MID, if it makes you feel any better breathing these levels of carbon dioxide combined with the methane and ethane gases produced by the fire would result in a very swift death indeed. After reading the report I feel confident that the majority of burns suffered were post mortem. Horrible event all around.
Yes, from all post mortem indicators, unconsciousness was of rapid onset after the first suit failed (the suit loops all interconnected centrally, so the influx of toxic gasses (and there were several) would spread to them all rapidly once one suit was breached (a piece of Grissoms suit was ejected through the CM rupture, which took place 14 seconds after the fire started). Based on the positions the crew were found in, burning was likely not profound at the onset of unconsciousness.
Nonetheless, once the pad crew and rescue personnel could actually see inside the spacecraft (when the hatch was opened, they couldn't see anything in there, even with flashlights because of the black smoke, for many minutes), the impression was...well, let's just say horrifying.
The medical reports mention that some of the burns may have been received antemortem. Although unable to determine to what precise extent, the fact that they emphasised the burns in such a manner seems to imply that the majority were post-mortem. That is of some comfort, I should think.
Nonetheless, it was indeed a horrible event all around. The men basically choked on toxic gasses and black sooty smoke...rapidly, of course, but choked and suffocated.
Enough of this, though. I'll leave people to read the reports, which cover everything in graphic detail.
What is truly irritating is that the uninformed, looking as they do for any thing they can to imply some sort of hoax or mis-conduct by authority, imply that this event, researched, studied, understood and documented to a profound extent as it was, could somehow have been the result of sabotage, and by extension, involved homicide...the homicide of a rookie astronaut and two bonified national heroes.
...at the risk of many other lives, and millions upon millions of dollars of gear...
This is as far over the edge as anything pertaining to Apollo mis-understanding, in my view. I suppose I'm a little touchy about this. I still remember the moment like it happened yesterday.