Transcript Slide 1
بسم هللا الرحمن الرحیم تهیه کننده :دکتر مسعود مطلبی http://healthf.kaums.ac.ir/ [email protected] Examples 90 dB + 90 dB = 93 dB 100 dB + 100 dB = 103 dB Decibel Scales A scale measures what humans hear B scale used by phone company C scale measures all sound Permissible Noise Exposure in Construction Duration/Day (hours) 8.00 6.00 4.00 3.00 2.00 1.50 1.00 .50 .25 or less Sound Level (dBA) 90 92 95 97 100 102 105 110 115 Effects of Noise Exposure Daily Allowable Exposure Times to Noise 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 9 IN IRAN Noise Level Time 85 decibels 88 decibels 94 decibels 97 decibels 100 decibels 115 decibels Allowable Exposure 8 hours 4 hours 1 hour 30 minutes 15 minutes 0 minutes EFFECTS OF NOISE – loss of hearing – Stress – behavioral effects – negative impact on health Effects of Noise Exposure What Exposure to Loud Noise Will Do • Exposure to loud noise will inevitably cause hearing loss over time. • Loud noise damages or destroys the nerves in the inner ear. • Another effect can be “tinnitus” or permanent ringing in the ear. 2 Effects of Noise Exposure Long Term Exposure to Noise • 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. 4 Effects of Noise Exposure Hearing Loss From Noise Exposure • Hearing loss from noise exposure is usually not noticed because it is so gradual. • Usually a person loses the ability to hear higher pitches first. • Often the first noticeable effect is difficulty in hearing speech. 5 Effects of Noise Exposure Tinnitus From Noise Exposure • Exposure to high noise levels can also cause permanent ringing in the ear or “tinnitus”. • Tinnitus sufferers usually complain of constant whistling, squealing, roaring or buzzing in one or both ears. • Severe tinnitus may disrupt sleep, reduce concentration and cause irritability and depression. 6 Effects of Noise Exposure What is Too Much Noise Exposure? • Damage from noise exposure depends on the loudness and length of exposure. • Scientific studies have shown that hearing loss can occur when 8-hour average noise exposure exceeds 85 decibels. 7 Effects of Noise Exposure What is Too Much Noise Exposure? • The risk of hearing loss increases dramatically as noise levels increase. • Exposure to noise levels above 115 decibels for even 5 minutes is very risky. • Impact or banging noise above 140 decibels will cause immediate damage to nerves in the ear. 8 (HLPPS) Hearing Loss Prevention Programs NIOSH(1996)Recommended components of HLPPs : 1-Initial and annual audits of procedure. 2-Assessment of noise exposures. 3-Engineering or administrative control. 4-Audiometric evaluation and monitoring of workers hearing. 5-Use of hearing protectors for exposure equal to greater than 85dBA. 6-Education and motivation of worker. 7-Record keeping. 8-Program evaluation for effectiveness. COMMITMENT BY BOTH MANAGEMENT AND WORKERS IS NECESSARY FOR IMPLEMENTATION OF PROGRAM ARRANGE THE TEAM Audiologist Industrial hygienist Management representative Employee representative Occupational medicine physician Manufacture engineers COMPONENT 1 COMPONENT 2 EXPOSURE ASSESSMENT اهداف اندازه گیری صدا -1تعیین میزان مواجهه کارگران با صدا - 2تعیین میزان صدای ماشین االت -3اندازه گیری محیطی صدا مراحل انجام کار -1تعیین هدف اندازه گیری -2تعیین وسیله اندازه گیری -3کالیبراسون وسیله -4گرد اوری اطالعات الزم -5تعیین استاندارد مواجهه -6بکارگیری روش اجرایی مناسب COMPONENT 3 Engineering control : any modification or replacement of equipment or related physical change at noise source or along the transmission path that reduces the noise level at the employee s ear Administrative controls are defined as changes in the work schedule or operation that reduce worker noise exposures. Noise control engineering: 1- Lower the source noise. 2-Modify the propagation path. 3-Protect receiver. 4-Combination of each. کنترل صدا در منبع: -1انتخاب صحیح دستگاه متناسب با فرآیند تولید. -2نگهداری صحیح دستگاه. -3استقرار مناسب دستگاهها. -4کنترل ارتعاش. -5تغییر در اجزاء وکار دستگاه. -6نصب کاهش دهنده های صدا بر روی دستگاه -7محصور کردن دستگاه کنترل در مسیر انتشار: -1کنترل صدا مبتنی بر جذب صدا. -2کنترل صدا مبتنی بر ایزوالسیون صوتی. -3دفاع صوتی. -4ایجاد پناهگاه صوتی برای کارگر. استراتژی کنترل مبتنی بر جذب: -1اندازه گیری میزان صدا در کارگاه. -2آنالیز صدا در کارگاه در مراکز اکتاو. -3اندازه گیری سطوحی که قابلیت نصب جاذب در آنها وجود دارد. -4تعیین ثابت اتاق در حالت معمولی (قبل از نصب جاذب صدا). -5انتخاب ماده جاذب مناسب با توجه به نتایج آنالیز صدا،قابلیت نصب،هزینه،آسانی نصب،نگهداری و.... -6محاسبه ثابت اتاق بطور تئوریک پس از نصب جاذب(با توجه به مورد3و .)5 -7محاسبه میزان کاهش صدای مورد انتظار بطور تئوریک. -8در نظر گرفتن خطاهای احتمالی. -9برآورد هزینه ها. PATH CONTROLS The second line of attack is controlling noise radiation along its transmission path. ACOUSTIC SHADOW ZONE Source High f requen cy cutoff Lo w fre qu en cy cu t-o ff Acoustic shadow PATH CONTROL S Note advertising space sold on the enclosure. PATH CONTROLS Another option for temporary noise barriers are acoustical curtains. COMPONENT 5 Hearing Protectors Available 85 to 90 dB Shall use 90 dB and higher Shall use if STS Standard Threshold Shift Average 10 db loss at 2,000/3,000/4,000 Hz in either ear This loss triggers hearing conservation actions such as administrative or engineering controls, and/or PPE Hearing Protection Types of Hearing Protection earmuffs earplugs There are three types of hearing protection – ear muffs, earplugs and ear caps. Ear muffs and earplugs provide about equal protection, ear caps somewhat less. 12 ear caps Hearing Protection Ear Plug Comfort Some people may find ear plugs uncomfortable to wear for long periods at first. Ear plugs rarely cause infection or prolonged irritation of the ear canal. Most people can find a comfortable fit by trying several different sizes, types or brands. Custom-molded earplugs can be obtained for maximum comfort. custom molded earplugs 15 Hearing Protection Inserting Foam Earplugs Foam type earplugs are one-size-fits-all and must be inserted properly into the ear. Roll earplug into small cylinder first, then insert in ear. 16 Hearing Protection Inserting Foam Earplugs Earplug incorrectly inserted Earplug correctly inserted 17 Hearing Protection Ear Muffs Ear muffs cover the whole ear and are preferred by some people. They have replaceable pads and some high-tech styles filter out specific noise pitches. They last longer than most plugs. 18 Hearing Protection Attached Earmuffs Some muffs are attached to hardhats or goggles. Some high-tech muffs can filter out certain frequencies or have radios inside for communication in high noise areas. 19 Hearing Protection Ear Muff Comfort & Glasses Muffs can be uncomfortable in hot weather. Muffs don’t seal well for someone with glasses or heavy sideburns. 20 Hearing Protection Ear Caps Ear caps are like earplugs, except they do not go into the ear canal, they only block it. They are good for occasional use or for people who find earplugs uncomfortable. They are not as protective as earplugs or muffs. 21 Hearing Protection Noise Reduction of Hearing Protection The “noise reduction rating” or “NRR” of hearing protection is measured in decibels. The NRR is found on the earmuff or earplug package. The higher the number, the greater the protection. 22 Hearing Protection Ear plugs and muffs are rated with an NRR (Noise Reduction Rating) NRR NRR marked on the package is a measure of how much noise is filtered out Manufacturer's NRR Manufacturers' NRRs are best case OSHA says reduce NRR by 7 decibels Then take 50% off that number Hearing Protection Portable Radios/CD Players “Walkmans” do not provide protection from noise. The earphones are not earmuffs and the music only adds to background other noise. “Walkmans” can exceed 85 decibels alone. 28 COMPONENT 6 Requirements for noise standard Company policy for noise reduction Effects of noise Hazardous noise sources at worksite Training in the use of hearing protectors Audiometry Individual responsibilities for preventing NIHL Management also needs to be educated about elements of HLPP COMPONENT 7 RECORDKEEPING Noise exposure Records Audiometric Records Hearing protection Records Education Records Other Records