Associations between Long-Term Air Pollutant Exposures and Blood Pressure in Elderly Residents of Taipei City: A Cross-Sectional Study

Abstract

Background: Limited information is available regarding long-term effects of air pollution on blood pressure (BP) and hypertension.

Objective: We studied whether 1-year exposures to particulate matter (PM) and nitrogen oxides (NOx) were correlated with BP and hypertension in the elderly.

Methods: We analyzed cross-sectional data from 27,752 Taipei City residents > 65 years of age who participated in a health examination program in 2009. Land-use regression models were used to estimate participants' 1-year exposures to particulate matter with aerodynamic diameter ≤ 10 μm (PM10), coarse particles (PM2.5-10), fine particles (≤ 2.5 μm; PM2.5), PM2.5 absorbance, NOx, and nitrogen dioxide (NO2). Generalized linear regressions and logistic regressions were used to examine the association between air pollution and BP and hypertension, respectively.

Results: Diastolic BP was associated with 1-year exposures to air pollution, with estimates of 0.73 [95% confidence interval (CI): 0.44, 1.03], 0.46 (95% CI: 0.30, 0.63), 0.62 (95% CI: 0.24, 0.99), 0.34 (95% CI: 0.19, 0.50), and 0.65 (95% CI: 0.44, 0.85) mmHg for PM10 (10 μg/m3), PM2.5-10 (5 μg/m3), PM2.5 absorbance (10-5/m), NOx (20 μg/m3), and NO2 (10 μg/m3), respectively. PM2.5 was not associated with diastolic BP, and none of the air pollutants was associated with systolic BP. Associations of diastolic BP with PM10 and PM2.5 absorbance were stronger among participants with hypertension, diabetes, or a body mass index ≥ 25 kg/m2 than among participants without these conditions. One-year air pollution exposures were not associated with hypertension.

Conclusions: One-year exposures to PM10, PM2.5-10, PM2.5 absorbance, and NOx were associated with higher diastolic BP in elderly residents of Taipei.

Figure 1

Estimates (95% CIs) of diastolic blood pressure in association with an increment of 10 μg/m³ for PM₁₀, 5 μg/m³ for PM_2.5–10, and 10^–5/m for PM_2.5 absorbance stratified by hypertensive (physician-diagnosed hypertension or measured unknown hypertension), diabetic (physician-diagnosed diabetes and use of antidiabetic medication or fasting glucose > 126 mg/dL in health examination), or obese (BMI ≥ 25 kg/m²) status. The estimates were calculated by generalized linear models, adjusted for sex, age, age mean-centered square, smoking status, alcohol consumption, education, traffic proximity, and individual comorbid conditions other than analyzed stratum.