Altitude, life expectancy and mortality from ischaemic heart disease, stroke, COPD and cancers: national population-based analysis of US counties - Ezzati, M; Horwitz, MEM; Thomas, DSK; Friedman, AB; Roach, R; Clark, T; Murray, CJL; Honigman, B (JOURNAL OF EPIDEMIOLOGY AND COMMUNITY HEALTH, 2012)