Table 2.

Relative effects of selected variables on wood dust exposure levels.

Variable/category	RIE (%) (90% CI)a
Sample duration (minutes)b	77.8 (76.5–79.2)
Sample yearc	96.7 (96.0–97.4)
Intensity ratings of cell
All jobs at low intensity	100 (reference)d
All jobs at medium intensity	125.0 (101.9–198.7)
All jobs at high intensity	235.8 (146.4–407.1)
Sample type
Area	100 (reference)
Personal	171.9 (161.1–183.4)
Province
British Columbia	100 (reference)
Ontario	167.8 (155.0–181.1)

^aRIE and 90% CI.

^bCorresponds to the effect of an increase of 50% in sampling duration. For example, using a reference duration of 60 min (taken as 100%), the exposure level for an increase in duration of 50% (i.e., 90 min) is 77.8% of the reference level (i.e., 22.2% lower).

^cCorresponds to the effect of an increase of 1 year. Using 1989 as a reference year (100%), the relative level for 1990 would be 96.7% of the reference (i.e., 3.3% lower).

^dRIE of the reference level is taken as 100%.