Health, Safety and Environment - International Labour Organization

Manual 4:HEALTH, SAFETY & ENVIRONMENT FACT SHEETSFor noise that is above 80dB(A) and is continuous, the sound energytransmitted to the hair cells of the inner ear is so great that they adapt byraising their threshold of response, shifting their field of sensitivityupwards and no longer responding to very soft sounds. This phenomenon isknown as temporary threshold shift and its extent depends on the intensityof noise, its duration and to some extent on its frequency composition.Temporary hearing loss is most noticeable when starting on a noisy job.Recovery from temporary hearing loss usually takes a few hours or at most acouple of days if the noise exposure has been severe.People working in conditions noisy enough to induce temporary hearingloss can expect permanent hearing loss to the same degree after about tenyears of exposure to these conditions. Loud continuous noise rarely hurtsthe ear-drum of the little bones of the middle ear; but it damages thesensitive hair cells in the inner ear. This damage is irreversible and thecells cannot be replaced.Noise not only damages hearing sensitivity but can also give rise totinnitus, a disturbing ‘ringing in the ear’, which is actually the echo of ourown hearing mechanism. This usually persists all the time and is especiallytroublesome at night when it can prevent sleep. In people with normalhearing it will get drowned out, but as deafness sets in the echo becomestormenting.The effectsof noiseEven a slight impairment of hearing may result in a significant andirreversible reduction in the quality of life. Hearing loss cuts its victim offfrom other people, social interaction becomes more and more of a strain,and family life becomes difficult.High noise levels also produce stress, which can contribute to circulatoryproblems, digestive problems, psychological disturbances and symptomssuch as nervousness or sleeplessness. InformationHealth andsafety lawAgreementsThere is a wide diversity of approaches in national legislation. Check thesummaries provided by your union educator of applicable laws in yourcountry.Your union may have made agreements with your employer about theprevention of noise hazards. Check if there are any applicable agreements.ILO Convention No. 184 on Safety and Health in AgricultureSee Articles 6 and 7 in Manual 6 for the employer’s duties181 Health, Safety and EnvironmentA Series of Trade Union EducationManuals for Agricultural Workers