A British Airways co-pilot who feared contaminated cockpit air was poisoning him died from an unintentional overdose of sedatives, a coroner ruled.
Richard Westgate, of Marlborough, died in 2012 after moving to the Netherlands to seek help for symptoms he thought were caused by "aerotoxic syndrome".
An inquest in Salisbury heard he had been in "excruciating pain".
Coroner Dr Simon Fox recorded a conclusion of accidental death caused by an overdose of pentobarbital.
Contamination not examined
Mr Westgate died in his sleep, in his room at the Bastion Hotel in Bussum, Netherlands, on 11 December 2012, the hearing at Wiltshire and Swindon Coroner's Court was told.
His family said he felt "betrayed" by UK doctors, and the Dutch specialists were the first group of medics who gave him a "light at the end of the tunnel", and he "went there to be cured".
Dr Fox earlier ruled that "exposure to organophosphate in the course of his employment as a commercial pilot" was "not a proper issue to be examined by this inquest".
Speaking after the verdict, Mr Westgate's mother, Judith, said: "Medical experts have said organophosphate cannot be ruled out in causing his condition, so the questions remain.
"We know there are more sick passengers and crew, and we hope today will encourage the millions who fly to ask questions to ensure something is done to make sure others don't suffer like our son."
Mr Westgate's death was originally examined by retired senior coroner for Dorset, Sheriff Payne, who issued a report in February 2015 that raised concerns over air quality in aeroplanes.
The Global Cabin Air Quality Executive says it is common practice for airlines to use warm, compressed air taken directly from aircraft engines to pressurise the cabin.
Its research suggests this air, known as "bleed air", can become contaminated with engine oils and hydraulic fluids, leading to illness among cabin crew through repeated exposure.
However, the air industry has argued there is no threat to passengers or crew.