A discussion warning of the dangers of confined spaces at facilities, factories, or collection systems was presented. A confined space was defined by NIOSH as any space which by design has limited openings for entry and exit, unfavorable natural ventilation which could contain or produce dangerous air contaminants, and which is not intended for continuous employee occupancy. NIOSH investigated 14 confined space incidents, in which 24 fatalities occurred, and found that none of the confined spaces were identified or posted as confined spaces. NIOSH recommendations for warning workers are as follows: employers should identify confined spaces and post easily visible safety signs both in English and in the predominant language of workers who do not read English; entry to the space should be by written permit only; and the signs should use colors and geometric shapes recognized by standards organizations. General guidance for the characteristics and details of the signs was provided. The signs should have an appropriate heading (Danger, Caution, Warning) in appropriate colors. Prohibition signs should be white, with black symbol placed centrally, with a red circular band and cross bar covering at least 35 percent of the area. Any text should be placed on a rectangular supplementary sign, with text in black on a white background, without any graphic symbol.