A system for microbially and/or chemically decontaminating a room such as
a hotel room includes a vapor generator which supplies a decontaminant
vapor, such as hydrogen peroxide vapor to the room. The room is then
aerated to a level at which it is safe for normal occupants to enter. By
using a two step aeration, with a second step at lower humidity than the
first, the concentration of residual hydrogen peroxide is reduced rapidly
to safe levels of 1 ppm or less, typically about 0.5 ppm, in under four
hours. The room is rendered substantially free of contaminants, such as
those responsible for Severe Acute Respiratory Syndrome (SARS), Norwalk
virus, and unpleasant odors.