CHST Ergonomics and Musculoskeletal Disorder (MSD) Prevention

Question 1

Which ergonomic risk factor most directly contributes to rotator cuff injuries among construction workers performing overhead tasks?

Accepted Answer

Sustained or repeated shoulder elevation above 60 degrees

Answer

Sustained or repeated work with the shoulder elevated above 60° increases mechanical loading on the rotator cuff tendons and reduces blood flow, leading to tendinopathy and tears. This is a well-documented awkward-posture risk factor specific to overhead construction tasks.

Question 2

The NIOSH Lifting Equation Recommended Weight Limit (RWL) accounts for which combination of lifting variables?

Accepted Answer

Horizontal distance, vertical height, travel distance, asymmetry, frequency, and coupling

Answer

The NIOSH Lifting Equation multipliers include: horizontal distance (H), vertical height (V), vertical travel distance (D), trunk asymmetry angle (A), lifting frequency (F), and hand-to-object coupling (C). These six task variables determine how much the maximum 23 kg ideal load must be reduced.

Question 3

A safety technician observes masons repeatedly bending at the waist to pick up bricks from ground-level pallets. The most effective ergonomic intervention is:

Accepted Answer

Raising the pallet to knuckle height using a pallet jack or adjustable scaffold

Answer

Engineering controls — here, repositioning the work at knuckle height — eliminate the awkward posture at the source. Back belts (PPE) and training (administrative) are lower-order controls that do not change the physical demands of the task. Weight limits without posture correction still allow repetitive bending.

Question 4

Hand-arm vibration syndrome (HAVS) is most associated with prolonged use of which type of construction tool?

Accepted Answer

Chipping hammers and grinders

Answer

HAVS (also called vibration white finger) results from chronic exposure to hand-transmitted vibration typically above 2.5 m/s² A(8). Chipping hammers, grinders, jackhammers, and similar vibratory hand tools are the primary sources in construction. Powder-actuated tools fire too briefly; lifts and benders transmit minimal hand-arm vibration.

Question 5

Which administrative control is most effective for reducing cumulative trauma disorders among workers performing repetitive tasks?

Accepted Answer

Implementing job rotation so no single muscle group is overloaded continuously

Answer

Job rotation distributes repetitive loading across different muscle groups, allowing recovery time and reducing cumulative exposure for any single tissue. Anti-vibration gloves (PPE) have limited effectiveness and don't reduce posture or force demands. Signs and periodic assessments are informational — they don't reduce the physical stress directly.

CHST - Construction Health and Safety Technician Practice Test

CHST - Construction Health and Safety Technician Practice Test

CHST Ergonomics and Musculoskeletal Disorder (MSD) Prevention