A sterilisation and disinfection apparatus can include a sterilisation environment for receiving items to be sterilised, a source of hydrogen peroxide and means for feeding to said sterilisation environment a controlled flow of a gaseous dispersion of vaporised hydrogen peroxide, characterised by comprising sensing means the electro-conductivity of which varies in response to a variation of the concentration of vaporised hydrogen peroxide in the gaseous atmosphere to which said sensing means are exposed said sensing means being exposed to said gaseous dispersion and configured to output a signal which is a function of the concentration of vaporised hydrogen peroxide in said gaseous dispersion.
