Safety math: rates, dose, slopes and TWA
ASP video lesson, 6:34. ASP Domain 1: Mathematical Calculations
Worked ASP exam math: incidence and DART rates, noise dose and TWA, simple-slope excavation width, and the 8-hour TWA of an air contaminant, each with its source formula.
Watch the first 1:28 free. The full lesson, with captions and the full transcript, is included with every ASP pass. Every rule and number is cited on screen to its primary source.
Transcript of the preview
0:00 Intro
Safety math, for the ASP exam. Every rule and number here is cited to its primary source, on screen.
0:07 Learning objectives
In this lesson, you'll learn to: compute an incidence rate and a serious-case rate, calculate a noise dose and its TWA, size a simple-slope excavation, and find an 8-hour TWA for an air contaminant.
0:24 Incidence rate
Start with incidence rates. The standard formula multiplies cases by 200,000, then divides by employee hours worked. Why 200,000? It equals 100 employees working 40 hours a week, 50 weeks a year.
0:50 Worked example
The same formula gives the rate for the most serious cases: time off, transfer, or restricted duty. Only the case count in the numerator changes. Example: a plant logs 6 recordable cases and 4 serious cases over 250,000 hours. 8. 2. Same base, same hours: only the case count changes.
1:20 Noise math
Always check which count, total or serious, the question asks for. With several noise levels in a shift, the dose is 100 times the sum of each C over its T. C is the actual total time at a level. T is the reference duration for that level from Table G-16a.
Also in the full lesson
- Worked example
- Excavation slopes
- Worked example
- Air contaminants
- Worked example
- On the job
- Common exam traps
- Recap quiz
The full transcript is included with every ASP pass. See passes
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