This document gives direction on the interpretation and application of the results of the measurement
of particle deposition rate on one or more vulnerable surfaces in a cleanroom as part of a contamination
control programme. It provides some instructions on how to influence the particle deposition rate and
reduce the risk of particle contamination on vulnerable surfaces.
This document gives information on how a cleanroom user can use the particle deposition rate
measurements to determine limits that can be set for macroparticles on vulnerable surfaces. It also
gives a risk assessment method by which an acceptable risk of deposition of particles onto vulnerable
surfaces in a cleanroom can be established and, when this is not achieved, methods that can be used to
reduce the particle deposition rate.
An alternative to the particle deposition rate is the particle obscuration rate which determines the rate
of increase of coverage of particles onto an area of surface over time. The particle obscuration rate can
be used in an analogous way to the particle deposition rate and the required particle obscuration rate
for a specified surface can be calculated and the risk from deposited particles reduced.
This document does not:
— provide a method to classify a cleanroom with respect to particle deposition rate or particle
obscuration rate;
— directly consider the deposition of microbe-carrying particles, although they can be treated
as particles;
— give any consideration to surface deposition by contact as, for example, when personnel touch a
product and contamination is transferred.