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

- Exposure to noise, PM2.5 or NOx may be independently associated with elevated blood pressure.
- Noise exposure has transient effects of increased SBP and DBP over 24 h.
- Exposure to PM2.5 has elevated effects on 24-h ambulatory SBP and DBP.
- NOx exposure only relates to elevated ambulatory DBP over 24 h.

Exposure to road traffic noise, fine particulate matter (aerodynamic diameter ≤2.5 μm; PM2.5) and nitrogen oxides (NOx) has been associated with transient changes in blood pressure, but whether an interaction exists remains unclear. This panel study investigated whether noise, PM2.5 and NOx 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 PM2.5 and NOx from five air-quality monitors within 6 km 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 PM2.5 was significantly associated with increased systolic blood pressure (SBP) and diastolic blood pressure (DBP) over 24 h; NOx 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 PM2.5 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 NOx 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.