Health, Safety and Environment - International Labour Organization

Manual 4:HEALTH, SAFETY & ENVIRONMENT FACT SHEETSFact Sheet 16: Noise BackgroundIntensityHazardsOccupationalDeafnessIntensity of sound provides a measure of the amount of energy thatvibrating air particles deliver to the ears. The amount of sound energy canvary enormously. Painful sound is about 10 million-million times asintense as the quietest sound that can be heard. Because a scale of thismagnitude would be impossible to handle, a logarithmic scale is used formeasuring sound intensity, in units called decibels (dB).When noise is measured at work, emphasis is normally given to thefrequencies that have most effect on the human ear. This is done byadjusting the noise meter to take more notice of these frequencies. Thescale used is called the ‘A weighted decibel scale’ or dB(A). Most noisemeters and survey reports will be based on the dB(A) scale.Noise is probably the most widespread and underestimated of industrialhazards. There is a hundred years of knowledge that workplace noise cancause deafness and associated conditions such as tinnitus (ringing in theears). Despite this, millions of agricultural workers are exposed to noiselevels which can cause permanent noise-induced hearing loss. Forexample, noise from: tractors livestock – especially pigs, when they are indoors grain dryers guns machinery tools in a workshop compressors and generatorsThere is a risk of hearing damage from exposures upwards of 80 dB(A). Asa guide, if you cannot hear a normal conversation clearly when you are twometres away from the speaker, the noise level is likely to be around85dB(A) or higher. If you cannot hear someone clearly when you are aboutone metre away, the level is likely to be around 90dB(A) or higher.180 Health, Safety and EnvironmentA Series of Trade Union EducationManuals for Agricultural Workers