSS; AP Medical Writer
LONDON (AP) - 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
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
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
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
"Transport is particularly
important _ buses, subways, trains and airplanes," said Anderson,
who was not connected with study. Disease also spreads through personal
"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: