I don't think it makes a bit of difference whether the exhaust gasses are created by diesel or gasoline - both are just as deadly. Explosive - only if you do something really stupid, like refueling while it's running. Same as refueling an alcohol stove canister right after you put it out - BOOM!
From my point of view, the Darwin award should go to folks that climb to the top of their mast - I wonder how many people have been killed or injured doing that? I suspect it's a fairly long list as well.
I continually read posts about the danger of a gasoline engine on a sailboat, which drives me nuts. There are thousands upon thousands of gasoline powered sailboats in this country, and in more than 60 years of being on the water, I've never seen one blow up or catch on fire. However, I have witnessed three diesel powered boat fires. All but one burned to the water line. A few months ago, on the TV series Deadliest Catch, one of the crab boats had an injector line blow. The entire engine compartment filled with diesel fumes that were so dense, you could barely see more than 10 feet in the lighted compartment. The engineer, was afraid to press the mic key on the intercom, claiming the tiniest spark could have blown the boat to smithereens. He had to wear a SCUBA rig to work on the problem because the gasses were so deadly. They eventually were able to evacuate the diesel fumes using a huge fan that did not have brushes on the fan motor.
I have had an explosive gas detector on my boat since the day I purchased it. It detects all explosive gasses, including the gasses emitted from charging the boat batteries. It works very, very well, and I tested it using a propane cigarette lighter held about 4 feet away and just pressed the trigger enough so the gas would escape, but not ignite. I held it for about 5 seconds and the alarm went nuts. I had to put a switch in the system so I could turn it off when charging the batteries with the onboard charger - the damned thing would fire off in the middle of the night and wake everyone in the adjacent condos.
I just looked at the study Mainsail talked about, and apparently, the vast majority of those deaths occurred when people fired up gasoline generators in their garages, basements and homes during power outages. Here is an exert from that study: ASHRAE Journal, Sept, 2014, Vol.56(9), p.92(4) [Peer Reviewed Journal]
Description: Concerns exist about the hazard of acute residential carbon monoxide (CO) exposures from portable gasoline-powered generators, which can result in death or serious adverse health effects. As of April 23, 2013 and as shown in Figure 1, the U.S. Consumer Product Safety Commission (CPSC) databases contain records of at least 800 deaths (involving 597 incidents) from CO poisoning caused by consumer use of a generator in the period of 1999 through 2012. (1) Typically, these deaths occur when consumers use a generator in an enclosed or partially enclosed space or, less often, outdoors near a partially open door, window or vent. While avoiding the operation of such generators in or near a home would reduce indoor CO exposures significantly, it may not be realistic to expect such usage to be eliminated completely.
All the best,