Abstract
This survey was made to determine the air concentrations of isocyanate during the application of polyurethane foam to the walls and roof of a mine drift. The application was applied by a spray gun technique to an average foam depth of 1-2 inches with a mix ratio of one part polyol to 1.52 parts MDI at 80°F, the maximal vapor concentration found was 0.056 ppm. The particulates created during the spray operation contained reacting MDI in the spray area and for 60 feet downwind. With adequate respirator protection to filter out the particulate material, the vapor concentration did not cause any obvious irritation to any of the 19 men exposed during this operation.