Background:
Relatively few studies have explored the relationship between air pollution and cause-specific mortality among hypertensive patients. This study evaluated whether short term exposures to nitrogen dioxide (NO2), ozone (O3), particulate matter <10 mm in diameter (PM10) were associated with higher risk of mortality among a large hypertensive patients.
Methods:
A total of 223,287 hypertensive patients who attended any public health-care services in Hong Kong and prescribed at least 1 antihypertensive agent for the first time between 2001 and 2005 were followed up until 2010. A time-stratified, bi-directional case-crossover design was adopted to study the association between environmental exposures and mortality outcomes.
Results:
For all-cause mortality, significant positive associations were observed for NO2 and PM10 at lag 0 to 3 days per 10 MIUg/m3 increase in concentration and the excess risks ranged from 1.187%- 2.501%. Significant positive associations were found for O3 at lag 1 and 2 days and the excess risks were 1.654% (95% C.I. 0.469%, 2.852%) and 1.207% (95% C.I. 0.025%, 2.404%), respectively. We found similarly positive associations between NO2 (excess risks: 1.786%-2.798%), PM10 (1.126%-1.847%), O3 (3.035%-3.355%) and mortality due to respiratory disease. In stratified analysis, these significant results were observed amongst those aged >65 years and in cold seasons only.
Conclusions:
Older hypertensive patients are susceptible to all-cause and respiratory disease-specific deaths from these air pollutants in cold weather. This implies urgent need for protective air pollution standards for this susceptible population.
Temperature Inversions, Meteorological Variables and Air Pollutants and Their Influence on Acute Respiratory Disease in the Guadalajara Metropolitan Zone, Jalisco, Mexico
