Any health risks here? scared?

My boyfriend just started a job cleaning oil tanks foe Enbridge. He goes into a big tank with a green suit on and shovels this nasty sludge. When he comes home he smells horrible. The smell is enough to knock you right off your feet. He takes a shower, and uses dawn dish soap and oil remover stuff on his whole body and the smell is still there. This stuff doesn't even get on his skin, just his hands, but the smell is all over his body, even after the shower. My mom insists that the smell will not hurt our baby, because it's just the smell, not the actual sludge crap. Is she right? Is there any chance that this could harm our baby?