Safe 5120Industrial Hygiene Noise and Vibration Chapter 21

Safe 5120Industrial Hygiene Noise - History 100 Years – Noise Exposure results in permanent hearing Loss! 1918 – Vibration causes permanent damage to hands and fingers.

Safe 5120Industrial Hygiene Sound Wave

Safe 5120Industrial Hygiene Physics of Sound C = Speed of propagation λ = c/f C = speed f = frequency λ = wavelength

Safe 5120Industrial Hygiene Physics Frequency = 1000 cycles per second C = feet/sec (344 meters/sec) Λ = /125 hz =9.02 feet

Safe 5120Industrial Hygiene Physics Sound is pressure 1 P = 1 Newton/m2 P = Pascal L = 10Log(P/P ref ) 2 Pref = 20 µPa

Safe 5120Industrial Hygiene Physics Sound Pressure = 0.2 Pascals What is Sound level? L = 10Log(0.2/20 µPa) 2 L = 80 dB dB = decibels (deci = 1/10)

Safe 5120Industrial Hygiene Directional

Safe 5120Industrial Hygiene Sound dBA vrs dBC weighting A = close to human hearing C = Flat

Safe 5120Industrial Hygiene

Safe 5120Industrial Hygiene Noise Control Barriers Distance Isolation

Safe 5120Industrial Hygiene Limits 84 dBA 8 hours AF/DOD (4 dB) 90 dBA 8 hours OSHA (5dB) 85 dBA 8 hours TLV (3dB exhange) See Chapter 21, page 445 See TLV booklet page 117.

Safe 5120Industrial Hygiene Limits 90 dBA for 8 hours 95 dBA for 4 hours 100 dBA for 2 hours What is the limit for 30 minutes? 5 dBA exchange Rate

Safe 5120Industrial Hygiene Distance If a noise source is 96 dBA at 10 feet What is the intensity at 20 feet?

Safe 5120Industrial Hygiene Distance Answer: 90 dBA Calc: L =L- 20 Log(D2/D1) L = L -20 Log (20/10) L = L- 20 Log (2) L = L-20 (0.301) L = 96dbA dB = 90dBA Rule of Thumb: Double distance, drop 6 dB

Safe 5120Industrial Hygiene Noise Calc - Activity A noise source is 102 dBA (Measured) at 25 feet. What will the noise level be at 60 feet?

Safe 5120Industrial Hygiene Activity L = 20 Log(D2/D1) L = 20 Log (60/25) L =20 Log(2.4) L = 20 (0.38) 7.6 dB 102 dBA – 7.6 dBA = 94.4 dBA

Safe 5120Industrial Hygiene Controls Turn the Noise Source Place Barriers (Frequency dependant) Isolation/Absorption materials

Safe 5120Industrial Hygiene

Safe 5120Industrial Hygiene

Safe 5120Industrial Hygiene

Safe 5120Industrial Hygiene Plywood /32 nd 1/64th

Safe 5120Industrial Hygiene General Notes Lower Frequencies more difficult Specialized materials

Safe 5120Industrial Hygiene Hearing Exposure Effects: Tinnitus – Ringing, buzzing, whistle –Indicator of damaging noise exposure Acoustic Trauma – loss due to a sudden intense noise (Explosion) Threshold Shift – change in the response of hearing in certain frequencies

Safe 5120Industrial Hygiene Noise Induced Hearing Loss

Safe 5120Industrial Hygiene Hearing Loss, Sources

Safe 5120Industrial Hygiene Hearing Loss – Noise Induced Hearing Loss (NIHL

Safe 5120Industrial Hygiene Rules of Thumb Shout at 3 Feet Loud Voice at 1 foot It’s Hazardous Noise!

Safe 5120Industrial Hygiene Speech Interference Level SpIL = Limit to 55 dBA background Difficulty using phones, communicating

Safe 5120Industrial Hygiene Noise Measurement Hand-held Octave Band Analysis Graphic Level Instruments

Safe 5120Industrial Hygiene Moving the Source rotation

Safe 5120Industrial Hygiene Medical Examinations Baseline Periodic –Annual –48 hours noise free –Threshold shifts

Safe 5120Industrial Hygiene Medical Examinations Threshold shift determination is –Frequency Dependant –Age factors –smoking

Safe 5120Industrial Hygiene Noise Control Hearing Protection dbA dBA 27 dBA

Safe 5120Industrial Hygiene Noise Control 27 –33 dBA reduction

Safe 5120Industrial Hygiene Noise Control

Safe 5120Industrial Hygiene Noise Control Noise Source: 117 dBA, 2 hours V51Rs Noise Exposure:?

Safe 5120Industrial Hygiene Noise Exposure dbA = 90 dBA Adequate? In some cases, have to use plugs and muffs!

Safe 5120Industrial Hygiene Vibration Human exposure divided into: Whole Body Hand-arm vibration

Safe 5120Industrial Hygiene Vibration Causes: –Vibration induced White Finger (VWF) or –Raynauld’s syndrone

Safe 5120Industrial Hygiene Vibration Exposure: (Book) –8 Million workers

Safe 5120Industrial Hygiene Vibration - Charts

Safe 5120Industrial Hygiene Vibration 4 Hrs < 8 hrs g 2 hrs < 4 hrs hr < 2 hrs < 1 hr Duration m/s 2 gDelta > 16 hz may need special consideration! G = 9.81 m/sec

Safe 5120Industrial Hygiene Variations: UK 2.8 m/sec 8 hours Canada Same.

Safe 5120Industrial Hygiene Average Vibration Average Vibration: 9.0 m/sec 2 - Jackhammer (Time Limit?)

Safe 5120Industrial Hygiene Average Vibration After Training/Techniques: 5.5 m/sec2

Safe 5120Industrial Hygiene ELV = Exposure Limit Value EAV = Exposure Action Value

Safe 5120Industrial Hygiene Hand Direction

Safe 5120Industrial Hygiene Stage Assessment Table

Safe 5120Industrial Hygiene Table 4 Average latent periods for vibration-induced diseases in different occupations OccupationStage of VWFLatency (years) Foundry workerTingling Numbness Blanching Shipyard workerTingling Numbness Blanching Chain saw operatorNumbness4 GrinderBlanching13.7

Safe 5120Industrial Hygiene Table 2. Workers Potentially Exposed to Hand-Arm Vibration No. of Workers IndustryType of Tool 500,000ConstructionHandtools 200,000FarmingGasoline chain saws 14,000Metal workingHandtools 54,000Steel Furnace cleaning using powered handtools 30,000Lumber and woodGasoline chain saws 34,000Furniture manufacturingHandtools 100,000MiningPneumatic drills 250,000 Truck and auto manufacturing Handtools 64,000FoundriesHandtools Total1,246,000

Safe 5120Industrial Hygiene Controls Anti-vibration tools anti-vibration gloves Proper work practices –Keep hands warm Medical Surveillance

Safe 5120Industrial Hygiene Break