Well this puts a new perspective on things...
Possibly fatal levels of Carbon Monoxide...
AAIB
Toxicology tests on the blood of the passenger showed a carboxyhaemoglobin (COHb) saturation level of 58%.
COHb is the combination product of carbon monoxide (CO) with haemoglobin, the oxygen-carrying protein molecule contained in red blood cells.
CO is a colourless, odourless gas produced from the incomplete combustion of carbon-containing materials.
It readily combines with haemoglobin in the blood, decreasing the carriage of oxygen and causing a direct effect on the performance of those parts of the body which rely on oxygen for proper function.
A COHb level of 50% or above in an otherwise healthy individual is generally considered to be potentially fatal.
In this type of aircraft, the cockpit is not separated from the cabin2 and it is considered likely that the pilot would also have been affected to some extent by exposure to CO