Researchers from the University of British Columbia examined data on more than 6,000 employed men and women age 20 or older who participated in the National Health and Nutrition Examination Survey between 1999 and 2004. People were questioned about their lifestyle habits and work environments, and were given physical exams.
The study found that those who worked in persistently loud environments for at least three months had two to three times the risk of chest pain, coronary artery disease and heart attack than people who worked in quieter places. At-risk workers didn't have particularly high levels of cholesterol or inflammatory proteins (another risk factor for heart disease) in the blood, but they did show elevated diastolic, or resting, blood pressure.
Loud work places were typically factories, construction sites and other industrial or blue-collar jobs. However, the data showed that the people who worked under such noisy conditions also tended to be overweight and smoke cigarettes, which already puts them at risk for heart disease. The Associated Press reports:
Most of the study participants working in loud workplaces were men aged 40 and were more likely to have other heart risk factors like having a higher than normal body mass index and smoking. After statistically adjusting for those variables, [the study] still found people working in loud places had a higher chance of heart disease.
The authors of the study did not look at the exact relationship between persistently loud noise and heart disease, but theorized that constant noise could lead to a stress response in the body (even noises that register unconsciously during sleep have been shown to raise blood pressure), which is known to contribute to heart risk over the long term.