Abstract:
The objective of this study was to determine whether or not exposure to a low level of nitrogen dioxide could cause cardio-respiratory effects in health elderly people. Ten healthy subjects (67-85 years of age) were exposed to clean air and 300 ppb nitrogen dioxide for 30 minutes while at rest. Pulmonary function measurements assessed were forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), FEV 25-75 and peak flow (PEF). Cardiac function measurements assessed were systolic blood pressure, diastolic blood pressure, heart rate, arterial oxygen saturation and heart rate variability (HRV). Exhaled nitric oxide (NO) and carbon monoxide (CO) concentrations were measured as airway inflammation markers. Baseline measurements were conducted before exposure followed by two post exposures, 1hour after (PE1) and 18 hours after (PE2) exposure.
Paired t-tests were used to compare all the health measurements between air and NO2 exposure. Results of this study showed no significant changes in pulmonary function tests attributable to nitrogen dioxide exposure. There was a significant difference (11+10mmHg) between PE1 value and the baseline values of diastolic blood pressure after NO2 exposure compared to air exposure (p<0.04). Systolic blood pressure increased at PE1 compared to baseline (5+9 mmHg) attribute to NO2 exposure although the increase was not significant (p=0.2). No significant changes were seen in other cardiac function measurements. The NO2 exposure did not cause significant changes in either exhaled NO or CO concentrations from breath samples. The result of this study indicates that both systolic blood pressure and diastolic blood pressure are interesting endpoints in studies of air pollution health effects.