Orville Cunningham noticed that people who had heart disease were healthier when living closer to sea level, rather than at high altitudes.
Orville Cunningham, uprofesa we-anesthesia, waphawula ukuthi abantu abanezifo zenhliziyo ezithile baphuthuka kangcono uma behlala eduze kwezinga elwandle kunelabo abahlala ezindaweni eziphakeme.