Asbestos Certification (ASB) · Lesson 2 of 6

Exposure Assessment and Monitoring: PELs, the Initial Assessment, and the Negative Exposure Assessment

"Exposure Assessment and Monitoring: PELs, the Initial Assessment, and the Negative Exposure Assessment" is lesson 2 of 6 in the Asbestos Certification (ASB) Learning Hub. It opens with "The Two Limits and How They Are Sampled" and works through 5 short steps, then a worked example you can check yourself against.

Open the free trialSee pricing

One-time purchase, no subscription. Law & Business included.

Steps in this lesson

  1. The Two Limits and How They Are Sampled
  2. The Initial Exposure Assessment Comes First
  3. Three Ways to Produce a Negative Exposure Assessment
  4. Daily and Periodic Monitoring
  5. Tell the Workers, and Act on the Numbers

The worked example in the course applies this lesson to a realistic job in 7 steps, from "Classify the work and set the starting presumption" through "Keep monitoring current".

What you'll be able to do

  • Explain the main idea of "Exposure Assessment and Monitoring: PELs, the Initial Assessment, and the Negative Exposure Assessment" in plain language you can use on the exam.
  • Apply this step with confidence: "Three Ways to Produce a Negative Exposure Assessment".
  • Apply this step with confidence: "Daily and Periodic Monitoring".
  • Apply this step with confidence: "Tell the Workers, and Act on the Numbers".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Day 1: TWA Passes, Excursion Fails, Notice Due in 5 Working DaysMONITORING DECISION (CLASS I OR II)Class I work: presume exposure isover the TWA and excursion limitNegative exposure assessment forthe whole job? 1529(f)(2)(C)YESNONo dailymonitoring(f)(3)(A)Monitor everyemployee, daily(f)(3)(A)WORKER A, DAY 1 RESULTS8-hour TWA: 0.07 f/cc (limit 0.1)limit 0.130-min excursion: 1.4 f/cc (limit 1.0)limit 1.0TWA 0.07 is under 0.1: OKExcursion 1.4 is over 1.0: EXCEEDEDResult: protective clothing, respirators,and corrective action in the noticeLab report received Tuesday, March 3: notify workers by Tuesday, March 105 working days: Mar 4, 5, 6, 9, 10 (1529(f)(5)(A))Prior-job data from 14 months ago is outside the 12-month window for a negative assessmentA change in process, equipment, personnel or practice means new monitoring (f)(4)(B)Source: 8 CCR 1529(b), (c), (f)(2)-(f)(5), (i)(1), (n)(1); Cal/OSHA Pocket Guide (Asbestos)CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: The Two Limits and How They Are Sampled

Section 1529(c) sets two permissible exposure limits (PELs): 0.1 fiber per cubic centimeter of air (f/cc) as an eight-hour time-weighted average (TWA), and an excursion limit of 1.0 f/cc averaged over 30 minutes. A fiber is a particle 5 micrometers or longer with a length-to-diameter ratio of at least 3 to 1 (1529(b)). Samples are taken in the worker's breathing zone; full-shift samples represent the TWA, and 30-minute samples taken during the operations most likely to exceed the limit represent the excursion (1529(f)(1)(B)-(C)). Exposure is measured as if the worker wore no respirator (1529(b), "employee exposure").

Step 2: The Initial Exposure Assessment Comes First

Section 1529(f)(2)(A) requires a competent person to perform an exposure assessment immediately before or at the start of the operation, early enough that the control systems and any exposure-triggered requirements are right from day one. Unless a negative exposure assessment exists, the assessment is based on monitoring if feasible, together with all observations, information and calculations, including earlier monitoring (1529(f)(2)(B)). For Class I work, you must presume employees are exposed above both the TWA and the excursion limit until monitoring shows otherwise or you produce a negative exposure assessment.

The remaining 3 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.

More lessons for this trade

Browse all lesson previews

Ready to practice for real?

Try the real classroom free, no sign-up, or get the full course for your trade.

Open the free trialSee pricing

Independent exam preparation. Contractors Classroom is not affiliated with the Contractors State License Board, and no course can guarantee a passing result.