Short-term exposure to noise, fine particulate matter and nitrogen oxides on ambulatory blood pressure: A repeated-measure study

Exposure to road traffic noise, fine particulate matter (aerodynamic diameter ≤2.5μm; PM_2.5) and nitrogen oxides (NO_x) has been associated with transient changes in blood pressure, but whether an interaction exists remains unclear. This panel study investigated whether noise, PM_2.5 and NO_x exposure were independently associated with changes in 24-h ambulatory blood pressure. We recruited 33 males and 33 females aged 18-32 years as study subjects. Personal noise exposure and ambulatory blood pressure were monitored simultaneously in 2007. During the data collection periods, 24-h data on PM_2.5 and NO_x from five air-quality monitors within 6km of participants' home addresses were used to estimate their individual exposures. Linear mixed-effects regression models were used to estimate single and combined effects on ambulatory blood pressure. Exposure to both noise and PM_2.5 was significantly associated with increased systolic blood pressure (SBP) and diastolic blood pressure (DBP) over 24h; NO_x exposure was only significantly related to elevated DBP. Twenty-four-hour ambulatory blood pressure increased with the current noise exposure of 5 A-weighted decibels (dBA) (SBP 1.44 [95% confidence interval: 1.16, 1.71]mmHg and DBP 1.40 [1.18, 1.61]mmHg) and PM_2.5 exposure of 10-μg/m³ (SBP 0.81 [0.19, 1.43]mmHg and DBP 0.63 [0.17, 1.10]mmHg), as well as the current NO_x exposure of 10-ppb (DBP 0.54 [0.12, 0.97]mmHg) after simultaneous adjustment. These findings suggest that exposure to noise and air pollutants may independently increase ambulatory blood pressure and the risk of cardiovascular diseases.