Even Low Levels of Ambient Air Pollutants Are Associated With Increased Emergency Department Visits for Hypertension

Abstract

BackgroundNumerous 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. MethodsOdds ratios (ORs) for emergency department visits for hypertension in Edmonton, Canada, from April 1992 to March 2002 were associated with pollutant levels (CO, NO2, SO2, O3, and particulate matter [PM] < 10 microns [PM10] and < 2.5 microns [PM2.5] 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. ResultsWe observed associations for all patients and levels of NO2 (IQR = 12.8 parts per billion; OR, 1.06; 95% CI, 1.00-1.12), SO2 (IQR = 2.3 parts per billion; OR, 1.04; 95% CI, 1.00-1.08), and PM10 (IQR = 15.0 μg/m3; OR, 1.06; 95% CI, 1.01-1.11) for lag day 3, as well as for PM10 (IQR = 15.0 μg/m3; OR, 1.06; 95% CI, 1.01-1.11) and PM2.5 (IQR = 6.2 μg/m3; OR, 1.07; 95% CI, 1.01-1.11) for lag day 6. ConclusionsThese findings support the contention that ambient pollution can produce clinically meaningful increases in blood pressure.