Aseptic monitoring


In biopharmaceutical industrial manufacturing, the >5 μm particle size (defined as a Macroparticle in ISO 14644-1:2015) is an important size of interest. Viable microorganisms generally aggregate in chains, clusters or pairs (a colony forming units or CFU) greater than 5 μm in size. This measurement is therefore an important early indicator of a contamination problem, and is confirmed in both EU GMP, Annex 1, clause 3; as well as ISO 14644-1:2015:

EU GMP, Annex 1, clause 3 most eloquently states, “The monitoring of the ≥ 5.0 μm particle concentration count takes on a particular significance as it is an important diagnostic tool for early detection of failure. The occasional indication of ≥5.0 μm particle counts may be false counts due to electronic noise, stray light, coincidence, etc. However consecutive or regular counting of low levels is an indicator of a possible contamination event and should be investigated. Such events may indicate early failure of the HVAC system, filling equipment failure or may also be diagnostic of poor practices during machine set-up and routine operation.”

28 If using a portable particle counter, the source implies that 100 LPM should be used with a 10-minute sample (one cubic meter sampling). Frequency of monitoring is made in accordance with the principles of risk management.

In addition to infectious biohazard concerns, all laboratory equipment that creates air movement (instruments that incorporate centrifuges, fans, vacuum pumps, etc.) have internal components that create mechanical friction. When mechanical friction occurs, inert particles are generated and expelled through the exhaust. These particles on new equipment are generally, at a minimum, in the thousands at 0.5 μm and in the tens at 5.0 μm and above. These aerosol sized particles spread widely through production areas.

62 WHO


The latter (>5 μm) particle size is very important as it is a leading indicator of a biocontamination problem as viable organisms usual aggregate in chains clusters or pairs – colony forming units (cfu’s) of >5μm in size.

  • A human hair might typically be about 50 to 80um in diameter
  • A human red blood cell is about 8um.
  • Aspergillus sp. and Penicillium sp. mold spores range from 1um to perhaps 8um typically
  • Many Cladosporium sp. and Stachybotrys sp.mold spores may be 10um to 20um (and range in shape from spherical to oblate to longer particles)
  • Most bacteria are smaller. E. coli is about 2um (viruses are much smaller).

(“u” or “um” here means micron or 1/1,000,000 of a meter or a millionth of a meter or about 1/25,400 ths of an inch if you prefer).