Vibration and Impact Exposures questions for the CHST
CHST Domain 1: Hazard and Risk Identification and Control (K1.23 Common hazards and controls associated with vibration and impact exposures). 1 free questions below. Every answer quotes and links the source document it comes from.
Sources covered
- NIOSH, Criteria for a Recommended Standard: Occupational Exposure to Hand-Arm Vibration (Pub. 89-106) NIOSH Hand-Arm Vibration Criteria Document
Guidance documents are quoted from the published edition linked above; they are recommendations, not regulations.
Question 1
A contractor's safety technician measures vibration from a pneumatic riveting hammer used on steel. Most of the tool's acceleration occurs at frequencies above 400 Hz. The technician plans to report only the ISO frequency-weighted value. What is the main concern with relying on that value alone?
Show answer and source: NIOSH, Criteria for a Recommended Standard: Occupational Exposure to Hand-Arm Vibration (Pub. 89-106)
Answer: A. Most of the high-frequency acceleration would be excluded from the exposure assessment
The NIOSH hand-arm vibration criteria document notes that when ISO frequency weighting is applied to tools with mostly high-frequency acceleration, most of that acceleration drops out of the assessment. The weighted value therefore does not overstate exposure, it is not invalid for pneumatic tools, and it does not equal the unweighted value.
On the job
A safety technician at a ship repair yard tests a pneumatic chipping hammer whose vibration energy sits mostly above 400 Hz. The technician sees that reporting only the ISO frequency-weighted value would drop most of that high-frequency acceleration from the assessment. The weighted figure alone would understate what reaches the operator's hands, so the technician also records the unweighted acceleration before the exposure assessment is finalized.
Study aid, not site-specific safety advice. The official rule controls.
Answer A comes from
NIOSH, Criteria for a Recommended Standard: Occupational Exposure to Hand-Arm Vibration (Pub. 89-106)(opens stacks.cdc.gov in a new tab)“Most of the acceleration occurred at frequencies above 400 Hz (up to 10,000 Hz). If the ISO [1986] frequency-weighting criteria were applied, most of the higher frequency acceleration would be excluded from the exposure assessment.”