Noise frequency components and the prevalence of hypertension in workers.

Epidemiological studies have demonstrated a relationship between noise exposure and hypertension, but the association between hypertension and noise frequency components remains unclear. This cross-sectional study investigated the association between noise exposure at different frequencies and the prevalence of hypertension in 188 screw-manufacturing workers. Participants were divided into one high-noise-exposure group (≥80 A-weighted decibel, [dBA]; n=68) and two reference groups, including 68 low-noise-exposure workers (75.8±3.2 dBA) and 52 office workers (61.5±0.5dBA). Personal noise exposure and environmental octave-band analyses were performed at work. Multiple logistic regression models were used to estimate odds ratios (ORs) for hypertension between different noise-exposure categories after adjustment for potential confounders. Male workers exposed to noise levels at high frequencies of 2000, 4000 or 8000Hz had a higher but non-significant risk of hypertension. Those exposed to ≥80dBA for 2-4years, 4-6years and more than 6years had a 4.43-fold (95% CI=1.21-16.15), 1.21-fold (95% CI=0.35-4.21) and 0.95-fold (95% CI=0.16-5.60) risk of hypertension, respectively, compared with reference workers. A significant association was only observed in male workers exposed to ≥70dBA at 4000Hz for 2-4years (adjusted OR=4.22; 95% CI=1.15-15.49) and was not found at other frequencies for any periods. These findings suggest that occupational noise exposure above 80dBA for specific periods may be associated with hypertension, and noise frequency at 4000Hz may have the greatest effect on hypertension.