Correlation between altitude and chronic lower respiratory disease mortality rate. HwangJeongeun JangMiso KimNamkug ChoiSeunghyun OhYeon-Mok Beom SeoJoon 2018 <p>A positive correlation was found and was stronger in counties with higher COPD prevalence (>13%; red dots) than in all counties combined (black circles). COPD, chronic obstructive pulmonary disease.</p>