WorkSafeBC Occupational Hygiene Sampling Guidelines Update

On September 25, 2019 WorkSafeBC revised Guideline G5.53-4 Occupational hygiene methods acceptable to WorkSafeBC. With this revision, the Board has now clearly outlined the expectation for collecting field blanks when conducting occupational hygiene sampling. To break it down, here is the regulation and relevant guidelines.


Section 5.53(4) if the OHS Regulation:

“ Workplace exposure monitoring and assessment must be conducted when using occupational hygiene methods acceptable to the Board”


The board has always had the regulation that mandates that acceptable methods be used to sample. “Acceptable methods” have been defined in the guidelines as methods detailed in standard occupational hygiene references published by the following agencies:

  • OSHA
  • AIHA
  • ASTM International
  • The U.S. EPA

The change that has been made to this guideline is that the Board now explicitly states that the requirement to collect field blanks is necessary for these methods to be considered acceptable. While in the past this was assumed, they are now providing specific guidance surrounding this part of the method. The guidelines now state the following:

  1. Whenever conducting hygiene sampling, you must collect the number of field blanks stated within the acceptable method.
  2. If the method does not state the number of field blanks required, you must collect a minimum of two field blanks for a set of samples.
  3. If sampling will be occurring over the course of several days, each day should be considered a separate set of samples (e.g. if sampling for 2 days in a row, you should collect two field blanks per day for a total of 4 blanks).

Field blanks are used as a way to detect if there was any contamination of the collected samples when setting up the samples or transporting them to the laboratory. The lab analysis will assess the field blank and if any contamination was detected, they can correct the set of samples that was submitted with those field blanks to ensure the results accurately reflect a worker’s exposure.

For more information on occupational hygiene sampling regulations and guidelines, visit the WorkSafeBC website.