This will allow people to work safely in difficult circumstances, such as in {TAIL ~ polluted air} or {HEAD ~ extreme cold}, etc 
This will allow people to work safely in difficult circumstances , such as in { TAIL ~ polluted air } or { HEAD ~ extreme cold } , etc
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH