Killing certain bacteria and microbes with ultraviolet (UV) radiaton could be a cost-effective way of reducing employee absence due to the 'sick building'-syndrome. This problem is especially common in buildings with office ventilation systems. Complaints from workers suffering from this are a stuffy nose, itchy eyes and throat and respiratory problems like asthma. Researches have found out that by installing UVGI (Ultraviolet Germicidal Irradiation) lamps in the air conditioning systems they could cut these symptoms by 20%.
The team had UVGI lamps installed in the cooling coils and drip pans of the ventilation systems of three office blocks in Montreal. Resistant bugs sitting on the surfaces were predicted to have a survival time of less than four minutes.
The lamps were switched off for the first 12 weeks of the study, while 771 office workers were quizzed on the specific symptoms they suffered. The lamps were then switched on for four weeks, and off again for 12. In total, three on/off cycles were tested over 48 weeks.
In workers reporting symptoms, switching on the UVGI lamps resulted in a 20 per cent overall reduction. It also slashed respiratory symptoms by 40 per cent, and mucosal symptoms by 30 per cent.
These effects were greatest in people with known allergies and in workers who had never smoked. Muscular complaints were halved in people who never smoked.
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