and disinfectation processes are based on an assumption
that microbial mortality or sporal inactivation follows
known kinetics. The data base of the calculation is
invariably the organism's or spore's survival curves,
which are determined experimentally under conditions
where the lethal agent intensity remains as much as
possible constant. A set of constant temperatures is of
course the most familiar. But sets of ®xed chemical
agent concentrations, radiation doses, high pressure
levels etc., are also used whenever the ecacy of non
thermal processes is to be assessed. The experimental
data are presented in the form of relationships between
the number of surviving organisms, or viable spores,
and the exposure time to the lethal agent. These relation-
ships are frequently expressed in the form of a survival
ratio