Effect of ultraviolet germicidal lights installed in office ventilation systems on workers' health and wellbeing: double-blind multiple crossover trial

Effect of ultraviolet germicidal lights installed in office ventilation systems on workers' health and wellbeing: double-blind multiple crossover trial

By: Dick Menzies, Julia Popa, James A. Hanley, Thomas Rand, Donald K. Milton
THE LANCET, Vol 362, November 29, 2003

In a double blind, multiple crossover trial of 771 participants in office buildings located in Montreal, Canada. Ultraviolet Germicidal lamps were placed within ventilation systems bathing drip pans and cooling coils with UVC energy. The lamps were off for 12 weeks and then turned on for 4 weeks. This process was repeated three times for 48 consecutive weeks. UVGI resulted in a 99% reduction of microbial and endotoxin concentrations on irradiated surfaces. The conclusion is that the use of UVGI could in the long run prove to be cost-effective compared to the yearly losses from absence because of building-related illness.