Persistent, loud noise in the workplace more than doubles the risk for heart disease, Canadian researchers say. Among those at highest risk are younger men who smoke, which by itself is a risk factor for heart disease, the study authors noted.

"Excess noise exposure in the workplace is an important occupational health issue, especially for younger workers," said lead researcher Dr. Wen Qi Gan, from the School of Environmental Health at the University of British Columbia in Vancouver.

Persistent loud noise does not mean loud music or talking, Gan added, but rather any unwanted sound. In this study, noise was defined as industrial noise, such as noise in mining, lumbering and wood product manufacturing, Gan said.

"Noise control is critical to prevent these noise-related diseases. Whenever possible, protect yourself from exposure to excess noise," he advised.

The report was published in the October 6 online edition of Occupational and Environmental Medicine.

For the study, Gan's group collected data on 6,307 people aged 20 and older who took part in the US National Health and Nutrition Examination Survey between 1999 and 2004.

The participants were asked about their lifestyle and occupational health and other health-related topics, and underwent physical exams and blood tests.

The researchers divided the workers by the type of workplace they had: those who said they put up with persistent loud noise (making it difficult to talk at a normal level) for at least three months, and those whose workplace was relatively quiet. Gan's team found that 21 percent of the individuals said their workplace was noisy almost all the time over a nine-month period. Most of them were men with an average age of 40. Compared with those who worked in a quiet environment, this group tended to be overweight and to smoke, which are risk factors on their own for heart disease.

But even after taking those risk factors and others into account, workers bombarded by a noisy environment were two to three times more likely to have serious heart problems than their counterparts in quiet workplaces, the researchers found.