Noise and Blood Pressure: a Cross Sectional and Longitudinal Study of the Effects of Exposure to Loud Noise on Residents in Calabar, Cross River State, Nigeria

Abstract

A cross-sectional and longitudinal study of the effects of loud noise on residents of Calabar, Nigeria, has been carried out using subjective and objective measures. For the cross-sectional study, a 39-item questionnaire was used for the subjective measure. A sample size of 1000 people in the high noise zones with equivalent continuous A-weighted sound pressure levels over 80 dB was randomly selected and used as the study group. In the low noise zone with equivalent continuous A-weighted sound pressure levels under 80 dB, 1000 people were also randomly selected and used as the control group. For the longitudinal study, a sample size of 15 persons who had worked in the Calabar Timber Market from July 2002 (when the first blood pressure assessment was carried out) to July 2006 (when the second blood pressure assessment was carried out) was used. Findings show that exposure to loud noise may not have an immediate effect on blood pressure, but, when individuals are exposed for a long period of time (4 years in this study), it leads to a significant rise in blood pressure.