Post-Holiday Asthma Exacerbations

I am on Biological Nucala therapy for eosinophilic asthma. I still have a twice daily steroid inhaler but don't usually need my rescue inhaler. Over the past 2 years I've been on 3 fly and cruise holidays. On all cruises, by day 10 I start experiencing symptoms of cold- and flu-like nature. I have used my rescue inhaler, recognising my asthma has become exacerbated. These 14 night cruises have culminated in me been in respiratory distress on the flight home. This has been followed by emergency treatment at the hospital on arriving home. Each time the medics and paramedics have told me it's a common issue and it was suggested that it was the filters on the aircraft. My respiratory constant has prescribed me a course of prednisone steroid tablets and a broad spectrum antibiotic, which I should take immediately if I begin to feel physically ill and as if my asthma is exacerbated. This way they hope to keep me from deteriorating to the point I need hospitalisation. Has anyone else been affected by this vacation issue? If so how did you treat or control your asthma?