Noise

• OSHA uses a 5 dB doubling rate (aka, exchange rate).  For every 5dB increase, maximum time until 100% dosage halves.
• Peak: At no point during an employee's work shift should they be exposed to a sound pressure level over 140dB C-weighted.
  • NOTE: I previously had non-weighted (otherwise known as Z-weighting) because no OSHA reference material or publications seen by me had reference to weighting as it applies to peaks. However, the ACGIH and others set this limit with C-weighting.
• Error Factor → The error of the dosimeter must be factored in to the consideration of a violative condition.
  • For example, the dosimeters used at KYOSH are Type II dosimeters. This indicates an error of 2 dB.
  • A Type I dosimeter has an error of only 1 dB.
• Shift Length Considerations: Unlike most other standards, the length of an employee's shift affects how noise exposure should be considered.
  • First off, the PEL is not affected by the length of the shift.
  • However, the Action Level (AL) is proportionally affected by the length of the shift. Because the Hearing Conservation Program (HCP) portion of 29 CFR 1910.95 was an amendment to the original standard, different considerations are in place. This includes the fact that sound level pressures (SLP) all the way down to 80 dBA are included in exposure calculations.
  • The AL is reduced for shifts over 8 hours, according to the following equation:
    • AL= 16.61 log [50/(12.5*hours)] + 90
    • Here is a table showing a few examples: {| class="wikitable" !Exposure Time (Hours) !Action Level (dBA) |- |8 |85 |- |9 |84.2 |- |10 |83.4 |- |12 |82.1 |- |16 |80 |}

Noise Standards

For Noise Exposure — 1910.95(a) and (b)

• Exchange (Doubling) Rate: 5 dB
• Criterion Level: 90 dBA
• Threshold: 90 dBA*

For Hearing Conservation — 1910.95(c) (General Industry amendment; not Construction)

• Exchange (Doubling) Rate: 5 dB
• Criterion Level: 90 dBA
• Threshold: 80 dBA*

*See OSHA Tech Manual Section III, Chapter 5, I.A.3. and I.A.4.

Standard Threshold Shift (STS)

An STS is a change in hearing threshold relative to the baseline audiogram of an average of 10 dB or more at 2000, 3000, and 4000 Hz in either ear.

• When a STS has occurred and the employee’s hearing level is at least 25 dB above audiometric zero in the same ear, the hearing loss is recordable on 300 logs.

• If a STS has occurred, you set this new audiogram as the Revised Baseline Audiogram.

Sampling

Substance Codes

8111	Hearing Conservation Program (Action Level @ 50% dose / 85 dBA)
8110	Engineering Controls (PEL @ 100% dose / 90 dBA)

Edge eg5 Noise Dosimeter (3M)

Detection Management Software

★ This software is required when changing settings on the device, including setting date/time.  There is no way to do this from the device itself.

Procedures for setting/checking configuration in DMS

1. Set each of the eg5 dosimeters into the charging base.
2. Power on each dosimeter. (NOTE: Don't skip this part. Turn it on!)
3. Ensure the USB cable is plugged into both the charging base and the computer.
4. Open the 3M DMS software.
5. Click the "Setup" button, which will take you to the Setup page.
6. On the left-hand side, choose "Noise Dosimetry" under "Family," then "Edge" under "Instrument," and then "Edge 5" under "Model."
7. In the pane immediately to the right, it should list every Edge dosimeter you have correctly set into the charging base and turned on. Each dosimeter listed should have a green check next to it indicating that it's detected.
8. Importing a saved configuration
   1. Under "Configuration Profile Management" on the right, right-click somewhere in the empty space.
   2. Choose "Import Profile."
   3. Select the pre-configured profile you want to import.*
   4. Once imported, select it and choose "Load."
   5. Optional: You can also set it as default.
9. Setting the configuration
   1. Check the box next to the dosimeter(s) whose configurations you want to set.
   2. Starting with either an imported profile or one that is built-in, make any modifications you'd like using the tabs on this page (Dosimeter, Display, Security, etc.).
   3. Scroll down toward the bottom of the Setup screen and click "Set Configuration."
   4. This can take some time, so be patient. Check the progress in the text window near the bottom.
10. Setting date and time
    1. Scroll all the way down under the Setup screen; OR click on the word "Setup."
    2. You'll see some additional blue bars with icons next to both "Download" and "Miscellaneous Setup."
    3. Click anywhere on the words Miscellaneous Setup.
    4. Check the boxes next to the dosimeters you're wanting to set.
    5. Choose "Current System Time."
    6. Click "Set Date-Time."

*There is a pre-configured configuration file that you can import into the DMS.  This configuration file is saved in the IH Shared folder on the H drive:  H:\IH Shared\OSH Reference\Equipment\Configuration Files\Edge_Dosimeter_Config_ky.xml

Basic Qualities of Sound

★ This section is taken largely from Section III, Chapter 5, of the OSHA Technical Manual (OTM). The OTM is a fantastic resource for the science behind the inspections, sampling, and analysis of what Industrial Hygienists do in protecting the Commonwealth's workers. Refer to it and refer to it frequently.