Describes a dust test used to ascertain the ability of fiber optic components to resist the effects of a dry dust (fine sand) laden atmosphere. This test simulates the effect of sharp edged dust (fine sand) particles, up to 150 mm in size, which may penetrate into cracks, crevices and joints. This test is applicable to all optical devices and to combinations of optical devices and mechanical, electrical, electronic, electrochemical, or electromechanical devices for which exposure to the effects of a dry dust (fine sand) laden atmosphere is anticipated.