STSC Respirable Construction Hazards: Silica, Lead, and Asbestos — Questions and Answers
Question 1: What is OSHA's Permissible Exposure Limit (PEL) for respirable crystalline silica in construction under 29 CFR 1926.1153?
- 100 micrograms per cubic meter (μg/m³) as an 8-hour TWA
- 50 micrograms per cubic meter (μg/m³) as an 8-hour TWA (Correct answer)
- 250 micrograms per cubic meter (μg/m³) as an 8-hour TWA
- 10 micrograms per cubic meter (μg/m³) as an 8-hour TWA
Correct answer: 50 micrograms per cubic meter (μg/m³) as an 8-hour TWA
OSHA's 2016 silica rule set the PEL for construction at 50 μg/m³ as an 8-hour TWA — half the previous industry standard. The Action Level, which triggers enhanced monitoring and medical surveillance, is 25 μg/m³. Silicosis is an irreversible, potentially fatal lung disease.
Question 2: A crew is cutting fiber cement siding. Under OSHA's Table 1 of the silica standard (1926.1153), which control is REQUIRED to limit silica exposure during this task?
- Full-face supplied-air respirator at all times during cutting
- Wet cutting methods or use of a saw with an integrated HEPA-filtered vacuum (Correct answer)
- Blood lead level testing before starting work
- Air monitoring performed before each shift
Correct answer: Wet cutting methods or use of a saw with an integrated HEPA-filtered vacuum
OSHA's Table 1 specifies task-specific engineering controls; for cutting fiber cement, wet methods or a vacuum with a HEPA filter are required. An employer who fully complies with Table 1 is deemed to have met the exposure assessment requirements — no separate air monitoring is needed.
Question 3: During an interior renovation, workers discover pipe wrap insulation that may contain asbestos. What is the supervisor's FIRST required action?
- Instruct workers to proceed carefully and avoid disturbing the insulation
- Have workers wear N95 respirators and continue the project
- Stop work in the affected area and arrange for a licensed asbestos inspector to assess the material (Correct answer)
- Notify the project owner and resume work the following day
Correct answer: Stop work in the affected area and arrange for a licensed asbestos inspector to assess the material
OSHA 1926.1101 requires that suspect asbestos-containing material be treated as ACM until tested. Work must stop in the affected area, the area must be restricted, and a licensed inspector must assess and sample the material before any disturbance occurs.
Question 4: Lead exposure on construction sites most commonly occurs during which activity?
- Pouring and finishing concrete foundations
- Torch cutting, grinding, or abrasive blasting of lead-based painted surfaces (Correct answer)
- Operating diesel-powered generators on site
- Installing HVAC ductwork in commercial buildings
Correct answer: Torch cutting, grinding, or abrasive blasting of lead-based painted surfaces
Torch cutting, grinding, and abrasive blasting on surfaces coated with lead-based paint generate fine lead particles and fumes that are easily inhaled or ingested. Lead-based paint is common in structures built before 1978, making renovation and demolition work high-risk activities.
Question 5: Under OSHA's lead standard for construction (1926.62), a worker who is regularly exposed to lead at or above the Action Level must receive medical surveillance that includes:
- Monthly chest X-rays to monitor lung density
- Blood lead level (BLL) monitoring at regular intervals (Correct answer)
- Annual audiometric testing
- Pulmonary function spirometry every six months
Correct answer: Blood lead level (BLL) monitoring at regular intervals
Blood lead level (BLL) monitoring is the primary biomarker for lead absorption. OSHA's construction lead standard requires BLL testing for workers exposed at or above the Action Level of 30 μg/m³, with the frequency of testing increasing as BLL results rise.
Question 6: What is the MINIMUM respiratory protection required for a worker performing tasks that generate respirable silica at or above the Action Level (25 μg/m³) but below the PEL (50 μg/m³)?
- A disposable filtering facepiece (dust mask) rated N95
- A half-face air-purifying respirator with N95 or P100 filters (Correct answer)
- A surgical mask
- No respirator is required below the PEL
Correct answer: A half-face air-purifying respirator with N95 or P100 filters
For silica exposures between the Action Level and PEL, a half-face air-purifying respirator with at least N95 filtration is required. Disposable dust masks are insufficient because they lack a quantified assigned protection factor and do not seal adequately against respirable-size particles.
STSC Respirable Construction Hazards: Silica, Lead, and Asbestos
What is OSHA's Permissible Exposure Limit (PEL) for respirable crystalline silica in construction under 29 CFR 1926.1153?