Effect of air pollutants on ambulatory blood pressure

Air pollutants have a significant impact on public health. The aim of the study was to find out the relationship between ambulatory blood pressure measured by 24-h ambulatory blood pressure monitoring (ABPM) and the atmospheric pollutants that are measured regularly (PM₁₀, PM_2.5, NO₂ and SO₂). An observational study of temporal and geographic measurements of individual patients (case-time series design) was carried out in Primary Care Centres and Hypertension Units in the Barcelona metropolitan area. We included 2888 hypertensive patients≥18 years old, untreated, with a first valid ABPM performed between 2005 and 2014 and with at least one air pollution station within a radius of <3km.

The mean age was 54.3 (SD 14.6) years. 50.1% were women and 16.9% of the sample were smokers. Mean 24-h blood pressure (BP) was 128.0 (12.7)/77.4 (9.7) mmHg. After adjusting for mean ambient temperature and different risk factors, a significant association was found between ambulatory diastolic BP (DBP) and PM₁₀ concentrations the day before ABPM. For each increase of 10μg/m³ of PM₁₀, an increase of 1.37mmHg 24-h DBP and 1.48mmHg daytime DBP was observed. No relationship was found between PM_2.5, NO₂ and SO₂ and ambulatory BP, nor between any pollutant and clinical BP. The concentration of PM₁₀ the day before the ABPM is significantly associated with an increase in 24-h DBP and daytime DBP.