Methyl methacrylate is a colorless, flammable liquid with an acrid, fruity odor. The primary method of manufacture is based on the reaction of acetone and hydrogen cyanide, and the primary use is in the production of resins or plastics such as Plexiglass and Lucite. Methyl methacrylate vapor is an acute irritant, with eye and mucous membrane irritation occurring at concentrations of 125 ppm. At higher concentrations death will ultimately result from pulmonary edema, although such high concentrations cannot be tolerated voluntarily by man. In the bloodstream, methyl methacrylate has been linked to cardiac arrest and other cardiovascular effects caused by its hypotensive (promoting low blood pressure) properties. No lasting chronic effects have been recorded. The primary emission sources in descending order are production, end product manufacture, and bulk storage. Total emissions are estimated to have been about 7.9 million pounds in 1974. Although emission controls specifically for methyl methacrylate are not reported, two types of controls are used extensively by the chemical industry to control hydrocarbon emissions. These are vapor recovery and incineration. Control by adsorption on activated charcoal is used when recovery is economically desirable. Based on the results of the health effects research presented in this report, and the ambient concentration estimates, it appears that methyl methacrylate as an air pollutant does not pose a threat to the health of the general population. In addition, methyl methacrylate does not appear to pose other environmental insults which would warrant further investigation or restriction of its use at the present time.