Can I give some general advice for aircrew. HEMS arent grounded yet.
The important thing to remember is that 80% of infection is by aerosol. Treat ALL patients and bystanders as potentially positive. Keep the latter away. Putting a paper mask on the patient is a little help but I put a plastic oxygen mask on ALL patients as it stops most aerosol. No need to connect anything to it!
The real problem is intubation. Intubation can be done safely and is far safer than hand bagging a patient. It needs FFP3 masks and we have reusable plastic half face masks. You don it to intubate, then put it in a paper bag once the airway is isolated and use a normal helmet. Saliva and therefore suction equipment is high risk. Eye protection at all times so aircrew keep helmets on or have spare goggles. If not directly by a patient and not wearing a helmet, an ordinary mask is of no use and possible deleterious. Nitrile gloves and change them every sector.
All surfaces need regular cleaning with disinfectant or disinfectant wipes. Frames on doors get touched, headset connectors, seat controls, switches.
Aircrew are in the front so good ventilation will force air backwards. Remember our very high level helmets merely blow air inside a hood to keep us safe on ITU. Windows and vents fully open. Visors down at all times to deflect aerosol from both patient and medical crew. Dont share helmets or headsets - of course
Paper holds virus for 24 hours - pens are a source of cross infection
Hope this adds some practical advice to the published guidance which is more about direct patient care.