Effects of air pollution on blood pressure and heart rate variability: a panel study of vehicular traffic controllers in the city of São Paulo, Brazil

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Abstract
Aims Evaluating the effects of air pollution on São Paulo city's vehicular traffic controllers by means of risk indicators for cardiovascular diseases. Methods and results Twenty-four hour blood pressure recordings and an electrocardiogram were obtained in 48 healthy, non-smoking vehicular traffic controllers, aged 31–55 years, during three periods: winter 2000, summer 2001, and winter 2001. Effects of air pollutants on the outcomes were estimated using linear regression based on generalized estimated equations, controlling for age, body mass index, humidity, and temperature. An interquartile range (IQR) increase in CO (1.1 p.p.m.) was associated with increases of 2.6 mmHg (95% CI 1.0, 4.2), 1.8 mmHg (95% CI 0.8, 2.8), and 2.4 mmHg (95% CI 1.1, 3.6) in systolic, diastolic, and mean 24 h ambulatory blood pressures. SO2 also had relevant effects on blood pressure. On heart rate variability, an IQR increase of SO2 (9.6 µg/m3) was negatively associated with the standard deviation (SD) of normal RR intervals (SDNN) −7.93 ms (95% CI −15.3, −0.6). Conclusion This study supplies biological plausibility for observational studies on air pollution-related cardiovascular morbidity and mortality.