Objective

To investigate the relationship between occupational noise exposure and blood pressure.

Methods

We studied 8811 workers at a metallurgical factory, who were exposed to different levels of noise at the worksite: <=80 dB for 8078 workers and >80 dB for 733 workers.

A clinical examination, including measurements of blood pressure (by mercury sphygmomanometer, Korotkoff phases I and V), heart rate (by pulse palpation), body weight and height, was performed.

The subjects were stratified into four age groups (18-30, 31-40, 41-50 and >50 years) and into two body mass index groups: normal weight (<=25 kg/m2) and overweight (>25 kg/m2).

In order to eliminate possible confounding factors and statistical bias, a retrospective case versus control analysis was also carried out.