Presentation on theme: "Noise in Road Construction Developed by the Division of Occupational Safety and Health (DOSH) August, 2009."— Presentation transcript:
Noise in Road Construction Developed by the Division of Occupational Safety and Health (DOSH) August, 2009
What this presentation covers Hearing loss rates and claims facts Noise levels of construction equipment Control methods to reduce harmful noise exposures Resources
Hearing loss is expensive! Hearing loss is 1/3 of all costs of permanent impairments. Hearing loss is the most expensive occupational disease for road construction workers. Incidence rate is 10 times higher for Road Construction risk class than for all other risk classes. Hearing loss claims rate is highest of all construction risk classes. In Washington State, The result is higher industrial insurance premiums paid by road construction contractors.
Noise and hearing loss 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 Noise level (dBA) Noise is measured in units called decibels (dBA). For more information on noise and hearing, see DOSH webpage: Noise Exposure – Hearing LossNoise Exposure – Hearing Loss Scientific studies have shown that hearing loss can occur when 8-hour average noise exposure exceeds 85 decibels. Threshold of pain Freeway noise City traffic Normal conversation (3) Urban residence Threshold of hearing Construction noise levels are often above 85 dBA (A-weighting is a standard of sound measurement used to evaluate continuous noise levels; designated as dBA) Bulldozer Jackhammer Chipping hammer Soft whisper (5) Jet take-off (200)
Some Common Noise Levels in Construction Source: Center to Protect Workers Rights Decibels (dBA) 60 70 80 85 90 100 110 120 Jackhammer Concrete joint cutter Skilsaw Bulldozer Earth Tamper Crane Hammer Gradeall Front end loader Backhoe 110-113 102-111 99-102 88-102 93-96 90-96 87-95 87-94 86-94 84-93 Pneumatic chipping hammer
Noise Sources in Road Work Type and condition of equipment being operated Other equipment running at the same time Enclosed or partially enclosed spaces (e.g., underpass) Traffic around work site Several factors influence the noise levels to which workers are exposed: Underpass Underpass work
When is hearing protection required? At noise exposures of 85 dBA TWA 8 * and higher, you must use a hearing protection device. Wherever the noise exposure is 90 dBA TWA 8 and higher, feasible controls must be used to reduce your exposure. *Time-weighted average during an 8-hour period High Noise Exposures Rules of Thumb You need protection: If you have to shout at someone 3 feet away to be heard When using electric, gasoline, or air powered tools When sitting in an open cab of dozers, rollers, some cranes, earth moving or road building equipment
What are some methods to control noise exposures? Substitute quieter process or equipment Eliminate or minimize at the source Isolate/enclose the process or operator Increase distance from the source Change work practices Implement a hearing conservation program The most desirable methods of controlling a noise problem are to use quieter process/equipment, eliminate the noise at the source, or to block the noise from reaching you. Using hearing protection devices (ear plugs, muffs) isn't considered a control of the noise hazard. There are many drawbacks and using them will not always be effective.
Noise control methods Substitute quieter process or equipment: Replacing a large jackhammer with a middle range one reduced the noise level by 10 dBA. New quieter generators have sound- proofing and produce only 75 dBA at 1 meter and 65 dBA at 7 meters under load.
Noise control methods –Install silencers/mufflers –Retrofit old equipment –Operate equipment as designed per manufacturers instructions –Damp noisy equipment and parts install sound-absorbing material or vibration isolation systems –Maintain equipment properly replace worn, loose, or unbalanced machine parts that cause vibration keep machine parts well lubricated to reduce friction adjust belts and valves, tighten bolts Eliminate or minimize noise at the source: Acoustically treated operator cabins on earth-moving equipment have noise levels of 75 dBA or below.
Noise control measures –Noise enclosures –Noise barriers must be higher and wider than noise source to work effectively may be simple walls or curtains of acoustic materials ½-inch plywood can provide a 10dB noise reduction place close to noise source –Include acoustic panels or baffles to walls/ceilings –Minimize leaks and openings e.g., cover joints with 1/8-inch thick neoprene strip or duct tape Isolate/enclose the process or operator: A portable screen set up around a power pack reduced the noise level from 98 to 90 dBA at 1 meter.
Noise control measures Isolating or enclosing noisy equipment with operator- a caveat: This method will reduce noise levels outside the barrier, but may increase noise levels inside the barrier. if the source of noise is equipment operated by a worker, his or her noise exposure may be increased because of reflected noise. Lining the barrier with sound absorbing material will reduce the reflected noise to operator. Reflected Noise Noise from source BARRIER Transmitted Noise
Noise Control measures –Keep noisy equipment away from walls or other surfaces that will reflect noise toward you. –Combine distancing and barriers to further reduce noise exposure. Using both methods results in greater noise reduction than would be achieved from either method alone. Increase the distance between the noise source and you: –Every doubling of the distance between you and the noise source results in as much as a 6 dB decrease in noise level – thats a four-fold reduction! -This is true if there is no reflected noise. The reduction will be less if there are walls or partitions between you and the noise source.
Other Noise Control Measures Change employee work practices: –limit time exposed: job rotation, rescheduling work –limit use of noisy equipment –provide breaks away from the noisy area –turn off equipment not in use
Hearing Conservation Program When noise levels cant be controlled through other means, you must implement a hearing conservation program which consist of the following: –Provide baseline and annual audiometric testing –Measure noise exposure levels –Provide hearing protection –Do employee training and education –Maintain employee exposure and hearing loss records Chapter 296-817 WAC Details of requirements:
Summary Substitute quieter process or equipment Eliminate or minimize at the source Isolate/enclose the process or operator Increase distance from the source Change work practices Implement hearing conservation program Hearing loss is expensive! Many construction noise levels are high and require controls to reduce workers exposures. Control methods:
DOSH Consultation Services Safety & Health program review and worksite evaluation By employer invitation only Free Confidential No citations or penalties Letter explains findings Follow-up all serious hazards For additional assistance, you can call one of our consultants. Click below for local L & I office locations: http://www.lni.wa.gov/wisha/consultation/regional_consultants.htm
More Information DOSH: Noise Exposure – Hearing Loss NIOSH: Noise and Hearing Loss Prevention OSHA: Noise and Hearing Conservation National Hearing Conservation Association MSHA Noise Control Manual: Surface Mining Equipment MSHA Noise Control Manual: Surface Mining Equipment Institute of Noise Control Engineering of the USA