$5.$ A workplace exposure is measured at $360$ ppm acrylonitrile.

a$.(2$ pt$)$ What is the OSHA $8-$hour PEL for acrylonitrile?

$2$ppm

b$.(4$ pts$)$ What is the protection factor that is needed to protect the worker such that the concentration inside the respirator is reduced to at least the OSHA PEL? $($Show your work$)$

c$.(4$ pts$)$ What is the minimum type of respirator that will provide that kind of protection?