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Noise Measurement and Control CWU – May2, 2011 Eric E. Dickson, CIEC, CIAQC Industrial Hygienist, ESD 101 (509) 789-3518 [email protected] Noise – Irritating to Dangerous 2 Purpose of Noise Measurement Identify overexposed workers and quantify their exposures. Assess noise situation for engineering controls Assess background levels in audiometric test rooms. 3 Effects of Noise Exposure • Our ears can recover from short exposure to loud noise, but over time nerve damage will occur. • The longer and louder the noise, the greater chance permanent damage will occur. • There is really no such thing as “tough ears” or “getting used to it”. 4 Permanent effects of noise Small “hearing hangovers” add up slowly Hearing aids can’t fix hearing loss This is your ear... This is your ear on noise... 5 of 35 Effects of Noise on Humans Hearing loss Dilation of the pupils Secretion of thyroid hormone, adrenaline, adrenaline cortex hormone Heart palpitation Movements of stomach and intestines Muscle reaction Constriction of the blood vessels 6 Allowable Exposure Times The table below shows noise levels and how long a person can be exposed without hearing protection before there is damage to the ear. Noise Level Allowable Exposure Time 85 decibels 8 hours 90 decibels 4 hours 100 decibels 1 hour 105 decibels 30 minutes 110 decibels 15 minutes 115 decibels 0 minutes 7 Types of Noise Loudness Whisper Conversation/3 ft Street sounds Sander Sporting event Motorcycle riding Concerts Shooting range 10 decibels 60 decibels 70 decibels 85 decibels 100 decibels 112 decibels 125 decibels 130 decibels 8 “Rock on”!!! …huh? 9 Portable ear blasters – then and now! 10 DOSH Permissible Exposure Limits WAC 296-817 (DOSH) 8-Hour Time Weighted Average (TWA) 85 dBA Maximum Level (sustained noise of > 1 second in duration) 115 dBA Peak Level (impact/impulse noise of < 1second in duration) 140 dBC 11 Hearing Conservation Program Required if worker 8-hour TWA is higher than 85 dBA Mandatory audiometric testing Make hearing protection available Place warning signs in areas > 115 dBA Record keeping Employee access to records. Engineering and/or Administrative controls required if TWA > 90 dBA 12 Hearing Protection Devices Ear Muffs Ear Plugs (disposable and reusable) Custom-Molded Ear plugs 13 Noise Reduction Rating (NRR) Each hearing protection device has an NRR. Usually range from 20-30dB. Chose appropriate level of protection for the noise exposure. Too little protection won’t block out enough noise Too much can block essential noises such as warning alarms, etc. Correction factor = NRR-7dB 14 Instruments for Measuring Noise Sound Level Meters Measures noise at a given moment Area monitoring – develop a “noise map” May not reflect worker exposure 15 Sound Level Meter settings ‘Slow’ response time ‘A’ scale for continuous monitoring ‘C’ scale to measure impact/impulse noise Range Low: 35-100 dB Hi: 65-130 dB 16 Instruments for Measuring Noise Dosimeters Measure worker exposure for full work shift • Assess compliance w/ noise standard Calculates TWA, LAVG (average for actual sample period), Maximum Levels, and Peak Levels Prints a chart w/ minute-to-minute noise levels 17 Dosimetry Measurements Place dosimeter at top of shoulder Avoid windy days if outdoors Measure all identified noise sources Keep itinerary of tasks and equipment used For retired claimants, chose person whose job most closely matches the claimant Same shift, equipment, routine if possible 18 Dosimeter Settings & Standards WAC 296-817 PEL: 85 dBA TWA Weighting: ‘A’ Exchange (doubling) Rate: 5dB Threshold: 80dB Response: Slow Ceiling: 115dBA (Max), 140 dBC (Peak) 19 Noise Control Three methods – in this order. Engineering Controls Administrative Controls Personal Protective Equipment (PPE) 20 Noise Control – Engineering (1st) Control the source Mufflers, soundproofing, enclosures, fan speed, etc. Control the path Sound absorbing materials on walls or ceilings Barriers (walls, curtains, etc.) Control receiver’s environment Build sound booth, etc. Move farther away from equipment 21 Noise Control – Administrative (2nd) Job rotation Work process change 22 Noise Control – PPE (last resort) If you can’t reduce noise exposure by Engineering or Administrative controls, the last resort is to use Personal Protective Equipment (PPE). PPE should never be the first choice for a permanent solution. Ear muffs, ear plugs, etc. 23 Your hearing is as fragile as an egg shell. It can only be damaged once!! 24