Evaluation of Isocyanates Concentration in the Air of the Foam-Producing Section in a Car Manufacturing Company

摘要

Methylene diphenyl diisocyanate (MDI) is the most used isocyanate in the manufacture of polyurethane foam, and it is one of the major causes of occupational asthma. Therefore, in this research, the MDI concentration in the air of the foam-producing section in a car manufacturing company was assessed. To determine MDI concentration, Health and Safety Executive (HSE) air sampling and analysis method, No. 49, was used. In the method, a certain volume of the workplace air was drawn with an impinger content of dimethylformamide and diluted hydrochloric acid. By doing this, organic isocyanates were extracted followed by reactions of hydrolysis to similar amines. The final solution was used for the absorption by the UV-VTS spectrophotometer. Evaluation of MDI in the summer showed that MDI concentration in all parts of the workplace was less than the threshold limit value, and only when local ventilation system and air condition system (air suppliers) were off was the concentration of MDI in the foam injection station higher than the threshold limit value. On the other hand, it is probable that air pollution increases in winter due to closing of doors of the foam-producing section and turning off of the air-conditioning system. Therefore, permanent air-handling and local ventilation is essential when working in the workplace in order to prevent respiratory, skin, eye, and gastrointestinal diseases.