Noisy work doubles heart disease risk

A persistently noisy workplace more than doubles an employee's risk of serious heart disease, a new study has found.

The findings of the research were published online this week in the journal Occupational and Environmental Medicine. The researchers looked at a representative sample of more than 6,000 US employees, aged from 20 upwards, who had been part of the US National Health and Nutrition Examination Survey (NHANES) between 1999 and 2004. This involved detailed household interviews, to include lifestyle and occupational health, medical examinations, and blood tests.

Participants were grouped into those who for at least three months endured persistent loud noise at work, to the extent that it was difficult to talk at normal volume, and those who did not.

Workers in persistently noisy workplaces were between two to three times as likely to have serious heart problems as their peers in quiet workplaces. This association was particularly strong among workers under 50, who made up more than 4,500 of the total sample. They were between three and four times as likely to have angina or coronary artery disease or to have had a heart attack. The blood tests of these workers did not indicate particularly high levels of cholesterol or inflammatory proteins, both of which are associated with heart disease. But diastolic blood pressure, which measures the pressure of the artery walls when the heart relaxes between heartbeats, was higher than normal, a condition known as isolated diastolic hypertension, or IDH. This is an independent predictor of serious heart problems.

The authors speculate that loud noise day after day may be as strong an external stressor as sudden strong emotion or physical exertion. They conclude: 'This study suggests that excess noise exposure in the workplace is an important occupational health issue and deserves special attention.'

Wen Qi Gan, Hugh W Davies and Paul A Demers. Exposure to occupational noise and cardiovascular disease in the United States: the National Health and Nutrition Examination Survey 1999-2004, Occupational and Environmental Medicine, Online First 5 October 2010; doi 10.1136/oem.055269 [abstract].