Increased resting heart rate with pollutants in a population based study

Abstract

Background: Air pollution is associated with cardiovascular mortality. Changes in the autonomic nervous system may contribute to cardiac arrhythmias and cardiovascular mortality. This study investigated the relations between air pollutant concentrations of sulphur dioxide (SO₂), ozone (O₃), nitric dioxide (NO₂), and resting heart rate (RHR) in a population based study. Methods: A sample of 863 middle aged men and women, living in Toulouse (MONICA centre) area, was randomly recruited. A cross sectional survey on cardiovascular risk factors was carried. RHR was measured twice in a sitting position after a five minute rest. Multivariate analyses with quintiles of RHR were performed using polytomous logistic regression. Models were adjusted for temperature, season, relative humidity, sex, physical activity, blood pressure, C reactive protein, and cardiovascular drugs. Results: For NO₂, the OR (odds ratio) (95% CI) associated with an increase of 5 μg/m³ in the current day of medical examination was 1.14 (1.03 to 1.25) in quintile Q5 of RHR compared with Q1, p for trend = 0.003. For SO₂, OR was 1.16 (0.94 to 1.44) in Q5 compared with Q1, p for trend = 0.05, and for O₃, OR was 0.96 (0.91 to 1.01) in Q5 compared with Q1, p for trend = 0.11. No significant association was seen when the daily mean concentration of NO₂, SO₂, and O₃ was considered during the previous day as well as when day lag 2 or 3 was considered. The cumulative concentration (three consecutive days) of O₃ is negatively associated with RHR (p for trend = 0.02). Conclusion: Changes in pulse rate could reflect cardiac rhythm changes and may be part of the pathophysiological link between pollution and cardiovascular mortality.