The effects of combined exposure to noise and heat on human salivary cortisol and blood pressure

Abstract

Purpose. Noise and heat are the most important physical hazardous agents that can affect physiological parameters. This study investigated the independent and combined effects of noise and heat exposure on human saliva cortisol and blood pressure. Methods. In this experimental study, 72 students were exposed to noise (at sound pressure levels of 45, 75, 85 and 95 dB(A)) and heat (at wet bulb globe temperatures [WBGTs] of 22, 29 and 34 °C) for 30 min. Samples of saliva and blood pressure were taken before and after each independent and combined exposure. Results. The results revealed that the average saliva cortisol and blood pressure in male and female subjects increased significantly after independent exposure to noise at 95 dB(A) and a WBGT of 34 °C. The combined exposure to noise and heat increased saliva cortisol and blood pressure, which was statistically significant for three combinations of 95 dB(A) at 34 °C, 95 dB(A) at 29 °C and 85 dB(A) at 34 °C. Conclusions. Combined exposure to noise and heat could affect saliva cortisol and blood pressure in both male and female groups. Further studies are recommended to capture other combinations of physical hazardous agents, especially in the field.

Keywords:

• noise
• heat stress
• salivary cortisol
• blood pressure
• combined exposure

Acknowledgements

This research was part of a PhD thesis at Shahid Beheshti University of Medical Sciences. The authors wish to acknowledge their financial and technical support. The study proposal was approved by the ethics committee (Ethical code: IR.SBMU.PHNS.1396, 63) prior to its execution.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Shahid Beheshti University of Medical Sciences [Grant Number IR.SBMU.PHNS.1396,63].