Viruses - Bacteria - Mold - Airborne endotoxins

Ultraviolet light kills germs that cause sick building syndrome, says study

Credit: Canadian Press

Thursday, November 27, 2003

MONTREAL (CP) - Millions of employees in modern office buildings could get relief from work-related illness if ultraviolet lamps were used to kill germs in ventilation systems, new research indicates.

In a study published this week in The Lancet medical journal, McGill University scientists found the technique of shining ultraviolet light on air conditioner cooling coils and drip pans reduced overall sickness by about 20 per cent, including a 40 per cent drop in breathing problems.

Ultraviolet germicidal irradiation, or UVGI, has been used to disinfect the air in hospital operating rooms and ventilation systems as well as meat-packaging plants and the pharmaceutical industry, the study's leader, Dr. Dick Menzies of the Montreal Chest Institute, said Thursday.

"Installation of UVGI in most North American offices could resolve work-related symptoms in about four million employees, caused by (germ) contamination of heating, ventilation and air conditioning systems," Menzies said.

About 60 per cent of workers, including an estimated two million Canadians, spend their days in modern structures with closed ventilation systems, the research indicated.

Sick building syndrome has often been blamed for irritation of the eyes, throat and nose as well as respiratory illnesses such as asthma. Symptoms also include headaches, fatigue and problems concentrating.

The dark and damp insides of air conditioners are good breeding grounds for mould and bacteria. The lights killed these germs after a few minutes, the study found.

"It's a natural sterilizer," Menzies told a news conference.

A total of 771 employees from three different public and private buildings in Montreal were involved in the blind study, starting in 2001.

The lamps were turned on for four weeks, then turned off for 12 weeks. The cycle was repeated three times for a year.

The use of the lights resulted in a 99 per cent reduction in the concentration of bacteria on irradiated surfaces within the ventilation systems. Temperature, humidity and ozone levels were unaffected.

While it had marginal impact on levels of bacteria at work stations, employees noted marked health improvements.

There was a 20 per cent overall reduction in all symptoms, including a 40 per cent reduction in respiratory symptoms and a 30 per cent reduction in mucous problems, the study found.

Non-smokers and those suffering from respiratory problems benefited most. Work-related breathing problems were cut by 60 per cent among non-smokers and the frequency of muscle complaints was halved.

However, Menzies cautioned it's "not a panacea."

"It does not eliminate all symptoms in all people."

Until now, researchers have attempted to tackle the specific bacteria that cause problems. But it is an expensive and onerous task, he said.

The UV lights also could prevent the spread of legionnaires' disease and other airborne diseases.

The cost of installing the units range between $30,000 and $50,000, depending on the size of the building and ventilation system, said Stuart Engel, CEO of Montreal's Sanuvox Technologies which installed the UVGI devices for the study.

The technology has been used in water purification for years but is an emerging market for air quality, he said in an interview.

Sanuvox has sold about 200 of its patented units over several years to Canadian and U.S. building owners. The McGill study results reinforce the company's contention the lights replicate the effect of the sun to destroy mould.

"The (market) potential is excellent because now you've got bioterrorism, you've got many other things out there that people have to look at and have to address," he said.

Wladyslaw Jan Kowalski, an architectural engineer at Pennsylvania State University's Indoor Environment Center, told The Associated Press the study may be a landmark in proving 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," he 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 the 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," he told The Associated Press.

Credit: © The Canadian Press, 2003