Sala, and pilot David Ibbotson, crashed on 21 January when travelling to Cardiff from the French city of Nantes.
Tests on the striker’s body found enough evidence of the harmful gas to cause a heart attack, seizure or unconsciousness, an interim report by the Air Accidents Investigation Branch (AAIB) stated.
The cockpit of the Piper Malibu aircraft involved in the crash was not separated from the cabin and it is “likely” that pilot David Ibbotson was also “affected to some extent” by exposure to carbon monoxide, the document added.
The AAIB said the gas can “reduce or inhibit a pilot’s ability to fly an aircraft depending on the level of that exposure”.
Toxicology reports showed Sala’s blood showed a carboxyhaemoglobin (COHb) saturation level of 58%.
COHb is the combination product of carbon monoxide (CO) withhaemoglobin, the oxygen-carrying protein molecule contained in red blood cells.
The report said “It is clear from the symptoms that exposure to CO can reduce or inhibit a pilot’s ability to fly an aircraft depending on the level of that exposure.”
Sala’s family are calling on the AAIB to salvage the wreckage of the plane “without further delay.”
In response, the AAIB said the decision not to recover the aircraft wreckage has been “explained in detail to both families concerned.”