Many of today's travelers have medical conditions that may cause problems if they journey to even moderate altitudes. For them, this tightly packed atlas gives elevation, medical facilities, airports, and other information for all US towns, cities, mountains, lakes, and parks more than 4000 feet above sea level, all keyed to detailed maps. The author, born with a heart defect that seriously threatens his life at altitudes that don't affect most of us, spent five years collecting the data. He clearly explains altitude physiology and why medical conditions can cause adverse altitude-related effects. The book is not only invaluable for those with health problems, but is also a handy source of practical information that can be difficult to locate elsewhere.