A new research indicates that sickness among office workers in industrialized countries could be reduced by using ultraviolet lamps to kill germs in ventilation systems.
Ultraviolet germicidal irradiation, or UVGI, is often used in hospital ventilation systems to disinfect the air, but is seldom incorporated in office or other building ducts since there has been no evidence of benefit.
About 70% of workers in North America and Western Europe work indoors and often have unexplained health conditions, such as inflammation of the eyes, throat and nose, as well as respiratory diseases. In a report published this week in The Lancet Medical Journal, Canadian scientists found that the procedure decreased overall worker sickness by about 20%, including a 40% reduction in breathing problems.
According to Dr. Dick Menzies, the study's leader, from the Montreal Chest Institute at McGill University in Montreal, Canada, that the 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. "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 participated in the study. The ultraviolet lamps were designed for cooling coils and drip pans in the ventilation systems of the buildings. The lights were switched on for four weeks, then turned off for 12 weeks. The cycle has been repeated three times for almost a year.
The use of the lights resulted in a 99% reduction of the concentration of germs on irradiated surfaces within the ventilation systems. Some weeks, use of the lamps resulted in a 20% overall reduction in all symptoms for some workers; a 40% reduction in respiratory symptoms and a 30% reduction in mucous problems.
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.
The study may be a landmark in proving that this technique could be cost-effective in commercial office buildings as said by Wladyslaw Jan Kowalski, architectural engineer at the Pennsylvania State University's Indoor Environment Center.
Kowalski, who was not involved in the research, also said that 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 disease specialist at the Imperial College in London, said that disinfecting ventilation systems on their own does not prevent outbreaks of contagious respiratory diseases.