Since December 1972 the dustfall has been monitored,
the method used being the standard open - top guage.

In mid 1974, the B.C. Pollution Control Branch provided
Cassiar with four Hi-volume samplers as part of the
Plantsite Emission pre~Permit monitoring requirements.
Samples for suspended particulate and sulphation rate
were obtained at four locations on the process perimeter
between June 18 and September 30, 1974, and forwarded
to the Vancouver laboratory of the Water Resources
Service for analysis. Results of all the Ambient Air
Monitoring to date are provided on Tables 9 to 12.