BACKGROUND: Numerous studies have reported associations between air pollution and cardiovascular diseases. While several studies illustrate that exposures to air pollutants can elevate blood pressure, few have evaluated the clinical relevance of this relationship. Hence, we aimed to explore the associations between daily concentrations of several air pollutants and emergency department visits for hypertension.
METHODS: Odds ratios (ORs) for emergency department visits for hypertension in Edmonton, Canada, from April 1992 to March 2002 were associated with pollutant levels (CO, NO(2), SO(2), O(3), and particulate matter [PM] < 10 microns [PM(10)] and < 2.5 microns [PM(2.5)] in aerodynamic diameter, respectively) by means of a case-crossover technique with time-stratified strategy to define controls. The analysis was performed for all (N = 5365), male (N = 2069), and female (N = 3296) patients and for six air pollutants lagged by 0 to 9 days. ORs and their 95% confidence intervals (CIs) were reported for an increase in an interquartile range (IQR) for each pollutant.
RESULTS: We observed associations for all patients and levels of NO(2) (IQR = 12.8 parts per billion; OR, 1.06; 95% CI, 1.00-1.12), SO(2) (IQR = 2.3 parts per billion; OR, 1.04; 95% CI, 1.00-1.08), and PM(10) (IQR = 15.0 μg/m(3); OR, 1.06; 95% CI, 1.01-1.11) for lag day 3, as well as for PM(10) (IQR = 15.0 μg/m(3); OR, 1.06; 95% CI, 1.01-1.11) and PM(2.5) (IQR = 6.2 μg/m(3); OR, 1.07; 95% CI, 1.01-1.11) for lag day 6.
CONCLUSIONS: These findings support the contention that ambient pollution can produce clinically meaningful increases in blood pressure.