Well I know in the underground mining industry, all you can run for an engine is a diesel, for a reason, you can't even have a gas engine running within a hundred feet of the portal! Because of CO gas (carbon monoxide, the silent killer), and I've been around some pretty dirty diesel exhaust's in confined areas under ground for 12 hr shifts, too much diesel particulate probably isn't good for yea, but I never had any problems health wise, I think if you're outside sleeping in you're truck, a little exhaust smell might be annoying, but I highly doubt that it will hurt you any, especially if you're not blowing black smoke, that's just me though