Comparison of the removal of macroparticles and MCPs in cleanrooms by surface deposition and mechanical ventilation

The removal of macroparticles (particles ≥5μm) and microbe-carrying particles (MCPs) from cleanroom air occurs by surface deposition or ventilation. In an operational ISO Class 8 cleanroom, small particles ≥0.3μm and ≥0.5μm are mostly removed by air (>99%). The size where half the particles are removed by deposition and half by mechanical ventilation is about ≥10μm, and 90% of particles are removed by deposition when the particle size is ≥40μm. Results were calculated for other ISO cleanroom classifications, and for particles ≥5μm the percentage deposited on surfaces varied from about 11% to 37%. The percentage of MCPs removed by surface deposition in Grade B, C and D cleanrooms that are graded according to the EU Guidelines to Good Manufacturing Practice (2005), varied from 8% to 26%