Pulmonary fibrosis and aviation?

[Been Accounting]

A relative is suffering from Pulmonary fibrosis. He has had a long flying career as a pilot, first in the RAF and then in the airline business.

We are trying to identify any possible causes.

I'd be interested to know if anyone has heard of Pulmonary fibrosis being linked to the aviation environment. I'm think of bleed air or similar. I haven't found anything on the web but I thought I would try asking the question of a more specialized population.

Thanks

[Been Accounting]

Since I posted the above question, I have discovered the following document:
https://www.rafmuseum.org.uk/documents/Research/RAF-Historical-Society-Journals/Journal_43_Seminar_Aviation_Medicine.pdf

On p25 it mentions:

Whilst this procedure ensured that aircrew would have an immediate warning of the possibility of hypoxia, the breathing of 100% oxygen gave rise to a high incidence of chest discomfort and coughing following exposure to +Gz accelerations in flight – a condition which became known as ‘Hunter Lung. The Institute conducted laboratory and field studies in the early 1960s which revealed that exposure to +Gz whilst breathing 100% oxygen results in collapse of the lower parts of the lungs. Experiments demonstrated that this lung collapse could be prevented by breathing gas containing 40% nitrogen.

Has anyone come across these symptoms ?

[Radgirl]

High concentrations of oxygen have been known to exacerbate atelectasis where the small airway units in the base of the lungs collapse. Written up several decades ago leading to some anaesthetists only using enough oxygen to prevent hypoxia

I was unaware of any involvement of positive G and struggle to understand its effect

However millions of patients receive very high concentrations of oxygen often for days unecessarily and we dont see fibrosis, only atelectasis. Fibrosis occurs throughout the lungs, not at the bases. Atelectasis resolves in days if you are well leaving no residual injury.

So I think this is a red herring.