Subjective eye comfort and performance under the different combination of humidity, local air velocity and illuminance

A subjective experiment was conducted using 15 college-aged subjects of both genders in order to evaluate their physiological and psychological reactions, performance and fatigue under the different combinations of indoor humidity, local air velocity and illuminance. The five-hour exposure periods were divided into three sections of 1.5 hours by 10-minute breaks. During each section, subjects performed 3 times of 20-minute task. During the exposure time subjects rated their sensations and visual fatigue, and measured their break up time (BUT) after each task. Local air velocity to subject's face had negative impact on subjective BUT, eye dryness, eye comfort sensation and visual fatigue. Shorter BUT and greater eye dryness sensation was found in low humidity air. Female subjects' BUT was shorter than male. The effects of subjective eye dryness and discomfort rated by females were greater than males. It was because of more contact lens use in female subjects. According to the relationship between BUT and subjective performance, in case that the subjective BUT gets shorter due to indoor environment, subjective performance would become lower.