UV lamps in offices may help millions of workers

Significant savings per worker are possible

New research indicates that installing ultra-violet lamps in ventilation systems could significantly reduce sickness among office workers. "Installation of UGVI [ultraviolet germicidal radiation] in most North American offices could resolve work-related symptoms in about 4 million employees, caused by microbial contamination of heating, ventilating, and air-condition systems," claimed the authors of the study that appeared in the Nov. 29, 2003, issue of the British medical journal The Lancet.1

"We have been interested in the office environment and effects on human health for over a decade," relates lead author Richard Menzies, MD, who is with the respiratory epidemiology unit of the Montreal Chest Institute. "We’ve looked at things like varying the outdoor air supply and other factors; and the one thing we identified as important was bacterial mold, and at least one could trace that to the ventilation system. Also, there is a body of evidence that ventilation systems pose a health threat, and that they could harbor mold because of condensation."

Menzies and his teamed combined that knowledge with the fact that UV lights are known to kill almost any organism, and hypothesized that putting such lights in the central ventilation system to shine on the drip pans would reduce symptoms in workers in offices that are fed air by such systems.

Interestingly, while UVGI has often been studied in the past, there had never been a study of its impact on bacteria in office buildings. The research team set out to determine if UVGI irradiation of both the drip pans and cooling coils within office ventilation systems would not only reduce microbial contamination, but also work-related symptoms among employees.

There were 771 participants in the study, which took place in office buildings in Montreal. UVGI was alternatively off for 12 weeks, then on for four weeks. This pattern was repeated three times. The primary outcomes of self-reported work-related symptoms and secondary outcomes of endotoxin and viable microbial concentrations in air and on surfaces were measured six times.

Results are significant

The UVGI reduced overall worker sickness by about 20%, including a 40% drop in breathing problems. The benefits were greatest for workers with allergies and for people who had never smoked. The use of the lights also resulted in a 99% reduction of the concentration of germs on irradiated surfaces within the ventilation systems. "We identified a significant and fairly substantial reduction in symptoms that are possibly related to microbial contamination of the ventilation system — itchy, runny eyes and nose, sore throat, dry throat, as well as respiratory symptoms — chest tightening, coughing and wheezing," notes Menzies, "and we identified that the people most likely to derive benefit were people with a history of allergy — the very groups you would expect to be allergic to mold in the air."

In a large office environment, he continues, there are people who are susceptible to a wide variety of things. "This doesn’t mean, for example, that everyone will react to, say, mold, but the susceptible subgroup will react," he explains. The problem of the sealed office environment and its impact on worker health, Menzies continues, is a multifactorial one. "UVGI may be part of the solution, but it may not be the whole solution," he concedes.

A clear benefit

Nevertheless, Menzies asserts, office workers would clearly benefit from the installation of UVGI lamps in ventilation systems, and the cost of installation would be equaled or exceeded by reduced health care costs. How did Menzies arrive at his estimate of 4 million employees who could be helped by such an initiative? "We found that about 4% overall of all the workers studied, or 10% of the symptomatic workers, got better significantly and consistently," he notes. "If you take 4% of all the workers in the United States who work in office buildings, which is estimated at 100 at million, it shows you that number is conservative, if anything."

It’s a conservative estimate, Menzies continues, because in certain areas, far more than 4% of the workers could be helped. "In the southern United States, for example, which is much more humid, there will be a lot more problems, and therefore the potential benefit of UVGI is a lot greater," he explains.

In terms of cost savings, the estimated $52 for initial installation and $14 a year for operating costs "compare favorably with the estimated yearly losses from absence caused by building-related sickness," the authors wrote. "The costs of sickness easily equal the costs of the system — and that’s just the cost of sickness per absence, never mind the loss of productivity," says Menzies. "NIOSH [National Institute for Occupational Safety and Health] has estimated those costs at between $10 billion and $70 billion in the U.S. — that’s a huge amount of money."

In addition, says Menzies, the use of UVGI can aid in prevention. "It can help prevent illnesses, and certainly will prevent major outbreaks, such as Legionnaires disease and hypersensitivity pneumonitis," he notes.


1. Menzies D, Popa J, Hanley JA, et al. Effect of ultraviolet germicidal lights installed in office ventilation systems on workers’ health and well-being; double-blind crossover trial. Lancet 2003; 362:1,785-1,791.

[For more information, contact:

Richard Menzies, MD, Respiratory Epidemiology Unit, Montreal Chest Institute, Room K1.24, 3650 St. Urbain St., Montreal, PQ, Canada H2 2P4. Telephone: (514) 934-1934. Fax: (514) 843-2083. E-mail: Dick. Menzies@McGill.ca.]