SafetyQuestion 675 of 700
A worker needs protection where the airborne contaminant is about 8 times the exposure limit. A half-mask air-purifying respirator has an assigned protection factor (APF) of 10. What does that APF tell you?
a.The respirator removes exactly 10 percent of the contaminant
b.A properly fitted half-mask should keep exposure to about one-tenth of the outside concentration, which is adequate here
c.The respirator can be used up to 10 hours before replacement
d.Ten workers can share one respirator per shift
Explanation
Correct: an APF of 10 means a properly selected, fitted, and used half-mask is expected to reduce the wearer's exposure to about one-tenth (10 percent) of the ambient concentration. Since the hazard is about 8 times the limit, reducing to one-tenth brings exposure below the limit, so it is adequate. APF is not a percent removed, a time limit, or a number of users; it is a workplace protection ratio.
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