Visibility of protective helmets worn by forestry workers.

Area of Science:

• Occupational Safety and Health
• Vision Science
• Human Factors Engineering

Background:

• High visibility helmets are mandatory for New Zealand forestry workers for protection and to enhance worker visibility.
• Fluorescent yellow-green and pink are the standard helmet colors used, with ongoing debate about their comparative conspicuousness.

Purpose of the Study:

• To determine which helmet color, fluorescent yellow-green or pink, is more visible in a forest environment.
• To assess visibility for workers with normal color vision and specific color vision defects (deutan and protan).

Main Methods:

• Threshold angular sizes of helmet material samples were measured against a realistic forest background.
• Participants included observers with normal color vision, deutan defects, and protan defects (mild defects excluded).

Main Results:

• Yellow-green helmets were significantly more visible than pink for normal and protan observers.
• Pink helmets were significantly more visible for deutan observers.
• Median detection distances varied: normal (yellow-green 500m, pink 400m), protan (yellow-green 500m, pink 185m), deutan (yellow-green 450m, pink 550m).

Conclusions:

• Yellow-green helmets provide superior detection distances for the majority of observers, including those with protan defects.
• The higher reflectance and luminance contrast of yellow-green contribute to its greater visibility.
• Pink helmets may be confused with forest backgrounds by protan observers, significantly reducing detection distances.