This past June my current pulm MD said I would be fine w BE. But then I went to 8000 feet to hike. Took out my pulseoximeter that read 84! And we went back down. I bought an oxygen generator the next day (get an rx for tex purposes) and successfully hiked the following week. We traveled to Peru in 2017 (5 yrs after Big 3 for MAC and BE). My pulm MD at the time gave me a medication used by high altitude hikers (think Mt Everest). I need to find my records. Meanwhile I agree with this post — Machu Picchu should be ok but if you go to Cuzco be prepared! Such a wonderful city to visit!!!!!! We drove over a 14,000 ft pass on our tour. I did ok. Now 8 yrs later I never would have made it. If you are going on a tour see if the directors have oxygen tanks for travelers who get into trouble. Also be sure all your water is boiled or distilled esp if you drink the tea. . We were fortunate to have two doctors on the trip who brought cipro for at least two of us drank tea that gave us tummy troubles.