Whistler had a PM2.5 ‘episode’ during the Saturday night/Sunday morning period this past weekend.  Some elevated hourly concentrations (peaking at 69ug/m3 at 11PM) resulted in a 24 hour rolling average concentration exceeding the BC Ambient Air Quality Objective of 25ug/m3 for 6 hours.  When prolonged, exceedences of the BC AAQO can trigger an air quality advisory, however by Sunday morning, the hourly concentrations had decreased and the 24 hour rolling average was also falling.  It appears that the episode was triggered by a combination of poor dispersion conditions (calm/low wind speed) and, given the timing (evening through early morning hours), woodstove/fireplace emissions.   MOE will be keeping a close watch on the Whistler station for the next couple of days while the current stagnant air mass condition continue in the region.

The episode illustrates the effects of the switch to the new monitoring FEM technology.  See the charts below.

The chart below shows the 24 hour rolling average for the older monitoring technology (PM2.5_TEOM) and the new BAM technology now operating and providing the publicly available PM2.5 data.

image003 300x161 High PM2.5 Episode in Whistler  Jan 18 19






The chart below shows the 1 hour average values for the two monitoring technologies.

image006 300x187 High PM2.5 Episode in Whistler  Jan 18 19







Source: Graham Veale, Air Quality Meteorologist , Ministry of Environment

Want to know more about air quality in BC ?  Check out BC Air Quality – Home