The performance of a ventilation system for controlling airborne styrene exposure in lamination rooms has been evaluated. The system was designed to create a horizontal displacement flow in a tunnellike space.
The effectiveness of the system was evaluated by conventional exposure measurements and with direct reading instruments. The instruments were used for studies of the distribution of styrene as well as with the PIMEX® and GridMap methods. The ventilation system was studied during manual lamination of up to 5-m long boat part molds. The time-weighted average concentrations of styrene ranged from 4.7 to 11 ppm. The results showed that an acceptable level of exposure was attained if work practices were also good. The video films made with the PIMEX method showed that exposure peaks representing only 10 percent of exposure duration accounted for one-third of the exposure. These peaks can be avoided to a certain extent if the worker is aware of them. In this instance, good work practices included working at a position “upstream” from the wet surfaces. Distribution of styrene concentration showed that styrene vapors released from the mold moved straight to the exhaust terminal.The evaluated ventilation system produced a displacement-type air flow pattern, and exposure to styrene was well below the exposure limit during manual lay-up molding.