the cleanroom air. The minimum sample volume
required is calculated based on ISO 14644-1 guidelines as well as sample location based on the new
lookup table released in ISO 14644-1:2015. Airborne
particle counters take a sample of air based on a set
volume programmed into the instrument, and particle counts and sizes are displayed and compared
to the classification tables. ISO 14644-1:2015 states
calibration method of particle counters must follow
ISOI 21501-4 standard.
For an ISO 5 cleanroom classification two particle sizes are required to be reported. Depending
on the cleanroom activity the particle size can be
critically important. In pharmaceutical aseptic processing, 0.5 μm and 5.0 μm are important sizes to
be considered. In a semiconductor wafer processing
cleanroom (ISO 2), there are tighter controls on
cleanliness and therefore 0.1/0.2 μm and/or 0.3/0.5
μm sizes are typically monitored.
For a cleanroom to reach a Grade A or ISO 5
classification, the particle concentrations should be
lower for the two sizes considered for the number of
locations and the sample volume taken.
Airborne particle counters can be set up to generate ISO 14644-1:2015, PICs GMP reports, or even
older ISO 14644-1:1999 or FS209E reports, which
are based on cleanrooms to be classified. The area
to sample and the minimum sample volumes and
locations to sample will provide a pass or fail result
on the reports. The ISO 14644-1:2015 and the PICs
PE 009-13 GMP guide tables for cleanroom classification are shown below.
Using an Air Sampler
For cleanroom classification based on viable particles
an air sampler is used. Selection of an appropriate
air sampler should be based on ISO 14698:2003.
Unlike portable particle counters, air sampler particle capture technology has several options from
using filters, sieves and microscopes, to the most
commonly used impaction technology. Capturing
particles from a sample of air is referred to as active
sampling. Passive sampling is where settled plates are
used to capture particles falling on surfaces. Air sampler collection of particles in impaction technology
uses a media plate with a culture media on the plate.
A set volume is programed into the air sampler and
the particles in the air are pulled through a sample
head where they should impact onto the media.
This media plate is removed, incubated for a cou-
Selecting the right equipment
ple of days and the colonies are counted. The type
or species of the colony are identified using a high
definition electronic microscope. There are several
guidelines on the number of colonies, referred to as
CFU’s colony forming units, allowed based on the
cleanroom classification. The PICs PE 009-13 GMP
Guide table is shown below, with the first two col-
umns applying to air sample using an air sampling
Monitoring instrumentation like airborne particle
counters and active air samplers have varying specifications and models in the market and are supplied
by many different vendors and manufacturers. When
selecting either a particle counter or an air sampler,
keep in mind your specific application and adherence to GMP as the products you manufacture will
require cGMP to be followed. Both instruments
follow ISO and GMP classification tables and other
GMP guidelines for calibration, resolution (d50) and
Verify the instrument you choose is easy to clean, is
small, lightweight has at least a 2-year warranty and can
be serviced on-site to keep downtime to a minimum.
Some questions to consider: how easy will it be to train
my team on using this equipment? Is there a color
touchscreen? Is the firmware intuitive? You should ask
yourself these questions to protect your investment and
plan on this equipment lasting long into the future. Do
your research, talk to multiple vendors, request demos,
do comparisons of each instrument, and even use them
before committing to a purchase.
Jason Kelly is the Director of Systems at Lighthouse
Worldwide Solutions. For the last 20 years, he has worked on
projects for top life science companies assisting in procurement,
delivery and compliance to ensure regulatory acceptance.
for Cleanroom Classification
Setting up an airborne particle counter and isokinetic
sample probe for cleanroom classification.