Noise Monitoring & Your Hearing Conservation Program

Noise Monitoring & Your Hearing Conservation Program Monitor noise exposure at your Mine site using a Sound Level Meter or Dosimeter, and develop a Hearing Conservation Program, Michigan Mine Safety & Health Training Program

Introduction 30 CFR Part 62 is the new MSHA Noise Standard. The following presentation provides current information on this regulation, and is based on material that was presented to Michigan mine operators in hands-on noise sampling workshops in 2001. No specific claims are made concerning the accuracy of the information presented here.

Printed Materials Needed for this Presentation. • Printed Materials • There are hardcopy forms, tables and examples that go with this presentation. Make sure they are available. • Please note that the MSHA Noise standard does not dictate the format of forms. The forms presented here are suitable for recording purposes, but you may design your own. • The Printed Materials we've provided have been numbered in the order that they are presented. • Form numbers are in the upper right-hand corner of the form. • Some forms consist of more than one page.

Minimum Equipment Needed for this Presentation. • A slow-response 'A' scale Sound Level Meter (SLM) • Make sure you have the manufacturer’s instructions. • SLMs may be purchased for as little as $40 from electronics stores. • Field Calibrator for the SLM • Instrument Calibrators confirm the accuracy of readings.

Other Equipment Included in this Presentation • Dual-Threshold Dosimeter • Simultaneously measures Action Level & PEL noise doses. • Must be able to be set to slow response on the 'A' scale. (This is the default setting for most dosimeters.) • Field Calibrator for Dosimeter.

Purpose of this Presentation • Objectives • To provide you with basic Noise Hazard Information • To show you how to do proper Noise Sampling, Noise Dose Calculation, and Record Keeping. • To prepare you to administer a Hearing Conservation Program (HCP) meeting MSHA's requirements. • Regulations of Concern • Noise Sampling - CFR 30 § 62.110 • Hearing Conservation Program - CFR 30 § 62.150

Noise Basics • The two factors that determine how hazardous noise is are: • Intensity (Loudness) measured in dBA • Time of Exposure measured in Hours and Minutes • The louder the noise, the more hazardous it is. Also, the longer the exposure time, the more hazardous the noise is. • A “Noise Dose” combines both loudness and time and is a convenient way of describing the relative hazard of the noise.

Noise Basics Loudnessis measured using a logarithmic scale. This means that a 10 decibel increase does not simply add 10 to the previous level. It multiplies the previous level by 10. Threshold of Hearing 0 dBA Quiet Room 45 dBA Conversation 55 dBA = 45 dBA x 10 Car (50 mph at 50 ft) 65 dBA = 45 dBA x 100 End Loader (In Good Cab) 75 dBA = 45 dBA x 1,000 Haul Truck (In Good Cab) 85 dBA = 45 dBA x 10,000 Crusher 95 dBA = 45 dBA x 100,000 Old Dozer (No Cab) 105 dBA = 45 dBA x 1,000,000 Air Track Drill (No Controls) 115 dBA = 45 dBA x 10,000,000 115 dBA has 10 million times more sound energy than 45 dBA and is capable of causing 10 million times more damage to hearing.

Noise Basics Allowable Noise exposure is based on Noise Dose. Noise Dose is expressed as a percentage of the allowable limit. How high it goes depends on both noise intensity and time of exposure to noise. Louder (More dBA) = More Noise Dose Longer (More Time) = More Noise Dose Absolute Quiet = 0% Noise Dose. 85 dBA for 8 Hrs = 50% Noise Dose. 90 dBA for 8 hrs = 100% Noise Dose. 95 dBA for 8 Hrs = 200% Noise Dose. 95 dBA for 12 Hrs= 300% Noise Dose.

Noise Basics Different combinations of Loudness and Time can produce the same Noise Dose. The following combinations can all produce about 75% Noise Dose. 84 dBA for 14 Hrs = 76% 85 dBA for 12 Hrs = 75% 87 dBA for 9 Hrs = 74% 88 dBA for 8 Hrs = 76% 93 dBA for 4 Hrs = 76% 95 dBA for 3 Hrs = 75% 98 dBA for 2 Hrs = 75% 103 dBA for 1 Hr = 76% 108 dBA for 30 Min = 76% 113 dBA for 15 Min = 76% Note: this table is based on using the 80 dBA (Low) threshold.

Noise Dose Table For the next several slides, refer to the Noise Dose Table in your printed materials. This is Table 1. A Noise Dose table is used to look up the Noise Dose when 'noise-level & exposure-time' are known. (Please note that the table shown in the following slides are not an exact duplication of the real Noise Dose table.)

Exposure Time Exposure times (in Hours) are listed across the top of the table. (Shown here in red.) NOI SE LEVEL IN dBA Exposure Time (Hours) .25 .5 1 2 3 4 5 6 7 8 9 10 11 12 85 86 87 88 89 90 91 92 93 94 95

Noise Levels Noise Levels (in dBA) are listed down the left side of the table. (Shown here in green.) NOI SE LEVEL IN dBA Exposure time in Hours .25 .5 1 2 3 4 5 6 7 8 9 10 11 12 85 86 87 88 89 90 91 92 93 94 95

Estimating a Noise Dose Using the Table 1. Measure the Decibel Level. (We will discuss methods for doing this later.) 2. Measure or estimate Exposure Time. 3. The Noise Dose is found at intersection of Decibel Level and Exposure Time. (Yellow Box) NOI SE LEVEL IN dBA Exposure time in Hours .25 .5 1 2 3 4 5 6 7 8 9 10 11 12 85 86 87 88 89 90 91 92 93 94 95 Noise Dose for 92 dBA for 6 hours

Using Noise Dose Table if Noise Levels vary. 1. If Noise Levels vary, divide shift into separate tasks. 2. Determine Dose for each task, then add the doses. NOI SE LEVEL IN dBA Exposure time in Hours .25 .5 1 2 3 4 5 6 7 8 9 10 11 12 85 86 87 88 89 90 91 92 93 94 95

REVIEW 1. Loudness is measured in dBA Quiet Room = 45 dBA Crusher = 95 dBA Air Track Drill = 115 dBA 2. Noise Dose = Loudness + Exposure Time Quiet (45dBA)for 8 Hrs = 0% Noise Dose Crusher (95dBA) for 8 Hrs = 200% Noise Dose Air Track Drill (115dBA) for 8 Hrs = 3,200% Noise Dose (The dBA level alone does not define noise hazard!) 4. Use Noise Dose Table to determine the hazard. 5. Noise Dose defines the noise hazard.

Noise Table Exercises (Answers on next slide.) Use the Noise Dose Table to figure out the Noise Dose for the following conditions: 1) Noise exposure is 88 dBA for 10 Hr What is Noise Dose ? 2) Noise exposure is 84 dBA for 4 Hrs and 94 dBA for 6 Hrs. (Remember: Figure the two noise doses separately and then add them.) What is the total Noise Dose ?

Noise Table Exercises - Answers 1) 88 dBA for 8 hours = 95% Noise Dose 2) 84 dBA for 4 hours, plus 94 dBA for 6 hours = 152%

Noise Table Exercises 3) Noise exposure is 79 dBA for 2 Hrs, 92 dBA for 3 Hrs, 81 dBA for 3 Hrs, 87 dBA for 30 Min, 90 dBA for 1 Hr, and 82 dBA for 30 Min. What is Noise Dose ?

Noise Table Exercises - Answer Answer to Exercise 3 79 dBA is under 80 dBA and is not counted toward the Noise Dose. The Noise Dose is obtained by adding the rest of the calculated doses is 79%.

Time Weighted Average (TWA8) The 'TWA8' is the Noise Level (dBA) which, if constant over 8 hours, would result in the same Noise Dose as the one calculated using the actual exposure time. Example: If a worker's Noise Dose from a 10 hour shift is 400%, what constant Noise Level (in dBA) over 8 hours would produce the same Dose? The answer is on the Noise Dose Table. Find "400" in the the "8 hour" Exposure Time column. Follow the row left to the Noise Level, which, in this case, is 100 dBA. The TWA8 value for any Noise Dose equaling 400% is 100 dBA .

Time Weighted Average (TWA8) - Continued Why use TWA8? Why not just use Noise Dose. Because the "TWA8" (which is expressed in dBA, rather than a percentage) is easier to use when applied to noise controls. Example: If one knows that the noise level in an area is kept below 90 dBA, for the full 8 hour work shift, then the 90dBA PEL has not been exceeded. Trying to think of this in terms of percentages is awkward. Action Level = 85 dBA (TWA8) Permissible Exposure Limit = 90 dBA (TWA8) Double Hearing Protection Level = 105 dBA (TWA8)

Noise Sampling And Hearing Conservation Program To obtain the full benefit of this section, make sure any noise sampling equipment you have is at hand.

§ 62.110 - Noise Exposure Assessment “The mine operator must establish a system of monitoring that evaluates each miner’s noise exposure sufficiently to determine continuing compliance with this part.” Note that 'monitoring' is not the same thing as 'sampling'. Self-sampling is only one of several types of 'monitoring' allowed by the standard. Other types of monitoring can include the following: 1. MSHA compliance sampling. (MSHA does the sampling.) 2. Equipment Manufacturer Specifications. (The equipment manufacturer does the sampling.) Regardless of the method, adequate records must be kept to prove that monitoring is being done.

How Often Is Noise Sampling Required ? • There is no mandatory sampling schedule. However, employee noise exposure records must accurately reflect the current noise conditions at the mine. • The mine operator must decide whether existing records (Self sampling, MSHA sampling, Manufacturer Specs., etc.) reflect current conditions. • If noise exposure has not changed, further sampling may not be needed.

Noise Sampling Two types of instruments commonly used for measuring noise are: • Sound Level Meter (SLM) • Cost as low as $40. Takes single noise measurements. (Because of this, a great deal of work must be done to calculate Noise Doses.) • Noise Dosimeter • High-cost instrument ($2000 and up). Takes measurements constantly and does all the work of calculating Noise Dose. • Your printed documentation includes detailed sampling checklists for both an SLM and a Noise Dosimeter.

Sound Level Meter (SLM) • Sound Level Meter (SLM) • Only gives instantaneous Noise Level readings. • The readout is in dBA. • Normally used to spot check Noise Levels. • Can be used to determine Noise Dose (with calculations). • The accuracy is ± 2 dBA. • Readings tend to err on the low side. Add 2 dBA to SLM readings before recording them. • Always read manufacturers instructions for proper SLM operation.

Dosimeter Always be familiar with manufacturer's instructions for proper operation. A typical dosimeter is usually capable of displaying the following information: • Run Time From Start Of Sampling • Low Threshold (Action Level) Noise Dose • Low Threshold Average Noise Level • High Threshold (PEL) Noise Dose • High Threshold (PEL) Average Noise Level • Sound Level Meter (Readout in dBA) • Maximum Noise Level Over A 1-Second Period • Time After Start Of Sampling When Max 1-Second Noise Level Occurred • Maximum Noise Level Over 1/16 Second Period • Projected 8-Hr Noise Dose • Time After Start Of Sampling When Noise Level Greater Than 115 dBA Occurred

SLM Exercise 1- Calibration For these Exercises you will need a calibrator. This can be either be a single or a multiple noise level calibrator. You will also need your Sound Level Meter (If you have a Dosimeter, switch it to SLM mode.) 1. Insert instrument microphone into the calibrator. 2. Turn on instrument and set it to read on the 'A scale' and at the 'slow response' setting. If you are using a dosimeter, switch it to Sound Level Meter (SLM) Mode. 3. Turn the calibrator to the lowest dB level. What is the Noise Level ? Your instrument should read within ± 1 dBA of the level indicated on the calibrator. 4. If your calibrator is a multi-noise level calibrator, repeat the above step for all noise levels on the calibrator.

SLM Exercise 1- Calibration Continued • You have just calibrated your Sound Level Meter. • Calibrate your instrument whenever you do noise sampling. • One Pre-Sampling Calibration and One Post- Sampling Calibration per day is acceptable. • If the SLM readout is within ± 1 dBA of calibrator setting, then instrument is reading accurately.

SLM Exercise 2 - Proper fit 1. Turn the calibrator on (Any Noise level will do). 2. Leave microphone in the calibrator What is the Noise level? It should be within 1 dBA of Noise level indicated on the calibrator. 3. With the calibrator on, slowly remove the microphone. What happens to the Noise level? It should drift down. This illustrates the need for a proper fit between the calibrator and instrument. Calibrators are usually designed to be used with only one type of instrument. Some calibrators come with special collars or fittings that allow them to be used with different instruments. 4. Always follow the calibrator manufacturer's recommendations.

Using A Sound Level Meter (SLM) 1. Set the SLM to read on the 'A' scale at 'Slow Response'. 2. Always put the windscreen over the microphone. Wind noise can seriously effect accuracy. Windscreens are precision manufactured from special materials. Do not use a substitute. 3. If the needle (analog readout) or the number (digital readout) is bouncing on the SLM, take the highest value as your official reading. 4. Add 2 dBA to this value before recording it. 5. Take frequent measurements at different times of the day, and whenever the task or the noise exposure changes. 6. Hold SLM at arm’s length away from your body. Point the microphone up. Do not place your body between the SLM and the noise source and, do not place the SLM between your body and the noise source. 7. If measuring personal exposure, hold SLM next to subject’s ear on the “Noisiest” side. 8. Document, Document, Document

SLM Documentation Forms • Your printed material includes SLM documentation forms. (See Blank Forms 1.1 thru 2.2, and filled out Example Forms 3.1 thru 6.2) • Always record your name, date, location, time, noise sources, noise controls, work activity, SLM data, and calibration. • If you are simply spot checking noise levels, you can record this information on Table A of Form 1, and nothing further need be done. • If you are measuring personal noise exposure, you must: • Complete Table A on Form 1.1, 1.2 • Complete Table B on Form 1.2 • Complete Entire Form 2 (both 2.1 and 2.2) • Instructions for filling out forms are on the forms.

SLM Documentation - Sample Forms 3.1, 3.2 Loader Operator • Note that in table A, fractional dBA’s are rounded up to the next whole number. • Note the number of sound level readings taken and the accompanying activity documentation. • The more thoroughly you document the monitored activity, the more accurate will be your final estimate of noise exposure. • Measure often.

SLM Documentation - Sample Form 3.2 Loader Operator - Continued Go to Table B On Form 3.2. The estimated total shift times spent at various noise levels are recorded here. Note that any readings from Form 3 that were below 80 dBA were not counted. Noise Level Total Estimated Shift Exposure time 80 dBA ……………………...……..1 hr. 83 dBA (1:00 + 2:00 + 3:00)……. 6 hr. 84 dBA ……………………...……..1 hr. 85 dBA ……………………...……..1 hr. Remember: The more measurements made, the more accurate the estimates.

SLM Documentation - Sample Forms 5.1, 5.2 Crusher Operator • In this example, the job of Crusher Operator is more complex than the Loader Operator. Therefore, it is even more important to measure often and thoroughly document the activity. (Table A)

SLM Documentation - Sample 1b Continued Crusher operator - Continued Go to Form 5.2, Table B. The estimated total shift time at the various as noise levels are recorded as follows. Noise Level Total Shift Exposure Time 83 dBA for 2:15 ………………………….rounded up to 3:00 84 dBA for 1:15 + 1:00 + 3:50 ...……….6:00 87 dBA for 0:15 ………………………….0:15 92 dBA for 0:45 + 0:40 ..………………..rounded up to 2:00 112 dBA for 0:03 ...………………………rounded up to 0:15

Figuring the Noise Doses from SLM Data How much noise is “TOO MUCH”? Two Noise Limits are defined in the Part 62 Noise Rule: • Action Level (AL) • Permissible Exposure Limit (PEL)

New Noise Rule - Action Level The minimum Noise Dose at which you must take action. The Action Level is defined as a 50% Noise Dose (using the 80dBA Low Threshold instrument setting), which is equal to a TWA8 of 85 dBA The Action Level Noise Dose includes the all noise between 80 dBA and 130 dBA called the Low Threshold Noise Dose. If a miner's Noise Exposure over an entire work shift equals or exceeds the 50% Action Level, the miner must be enrolled in the company's Hearing Conservation Program as per §62.150

New Noise Rule - Permissible Exposure Limit Permissible Exposure Limit (or PEL) is defined as a 100% Noise Dose, which is equal to a TWA8 of 90 dBA. The PEL Noise Dose includes all noise between 90 dBA and 140 dBA This is called the High Threshold Noise Dose. If a miner's exposure exceeds the PEL : • Feasible engineering and administrative controls must be applied. • The miner must enroll in the company's Hearing Conservation Program as per §62.150. • Double hearing protection must be worn if Noise Dose is higher than 800% (where the TWA8 = 105 dBA.) • No exposures above 115 dBA are allowed (based on a 30 second average reading.)

Sampling for the Action Level and the PEL • Sampling must include Action Level Noise Dose AND PEL Noise Dose. • The Action Level Noise Dose must include all noise from 80 dBA to 130 dBA (80 dBA Threshold). • The PEL Noise Dose must include all noise from 90 dBA to 140 dBA (90 dBA Threshold) • For a Sound Level Meter, use the Noise Dose Table. (For the PEL use only the Noise Level values above 90 dBA. The Action Level uses the entire chart.) • If you have a Dosimeter, it must be capable of doing measurements for both PEL and AL.

Figuring Noise Doses • Forms 2.1 & 2.2 are the blank Sound-Level-Meter Noise Dose calculation forms. • See Loader Operator example - Forms 4.1/ 4.2. • The estimated exposure times at various decibel levels from form 3.1 have been transferred to the appropriate spaces on Forms 4.1/4.2 • The same has been done for the Crusher Operator on Forms 6.1/6.2.

Noise Doses for the Loader Operator • The Noise Dose Table is then used to figure the Noise Dose for each Noise Level. This Noise Dose is then recorded in the third column of Forms 4.1/4.2 for the Loader Operator (forms 6.1/6.2 for the Crusher operator.) • When you are calculating your own Noise Doses, follow the same steps as these examples. • Finally, add all the separately calculated Noise Doses to get the final Noise Dose for the full work shift.

Dosimeter Sampling • Noise Dosimeters: • Measure accumulated exposure to varying noise levels over time period. • Give readouts in % Noise Dose. • Most Dosimeters also provide: • Sound Level Meter (SLM) capability. • Average Noise Level. (Time Weighted Average) • Projected 8 Hr Noise Dose.

Dosimeter Exercise #1 This exercise illustrates how quickly the noise dose can accumulate at high noise levels. 1. Insert microphone into calibrator. 2. Turn on dosimeter. 3. Set calibrator to 124 dB (or as high as it will go). 4. With dosimeter set to display High-Threshold Noise Dose %, turn the calibrator on for exactly 5 minutes. 5. While waiting, watch how fast the Noise Dose is adding up. (Note:Some dosimeters may require you to press the 'Noise %' button continuously to get a running readout.) 6. Turn the calibrator off after 5 minutes. 7. The Noise Dose would be somewhere around 125% for a calibrator set to 124 dB and 17% for a calibrator set to 110 dB.

Dosimeter Exercise #2 This exercise demonstrates the ability of a dual-threshold dosimeter to distinguish between Low Threshold and High Threshold Noise Doses. 1. Write down the High Threshold Noise dose you obtained from the previous exercise. (Do not clear or reset the dosimeter.) 2. Leave microphone in the calibrator and switch the dosimeter display to SLM. 3. If calibrator is multi-level, turn calibrator to the lowest dB setting. 4. Slowly remove the microphone until the dosimeter display reads 83 dB. 5. Try to hold the microphone in this position for exactly 5 minutes. 6. Switch the dosimeter display back to High Threshold Noise Dose %. There should be no increase in the Noise Dose % because the noise being measured is below the High Threshold Limit of 90 dBA.) 7. Now, switch the dosimeter display to Low Threshold Dose %. This reading should be slightly higher than the High Threshold Noise Dose because the noise being measured is above the Low Threshold Limit of 80 dBA.

In Review • Dosimeters are “Dual Threshold” • The Noise Dose is accumulated simultaneously at both 80 dBA and 90 dBA thresholds: • 80 dBA is the threshold for the “Action Level” • 90 dBA is the threshold for the “PEL”

Noise Sampling with a Dosimeter 1. Make sure the microphone is inserted into the Windscreen. 2. Clip the dosimeter to the subject’s belt, or put it in the subject's pocket. 3. Clip the microphone to the center of the shoulder, pointing up. (Pick the subject's “Noisiest” shoulder.) 4. If necessary, use clips or duct tape to attach the microphone cord to the clothing. 5. Document, Document, Document

Dosimeter Documentation - Form 7 • Always record your Name, Date, Employee Name, Location, Time On, Time Off, Noise Sources, Noise Controls, Work Activity, Hearing Protectors, Dosimeter Data, and Calibration • Throughout the sampling period, record the accumulated Noise Dose as often as the task changes or at least every 2 hours if the task does not change. • Spot check the Noise Levels with an SLM (to verify Dosimeter readings). • Record the Final (or Projected) Noise Dose.

Projected Noise Dose • You can sample for less than 8 hrs, and the dosimeter will calculate what an 8 hr exposure would beifthenoisehadcontinuedatthesameaveragelevel. • This is called the Projected Noise Dose. • It is less accurate than sampling for a full 8 hours. • It does not project for 10 hr, 12 hr, or 14 hr, etc. work shifts. These you must estimate yourself or sample the entire shift. Projected Noise Dose Exercise: • Place the microphone in the calibrator. • Turn on the dosimeter and the calibrator. • Switch dosimeter to 'Projected 8 hour Noise Dose'. • Depending on the Noise Level that the calibrator is set at, you will now get an 8 hour projected estimate of the Noise Dose for that Noise Level.

Noise Monitoring & Your Hearing Conservation Program