Does anyone know how long acclimatization lasts?
I see this is too late for you, but I'll go ahead anyway. This is from the latest (5th edition, 2005) "
Going Higher - Oxygen, Man, and Mountains" by Charles Houston, M.D., et al. This book is, pretty much unarguably,
the source for information on the human body at altitude.
(As an aside, Houston's life is a fascinating one, recently documented in "
Brotherhood of the Rope - The Biography of Charles Houston" by Bernadette McDonald, The Mountaineers Books, 2007. Charlie was one of the recipients of The Belay: Pete Schoening's successful ice ax belay of six falling climbers high on K2 in 1953. There is now a group of people who get together on occasion, called the COB - Children of the Belay. It numbers about 45 people who would never have been born, save The Belay. The book includes a companion DVD, with actual footage of the expedition. I guess I am recommending this book to anyone interested in legends and lore in mountaineering.)
In a section titled "Losing Acclimatization," Houston writes
"There is not much firm data about how long it takes for a person to lose acclimatization once acquired, but most of the changes--even the blood count--revert to normal within a week or two of returning to sea level. It is interesting that shortness of breath on exertion may last for a week at sea level after returning from several weeks at high altitude. This period of 'deacclimatization' has not been studied, but the persistent shortness of breath could be due to an increase in sensitivity of the respiratory center to carbon dioxide. In addition the alkaline reserve (base excess) has been decreased, making the pH of blood more sensitive to small changes in carbon dioxide or to the lactic acid produced by exertion."