WHOが発表、11億人の若者が難聴のリスクにさらされている
（1.1 billion people at risk of hearing loss WHO highlights serious threat posed by exposure to recreational noise）

27 FEBRUARY 2015 ¦ GENEVA – Some 1.1 billion teenagers and young adults are at risk of hearing loss due to the unsafe use of personal audio devices, including smartphones, and exposure to damaging levels of sound at noisy entertainment venues such as nightclubs, bars and sporting events, according to the World Health Organization. Hearing loss has potentially devastating consequences for physical and mental health, education and employment.

Data from studies in middle- and high-income countries analysed by WHO indicate that among teenagers and young adults aged 12-35 years, nearly 50% are exposed to unsafe levels of sound from the use of personal audio devices and around 40% are exposed to potentially damaging levels of sound at entertainment venues. Unsafe levels of sounds can be, for example, exposure to in excess of 85 decibels (dB) for eight hours or 100 dB for 15 minutes.

“As they go about their daily lives doing what they enjoy, more and more young people are placing themselves at risk of hearing loss,” notes Dr Etienne Krug, World Health Organization (WHO) Director for the Department for Management of Noncommunicable Diseases, Disability, Violence and Injury Prevention. “They should be aware that once you lose your hearing, it won’t come back. Taking simple preventive actions will allow people to continue to enjoy themselves without putting their hearing at risk.”

Safe listening depends on the intensity or loudness of sound, and the duration and frequency of listening. Exposure to loud sounds can result in temporary hearing loss or tinnitus which is a ringing sensation in the ear. When the exposure is particularly loud, regular or prolonged, it can lead to permanent damage of the ear’s sensory cells, resulting in irreversible hearing loss.

WHO recommends that the highest permissible level of noise exposure in the workplace is 85 dB up to a maximum of eight hours per day. Many patrons of nightclubs, bars and sporting events are often exposed to even higher levels of sound, and should therefore considerably reduce the duration of exposure. For example, exposure to noise levels of 100 dB, which is typical in such venues, is safe for no more than 15 minutes.

Teenagers and young people can better protect their hearing by keeping the volume down on personal audio devices, wearing earplugs when visiting noisy venues, and using carefully fitted, and, if possible, noise-cancelling earphones/headphones. They can also limit the time spent engaged in noisy activities by taking short listening breaks and restricting the daily use of personal audio devices to less than one hour. With the help of smartphone apps, they can monitor safe listening levels. In addition they should heed the warning signs of hearing loss and get regular hearing check-ups.

Governments also have a role to play by developing and enforcing strict legislation on recreational noise, and by raising awareness of the risks of hearing loss through public information campaigns. Parents, teachers and physicians can educate young people about safe listening, while managers of entertainment venues can respect the safe noise levels set by their respective venues, use sound limiters, and offer earplugs and “chill out” rooms to patrons. Manufacturers can design personal audio devices with safety features and display information about safe listening on products and packaging.

To mark International Ear Care Day, celebrated each year on March 3rd, WHO is launching the “Make Listening Safe” initiative to draw attention to the dangers of unsafe listening and promote safer practices. In collaboration with partners worldwide, WHO will alert young people and their families about the risks of noise-induced hearing loss and advocate towards governments for greater attention to this issue as part of their broader efforts to prevent hearing loss generally.

Worldwide, 360 million people today have moderate to profound hearing loss due to various causes, such as noise, genetic conditions, complications at birth, certain infectious diseases, chronic ear infections, the use of particular drugs, and ageing. It is estimated that half of all cases of hearing loss are avoidable. To address this issue, WHO collates data and information on hearing loss to demonstrate its prevalence, causes and impact as well as opportunities for prevention and management; assists countries to develop and implement programmes for hearing care that are integrated into the primary health-care system; and provides technical resources for training health workers.

This article reprints it:WHO Press Release