The effects of exposure to different noise frequency patterns on blood pressure components and hypertension.

OBJECTIVE: Previous studies have indicated a significant association between exposure to noise and blood pressure. However, the effects of exposure to different noise frequency patterns on blood pressure components and hypertension (HTN) have been unknown. METHODS: We recruited a total of 518 eligible workers in this study. According to types of work (office and production-line), overall A-weighted equivalent sound pressure levels (8-h LAeq), and total 8-h LAeq at low (31.5, 63, and 125 Hz), medium (250, 500, and 1000 Hz), and high ( 2, 4, and 8 kHz) frequencies, we classified subjects into four categories, involving office workers (n = 214) exposed to overall 8-h LAeq   90 dB that the difference between the medium and high frequencies was less than 1 dB, and high B noise exposure group (n = 137) exposed to overall 8-h LAeq > 90 dB that the levels of noise at the high frequency were 10 dBA more than the medium frequency. The high A and high B groups were a little difference in total 8-h LAeq at the low and medium frequencies (≤ 3 dBA) and a wide difference at the high frequency (more than 10 dBA). The logistic regression models were applied to determine the odds of HTN among study groups. RESULTS: The significant difference was observed among study groups in the average of systolic blood pressure (SBP), pulse pressure (PP), mean arterial pressure (MAP), and the frequency of HTN (P < 0.05). Also, we found a significant difference in diastolic blood pressure DBP but at the levels of P < 0.10. The odds ratios (ORs) and 95% confidence intervals (CIs) of HTN according to the full adjusted model in the medium, high A, and high B groups compared with the office workers were estimated at 1.66(0.45, 6.10), 2.34(0.80, 6.89), and 4.02(1.63, 9.96), respectively. CONCLUSION: This study indicates noise frequency patterns may play a significant role in the association between noise and blood pressure. More studies are warranted to confirm our findings.