British Columbia’s styrene decision uses separate full-shift and short-term limits

October 7, 2026

WorkSafeBC’s styrene decision established a 10 ppm eight-hour time-weighted average and a 20 ppm short-term exposure limit from January 8, 2025. The decision table lists the two exposure bases separately and records styrene’s removal from the excluded-substances table.

APT’s styrene adoption record links the numerical values to that provincial decision. The Board record identifies the November 2024 approval that preceded implementation.

Two exposure bases need separate assessment

The short-term value addresses a 15-minute period under WorkSafeBC’s exposure-limit framework. A full-shift average can describe a different exposure pattern from a brief task that releases styrene. EHS teams need to identify which exposure basis a result represents before comparing it with the relevant value.

APT’s practical interpretation is to retain task timing beside the full-shift sampling record. Activities such as mixing or handling styrene-containing materials can then be considered when deciding whether a separate short-term assessment is appropriate. This interpretation does not prescribe a universal sampling frequency.

Workplaces governed by another provincial, federal or mining regime require their own governing law and current exposure-limit table. Earlier numerical limits were not verified in this review.

For related developments, consult the industrial hygiene regulatory tracker.