91色情片

Placing ultraviolet lights deep inside ventilation systems might alleviate
鈥渟ick building syndrome鈥� by destroying microbes, say researchers at McGill
University in Montreal. Dick Menzies and his colleagues installed high intensity
UV lights in the ventilation systems on three floors of a office block and
switched them on and off for periods of three weeks each. In Occupational
and Environmental Medicine (vol 56, p 397), the team reveal that the 113
staff鈥攚ho had no way of knowing if the concealed lights were in
use鈥攔eported fewer symptoms and took less sick leave when the UV lights
were on.