July 2018

Composite micrograph at 700X

Regular micrograph at 700X

Proficiency Testing Update

CALA is working closely with Thomas Pang of Ryerson Polytechnic University on a proficiency testing (PT) program for air samples.  Current programs tend to use photos of spores for identification, as it is a challenge to circulate slides prepared from air samples due to slide stability problems.  


However, through the use of new photographic software, 3-D composite photographs of traverses of spore deposit of actual air samples can now be made.  Under a microscope, they simulate the examination of a slide containing spore deposits from an air sample.  This enables us to evaluate many analysts using the same air sample.  


An example of the 3-D composite photograph of the mold deposit on a slide is shown below.

A composite photograph of a traverse of a trace of an air sample can be viewed by opening this link

For the purposes of the Proficiency Testing program, composite photos of approximately 10 traverses of a slide prepared from an air sample will be circulated to the analysts for evaluation during each PT cycle.  Each analyst is required to identify and count the spores according to the ASTM mold method, then report the results of each traverse in a spread sheet.  Prior to circulation, all the spores of the traverses would have been identified, counted and verified by 2 experts.  Their consensus results will be used to evaluate the reported results by the analysts.

To iron out the logistics of the program, there will be several dry runs.  The first dry run began in June and there are more than 20 participants from labs across the United States and Canada.  The next dry run is scheduled for October of this year.  Participation in the dry runs is open and free.  The identities of the participants will be kept confidential.  If you are interested in participating, please contact Thomas Pang by email at thomaswspang@gmail.com.