Acute effects of night time noise exposure on blood pressure in populations living near airports

Objective: Within the framework of the HYENA project we investigated the effect of short-term changes of noise levels (transportation or indoor noise) on blood pressure (BP) level during nighttime sleep in a field study. Material and Methods: Twenty-four-hour ambulatory BP measurements (ABPM) at 15-minute intervals were carried out on 140 persons living near 4 major European airports taking part in the HYENA project. Noise was measured continuously during the study subjects’ night sleeping period (identified via sleep log) in their bedroom with a noise-meter sampling every 125 milliseconds and recorded on a digital MP3 recorder. Playback on a PC was used subsequently for identification of the source of noise events. Exposure variables included equivalent indoor noise level over 1 and 15 minutes before each BP measurement and presence/absence of event (defined when indoor LAmax >35 dB) before BP measurement. Random effects models were applied with multiple night-time BP values for each participant as outcome. Results: The pooled effects from all 4 centers show that the measured noise 15 and 1 minutes before the systolic and diastolic BP measurement is associated with higher BP in all 4 samples and the association is statistically significant (P < 0.05). Moreover, the presence of an aircraft event, irrespective of its noise level, is associated with a statistically significant increase in diastolic BP. Conclusions: The effects of noise exposure on elevated subsequent BP measurements are clearly shown in our results. More specifically an aircraft noise event is practically associated with elevated BP.