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