OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

CPL 2-2.35A
May 8, 1984

MEMORANDUM FOR:  REGIONAL ADMINISTRATORS

FROM:            JOHN B. MILES, JR., Director
                 Directorate of Field Operations

SUBJECT:         Region III's Supplement to Noise Policy

For your information, I am forwarding to you the attached questions and answers relative to the noise policy which were developed by the Philadelphia Regional Office and reviewed by my staff.

If appropriate, please forward a copy of the attachment to the State designee.

 

Attachment (see next page)

 

 

March 30, 1984
(w/NO recommendations of 2/24/84 and modified re memo dated May 23, 1984))

QUESTIONS AND ANSWERS RELATIVE TO CPL 2-2.35A

 

1. Question: Does CPL 2-2.35A apply to construction noise inspections?

Answer: No.

2. Question: How should area offices handle open cases, contested cases, failures to abate (FTA), and petitions for modification of abatement (PMA)?

Answer: Handle these cases in accordance with the policy established by CPL 2-2.35A.

3. How should one cite for TWA's above dBA?

Answer: Cite for violating 29 CFR 1910.95(b)(1) whenever engineering or administrative controls are feasible. In addition, cite for violating (b)(1) when noise is below this level but above the permissible exposure limit, whenever controls are cost-effective or when there is documented hearing loss and there are no violations of the Hearing Conservation Amendment (HCA) that can be corrected to remedy the situation.

4. Question: Does the 100 dBA in F.1.a. of the CPL refer to an 8-hour TWA?

Answer: Yes

5. Question: What is the scenario of "no improvement" in the hearing conservation program (G.3.a.(2))?

Answer: If all HCA standards are met but progressive hearing loss in employees continues and the probable etiology is occupational noise exposure.

6. Question: Can the employer mandate a particular type of ear protection?

Answer: Yes. The employer may mandate that the employee only use the type which will provide sufficient attenuation of noise to prevent any hearing loss. If more than one type of hearing protection is adequate, however, then the employer cannot mandate which one of these the employee uses.

7. Question: Can the employer mandate a combination of a plug and a muff?

Answer: The attenuation provided by a combination of a plug and muff falls short of the algebraic sum of the attenuation of the individual devices. In certain circumstances where an employee's audiograms indicate STS's or progressive noise- induced hearing loss, however, the combination may be the only available means of enhancing the employee's protection. In such a situation the employer may mandate that the employee wear a combination of a plug and a muff.

8. Deleted (see follow-up memo dated May 23).

9. Question: If all conditions except (3) listed in the answer to question 8. exist, what shall our course of action be?

Answer: Cite a violation of 29 CFR 1910.95(b)(1). If the employer registers a preference for upgrading the hearing protection devices so as to meet condition (3), rather than instituting engineering or administrative controls, consider the violation corrected by such upgrading of the hearing protection devices.

10. Question: How should a CSHO calculate the hearing protector attenuation?

Answer: For a muff or plug obtain the NRR (calculate the laboratory based attenuation using the IHFOM or NIOSH procedures, when no NRR is available for the protector). Since the noise dosimeter gives you a TWA in dBA, subtract 7 dB from the NRR for spectral uncertainty pursuant to Appendix B in the hearing conservation amendment (HCA). Consider the following examples:

(1) given: TWA8 = 100 dBA

          Muff NRR = 20 dB

   solution:  Attenuation re CPL 2-2.35 is (20 -7)/2 =
              6.5 dB

              100 dBA TWA -6.5 dB = 93.5 dBA

   conclusion:  The protected TWA can be assumed to be
                93.5 dBA.  This hearing protection is not
                adequate for an 8-hour exposure.

(2) given: TWA      = 98 dBA

          plug NRR = 29 dB

   solution:  Attenuation re CPL 2-2.35 is

              (29 - 7)/2  =  11 dB

              98 dBA TWA -11 dB = 87 dBA

   conclusion:  The protected TWA can be assumed to be 87 dBA.
                This hearing protector is adequate if the
                employee does not exhibit STS or the employer
                is not invoking the van testing greater than
                6 month testing option. (1910.95(g)(5)(ii))

(3) given: TWA      = 110 dBA

          plug NRR = 29 dB

          muff NRR = 25 dB

          Employer requires dual protection.

   solution:

   (a) calculate field adjusted NRR for the better protector.

       (29 -7)/2 = 11 dB

   (b) for dual protection add 5 dB to this field-adjusted
       NRR.

       11 + 5 = 16 DB

   (c) calculate the protected TWA.

       110 dBA TWA -16 dB = 94 dBA

   conclusion:  The protected 8-hour TWA is 94 dBA.  This
   hearing protection is not adequate.  If feasible, engineering
   controls must be implemented.  Better hearing protection
   must be used.  If the employee shows STS, administrative
   controls or medical removal should be employed.

Remarks: In examples (1) and (3) the calculations indicate ear protection to be inadequate. If the employer can satisfactorially demonstrate that the protection he provides is better than these calculations, you may use his attenuation in place of the CPL method if the affected employees do not exhibit STS's. If you experience particular problems or the employer contests your calculation, consult with the ARA of Technical Support for assistance.

11. Modified (see memo dated May 23) to read:

Question: If the TWA is 100 dBA or less and engineering or administrative controls are less expensive than the cost of a HCP, but they will not drop the TWA to 85 dBA, should a citation for (b)(1) be issued?

Answer: Yes, if engineering/administrative controls are technically feasible and if either the employer does not have an ongoing hearing conservation program (e.g., at least three years of current annual audiograms) or there is evidence of hearing loss.

12. Question: What is a feasible engineering control?

Answer: An acoustical engineering control is feasible only if it is effective, efficient, and economical. By effective, it must reduce the noise source being controlled by 3 dBA or more. By efficient, it must not introduce obvious hazards or produce intolerable production, maintenance, and sanitation problems. Through CSHO field documentation and previous experience the efficiency of the control approach should be reasonably apparent for potential violations.

Supplement to Noise Policy

 

May 23, 1984

MEMORANDUM FOR:  REGIONAL ADMINISTRATORS

FROM:            JOHN B. MILES, JR., Director
                 Directorate of Field Operations

SUBJECT:         Region III's Supplement to Noise Policy

On May 8, 1984, I forwarded to you a copy of questions and answers relative to the Noise Policy which were developed by the Philadelphia Regional Office. This memorandum is to request that you delete question 8 since it is outdated and modify the answer to question 11 as follows:

11. Question:

If the TWA is 100 dBA or less and engineering or administrative controls are less expensive than the cost of a HCP, but they will not drop the TWA to 85 dBA, should a citation for (b)(1) be issued?

Answer:

Yes, if engineering/administrative controls are technically feasible and if either the employer does not have an ongoing hearing conservation program (e.g., at least three years of current annual audiograms) or there is evidence of hearing loss.