The decision this case can inform
Use this record when evaluating dust from fly-ash handling, process leaks, or maintenance work that may create a short, intense exposure unlike routine operation.
NIOSH health-hazard evaluation with personal and area sampling. One extreme sample was explicitly judged nonrepresentative after direct dust-stream impact.
What the public record actually establishes
- F1
Three of seven workers in the initial survey exceeded the then-used 10 mg/m³ total-dust criterion.
- F2
The raw-mill separator area measurements reported 149, 14, and 20 mg/m³ total dust.
- F3
A leak-repair cassette measured 3,800 mg/m³ after direct impact by a dust stream; NIOSH warned that it was not representative.
- F4
Quartz results were below the applicable criteria, while recommendations emphasized shutdown for leak repair, source control, vacuum cleanup, and follow-up sampling.
Facts and reported results are kept separate from the lesson a plant may choose to test.
Operating context
NIOSH evaluated fly-ash handling, process leaks, total dust, respirable dust, silica, and metals.
Intervention or finding
The study linked high local dust to leaks and maintenance and recommended source shutdown/control, leak repair, and engineering/administrative controls.
Documented result
Three of seven initial workers exceeded the then 10 mg/m3 total-dust criteria; quartz results were below applicable criteria.
Plant interpretation
Evaluate the maintenance task itself; repairing a dust leak can create greater exposure than routine operation.
Transfer boundary
One cassette was directly hit by a dust stream and was not representative; the report states this caveat.
Questions to verify at your plant
These are decision checks, not operating instructions. Resolve them through local risk assessment, technical review, and authorization.
- 01
Does the exposure assessment include upset cleanup and leak repair as distinct tasks?
- 02
Can equipment be shut down and depressurized before the leak is approached or opened?
- 03
Are anomalous samples investigated and reported transparently rather than averaged into the dataset?
- 04
Is follow-up sampling scheduled after repairs to verify that the control changed exposure?