Blood pressure response to controlled diesel exhaust exposure in human subjects

Exposure to traffic-related air pollution is associated with risk of cardiovascular disease and mortality. We examined whether exposure to diesel exhaust increased blood pressure (BP) in human subjects. We analyzed data from 45 nonsmoking subjects, 18 to 49 years of age in double-blinded, crossover exposure studies, randomized to order. Each subject was exposed to diesel exhaust, maintained at 200 μg/m ³ of fine particulate matter, and filtered air for 120 minutes on days separated by ≥2 weeks. We measured BP pre-exposure, at 30-minute intervals during exposure, and 3, 5, 7, and 24 hours from exposure initiation and analyzed changes from pre-exposure values. Compared with filtered air, systolic BP increased at all of the points measured during and after diesel exhaust exposure; the mean effect peaked between 30 and 60 minutes after exposure initiation (3.8 mm Hg [95% CI:-0.4 to 8.0 mm Hg] and 5.1 mm Hg [95% CI: 0.7-9.5 mm Hg], respectively). Sex and metabolic syndrome did not modify this effect. Combining readings between 30 and 90 minutes, diesel exhaust exposure resulted in a 4.4-mm Hg increase in systolic BP, adjusted for participant characteristics and exposure perception (95% CI: 1.1-7.7 mm Hg; P=0.0009). There was no significant effect on heart rate or diastolic pressure. Diesel exhaust inhalation was associated with a rapid, measurable increase in systolic but not diastolic BP in young nonsmokers, independent of perception of exposure. This controlled trial in humans confirms findings from observational studies. The effect may be important on a population basis given the worldwide prevalence of exposure to traffic-related air pollution.