Ultra-Violet Irradiation Could Reduce Office Sickness

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Ultra-Violet Irradiation Could Reduce Office Sickness

January 14, 2004

Sickness among millions of office workers in industrialised countries could be reduced by the use of ultraviolet radiation to kill bacteria and moulds in ventilation systems, conclude authors of a study recently published in The Lancet.

Some 70 percent of employed people in industrialised countries work in air-conditioned offices. These workers frequently have unexplained work-related symptoms such as irritation of the mucous membranes of the eyes, throat, and nose, as well as respiratory symptoms. Dr. Dick Menzies, Director of the Respiratory Epidemiology Unit at the Montreal Chest Institute of McGill University and colleagues assessed whether ultraviolet germicidal irradiation (UVGI) of drip pans and cooling coils within ventilation systems of modern office buildings would reduce microbial contamination, and thus occupants’ work-related illness.

Employees from three office buildings in Montreal participated in the study. UVGI was off for 12 weeks, then on for four weeks for three cycles totalling 48 weeks. 771 workers participated. UVGI had a substantial effect in reducing reported work-related illnesses. In workers with symptoms in some, but not all weeks, UVGI resulted in:

  • A 20 percent overall reduction in all symptoms;
  • a 40 percent reduction in respiratory symptoms; (cough, chest tightness, trouble breathing)
  • a 30 percent  reduction in mucosal symptoms; (irritation/ congestion of nose, eyes, throat)

These benefits were greatest for workers with known allergies and non-smokers

Dr. Menzies who is also Associate Professor of Medicine, Epidemiology, and Biostatistics at the McGill Faculty of Medicine says,  “Installation of UGVI in offices could reduce work-related caused by microbial contamination of heating, ventilation, and air-conditioning systems. In the long run the cost of UVGI installation could prove cost-effective compared with the cost of absenteeism due to building-related illness.”

The study was funded by the Canadian Institute for Health Research (CIHR).



Menzies D, Popa J, Hanley JA, Rand T, Milton DK
Effect of ultraviolet germicidal lights installed in office ventilation systems on workers' health and wellbeing: double-blind multiple crossover trial.
Lancet. 2003 Nov 29;362(9398):1785-91



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