SafetyCâu 675 / 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
Giải thích
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.
Luyện miễn phí toàn bộ 700 câu hỏi — không cần đăng ký.
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