Exposure to air pollutants and mortality in hypertensive patients according to demography: A 10 year case-crossover study

This study evaluated whether short term exposures to NO₂, O ₃, particulate matter <10 mm in diameter (PM₁₀) were associated with higher risk of mortality. A total of 223,287 hypertensive patients attended public health-care services and newly prescribed at least 1 antihypertensive agent were followed-up for up to 5 years. A time-stratified, bi-directional case-crossover design was adopted. For all-cause mortality, significant positive associations were observed for NO₂ and PM ₁₀ at lag 0-3 days per 10 μg/m³ increase in concentration (excess risks 1.187%-2.501%). Significant positive associations were found for O₃ at lag 1 and 2 days and the excess risks were 1.654% and 1.207%, respectively. We found similarly positive associations between these pollutants and respiratory disease mortality. These results were significant among those aged ≥65 years and in cold seasons only. Older hypertensive patients are susceptible to all-cause and respiratory disease-specific deaths from these air pollutants in cold weather.