Yearly Occupation Noise Exposure ≥ 85 Decibels Increases Hypertension Odds by 10%

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A new study presented at the American College of Cardiology (ACC) Asia 2024 found yearly exposure to a power loom increases people’s odds of hypertension by 10%.^1,2 The noise exposure can also increase their blood pressure overall.

“While the mechanism is still not well-explored, it is thought that the stress response by the body to chronic sound exposure causes hormonal imbalances that gradually leads to a permanent elevation of blood pressure,” said Golam Dastageer Prince, MBBS, MPH, medical officer at DGHS Bangladesh and lead investigator, in a press release.²

Prince continued by adding how hypertension impacts more than a billion people worldwide, and only 1 in 5 have it under control. Hypertension is a major cause of premature death.

The new findings only amplify the health risk concerns regarding dangerous noise exposures in the workplace. Noise exposure is considered an occupational hazard in some jobs, leading to hearing loss, physical and psychological stress, and reduced concentration.

Recent studies also showed the harms of noise exposure. Living near noise pollution, such as always hearing highways, trains, and air traffic, can impact cardiovascular health. However, Prince said the current study may not apply to noise experienced during daily life since noise pollution near someone’s home will “typically ebbs and flow.”² Meanwhile, the power loom weavers are exposed to noise in continuous patterns due to the machinery. Thus, the weavers will hear the power looms throughout the day at a constant sound level.

Investigators at the Directorate of General Health Services in Bangladesh studied 289 adult workers in selected weaving factories in the Araihazar sub-district of Narayanganj, Bangladesh, from January to December 2023.

Participants had face-to-face interviews to answer questions about sociodemographics, behavior, dietary habits, and family medical history. Investigators evaluated participants for blood pressure, height, and height. They also measured the noise intensity of the factory.

The sample was mostly male and had a mean age of 34 years. Most of the participants were illiterate and married.

Participants worked at the factories with noise intensity ranging from 96 – 111 decibels (mean: 105.45 dB) for a mean duration of nearly 16 years.¹ The noise exceeds the recommended exposure limits for occupational noise exposures in the United States (85 dB over an 8-hour workday), established by the National Institute for Occupational Safety and Health (NIOSH).

The NIOSH’s dose limit uses a 3-dB time intensity tradeoff, so for every 3-dB increase in noise, the allowed exposure time is cut in half.³ For instance, while for 85 dB it takes 8 hours to reach 100% noise dose, 97 dB takes only 30 minutes to reach 100% noise dose. Although 85 dB is the exposure limit, the NIOSH considers sounds ≤ 70 dB safe.

Despite these workers being exposed to loud noises, none of the power loom weavers wore ear protection.² The noise exposure has impacted workers’ cardiovascular health, as demonstrated by the incidence of hypertension among the sample.

In total, 31.5% of the sample had hypertension, and 53.3% of the participants had prehypertension. Investigators also observed a positive correlation between systolic blood pressure (P < .01) and diastolic blood pressure (P < .01) with noise exposure duration.¹ After adjusting for age, body mass index, and smoking status, the study suggested yearly exposure to loud noise exposure increased the odds of hypertension by 10% (adjusted odds ratio [AOR], 1.1; P < .05).

“As the study focused on workers exposed to more than 85 decibels noise for long periods of time, any profession causing workers to experience similar exposure might experience similar blood pressure impacts,” Prince said.² “We definitely need more exploratory studies to reveal more information about the potential mechanisms and long-term health outcomes.”

References

1. ^{Prince, G and Flora, M, Duration of Workplace Noise Exposure And Blood Pressure Among Rural Adult Weavers. Abstract presented at ACC Asia 2024 from August 16 – 18, 2024 in Delhi, India.}
2. ^{Blood Pressure Levels Impacted by Chronic Occupational Noise Exposure. EurekAlert! August 15, 2024. https://www.eurekalert.org/news-releases/1054076. Accessed August 16, 2024.}
3. ^{Kardous, C, Themann, C, Morata, T. Understanding Noise Exposure Limits: Occupational vs General Environmental Noise. CDC: NIOSH Science Blog. February 8, 2016. https://blogs.cdc.gov/niosh-science-blog/2016/02/08/noise/. Accessed August 16, 2024.}