Nightclub employees could be exposed to dangerously high noise levels, putting them at greater risk for hearing loss, according to a new study.

The study also found that many nightclub managers in Ireland are unaware of noise regulations and do not attempt to protect the health and safety of their employees with hearing tests and noise-awareness training.

For the study, recently published in the International Journal of Noise & Health, a Dublin researcher analyzed the noise exposure of two nightclub employees at each of nine different nightclubs in Ireland. The workers were on average 25 years old and had worked in bars for five years.

A sound-level meter was placed at the bar closest to the dance floor and a dosimeter was attached to the shirt of each participant. The club managers also completed a questionnaire and were interviewed on noise-related health and safety legislation.

The average daily noise exposure of these employees, who worked 20 hours a week on average, was 92 decibels, the study revealed. Between 11:30 p.m. and 1 a.m., the noise levels in the clubs rose by an average of 7 decibels. A 3-decibel increase is akin to doubling the sound pressure level.

Study author Aoife Kelly, a researcher at the Dublin Institute of Technology , said that, over time, noise exposure greater than 85 decibels for eight hours a day can lead to permanent hearing loss.

The nightclub managers had little awareness of noise legislation, according to an institute news release.

Noise risk assessments were made at only two clubs involved in the study. None of the clubs offered their employees hearing tests or trained their staff about the health risks of noise exposure.

Although work safety laws in the European Union require hearing protection be provided to workers exposed to more than 85 decibels, only two clubs provided this protection. Only one actually required its employees to wear it.

Kelly said more people need to be aware of noise exposure regulations, and more club managers need to comply with the legislation.

The study findings are similar to results seen in studies conducted in the United States, Britain and Australia, according to the news release. The researchers said noise-induced hearing loss is the most commonly reported occupational disease in Europe.