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 < 65 dB and production-line workers, including medium noise exposure group (n = 81) exposed to overall 8-h LAeq < 78 dB that difference between the medium and high frequencies was less than 1 dB, high_A noise exposure group (n = 86) encountered 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.