Yes, diesel and fuel oil emissions, coming from all uses, not just locomotives, actually do contain small amounts of known carcinogens. And, breathing in large amounts of diesel particulates is associated with developing emphysema. In my career, I've known a thankfully small number of rails who've developed emphysema and lung cancers. But, as you rightly noted, this is completely OT (it's about food mostly, or did you actually read it?) and has nothing whatsoever to do with trains at all. So what's your point exactly?