http://security.blog...-illnesses-grows/
"Early on in the return to fly we had five maintainers that reported hypoxia symptoms," Gen. Daniel Wyman, command surgeon for the Air Combat Command, said during a conference call with reporters Wednesday.

The maintainers are mechanics on the F-22's ground crews who sometimes have to be in the cockpit while the jet's engine is doing a ground run.
If this holds up, this is actually more dangerous then the previous reports. The previous problems could be attributed to problems with the air supply, but this suggests that something is getting into the engine and burning up and it is the residue that is causing the problems.

Jay