NIOSH recommends in this document that worker exposure to methylene- chloride (75092) (MC), in the absence of a concurrent carbon- monoxide (630080) (CO) exposures above 9 parts per million (ppm), be limited to 75ppm determined as a time weighted average for up to a 10 hour workday, 40 hour workweek. In the presence of CO levels over 9ppm, the existing CO levels must be figured into the total exposure as the effects of these two toxic agents are additive. Recommendations were given for medical surveillance, labeling of hazardous materials, personal protective equipment and clothing, respirator selection, instruction of employees regarding hazards, safe work practices, rules for confined space entry, monitoring and record keeping requirements. MC has been widely used in industry for paint stripping, manufacture of photographic film, and in aerosol propellants, as a solvent in degreasing, in the diphasic treatment of metal surfaces, in the textile and plastic industries, as the carrier in rapid dry paints, and for extracting heat sensitive edible fats and essential oils. MC has been allowed as a food additive in spice oleoresins and in roasted and instant decaffeinated coffee. Effects resulting from the inhalation of MC vapors include decreased visual performance, auditory vigilance and psychomotor tasks, irregular, severe leg and arm pains, hot flashes, vertigo, stupor, poor night vision, anorexia, precordial pain, rapid pulse, shortness of breath, fatigue, drowsiness, pains in the head, tingling in hands and feet, irritation of the eyes, lung, and respiratory tract, and increased alveolar CO at the end of the work day.