Figure 1: Representation of the experimental apparatus showing the chemical hood, the automatic atomizer (for the dispersion of S. cerevisiae) and the HPV production system. The system is sealed and no hydrogen peroxide vapor is allowed to escape. Petri dishes (in yellow) were placed on the worktop of the hood together with the automatic air sampler (orange), to collect samples of S. cerevisiae. Stainless steel indicators (grey rectangles) inoculated with G. stearothermophilus was placed on the worktop and on the internal walls of the hood.