The leader of the Unite union has told ITV News that he wants to see a public inquiry to address concerns about the safety of aeroplane cabin air.
Len McCluskey believes what he calls "aerotoxic syndrome" is a serious health issue and he's concerned that the 20,000 cabin crew his union represents may be exposed to contaminated air during flights.
"Literally all of our cabin crew members will have experienced a 'fume event' at some time. It occurs not regularly, but it occurs sufficiently often for people to be concerned about,” he told ITV News.
"Our intention is to make certain that aerotoxic syndrome doesn’t become a silent killer.”
In most modern aircraft compressed air from the engine is used to supply the cabin during flight. The air, which is hot, provides both a source of oxygen and a means of maintaining a comfortable temperature onboard.
According to the Department of Transport, in normal conditions, the average aircraft cabin is less polluted than the average office, but occasionally leaks happen and oil fumes from the engine can end up in the cabin.
"Fume events", as they are known, are extremely rare but they do happen. ITV News has seen Mandatory Occurence Reports - safety reports - submitted by British-registered airlines to the regulator, the Civil Aviation Authority.
They show that between December 2014 and March of this year, smoke or fumes were reported in the cabin on 167 flights. Some of the cases were serious.
One report in February notes: "Fumes in cabin: eleven of the cabin crew became unwell... oxygen administered, aircraft returned."
On 15 occasions during the four month period, pilots were so concerned by the fumes they made emergency calls to Air Traffic Control. 12 pilots requested priority landings (known as a PAN), 1 flight was diverted and there were 2 "Mayday" calls.
Times pilots were so concerned by fumes they made emergency calls to Air Traffic Control
Pilots requested priority landing
Flight was diverted
In February ITV News revealed that the Senior Coroner for the County of Dorset had written to the Civil Aviation Authority and British Airways to express concern about the quality of cabin air and warned of the "risk that future deaths will occur unless action is taken".
Sheriff Stanhope Payne has been investigating the death of a British Airways pilot, Richard Westgate. Mr Westgate was on medical leave when he died in 2012.
The 43-year-old believed he had been poisoned by repeated exposure to contaminated cabin air. The inquest into his death will open in September.
Of course fume events can affect passengers too.
Mike Booth was on a flight from Bulgaria to Manchester last summer when fumes filled the cabin.
He and the group of 14 other people he was on holiday with believe their health may have been permanently damaged.
They are taking legal action against the airline involved.
Passenger Mike Booth explains:
In an interview in February the chief executive of International Airlines Group, which owns British Airways and Iberia, told ITV News that he believes cabin air is safe.
The Civil Aviation Authority declined our interview request. In a statement the regulator said "passenger and crew safety is of paramount importance to the CAA... several expert studies on the issue of cabin air quality have been carried out in recent years.
The overall conclusion has been that there is no positive evidence of a link between exposure to contaminants in cabin air and possible long-term health effects - although such a link cannot be excluded."
Len McCluskey's point is that the science is, at best, inconclusive and that further research is imperative.
His union has set up a helpline and is encouraging cabin crew to report fume events when they occur.
The union is also offering financial support to the family of Matthew Bass, a Unite cabin crew member who died suddenly last January, aged 35.
As ITV reported in February, a private post-mortem, paid for by the family, concluded he'd had "chronic exposure" to organophosphates - a chemical compound found in jet engine lubricating oil.