Guidong County, Hunan Province
Guidong, a county in Chenzhou on the eastern edge of Hunan, stands at 900 meters. In a province built on river plains and lowland basins, that elevation is the highest any county reaches. Twelve peaks here push above 2,000 meters. Almost five hundred rise past 1,000. The air at that height is thin enough to notice. A visitor arriving from Changsha — four hours south by road — steps out of the car into air that holds 46,000 negative oxygen…