Subpart C
You must record a hearing loss on the OSHA 300 Log when an employee's audiogram shows a work-related Standard Threshold Shift (STS) in one or both ears and the employee's total hearing level in the same ear(s) is 25 decibels (dB) or more above audiometric zero (averaged at 2000, 3000, and 4000 Hz). See Recording criteria in 1904.10(b) and the basic requirement in 1904.10(a).
A Standard Threshold Shift (STS) is an average change in hearing threshold of 10 dB or more at 2000, 3000, and 4000 Hz in one or both ears compared to the employee's baseline audiogram. This definition comes from the occupational noise standard at 29 CFR 1910.95(g)(10)(i) and is summarized in 1904.10(b)(1).
You compare an employee's current audiogram to that employee's baseline audiogram; if the employee already has a previously recorded hearing loss, you compare the current audiogram to the employee's revised baseline that reflects the prior recordable case. See 1904.10(b)(2)(i) and 1904.10(b)(1).
You determine the employee's total hearing level by averaging the hearing levels at 2000, 3000, and 4000 Hz on the employee's current audiogram and comparing that average to audiometric zero; if the average is 25 dB or more above audiometric zero in the same ear(s) as the STS, the case is recordable. See 1904.10(b)(2)(ii) and 1904.10(b)(3).
Yes—you may age-adjust the employee's current audiogram results when determining whether an STS has occurred by using Tables F-1 or F-2 in appendix F of the noise standard [29 CFR 1910.95]. However, you may not use age adjustment when deciding whether the employee's total hearing level is 25 dB or more above audiometric zero. See 1904.10(b)(3) and 1910.95.
No—not if you retest within 30 days and the retest does not confirm a recordable STS: you are not required to record the case. If the retest confirms the recordable STS, you must record the hearing loss within seven calendar days of the retest. If later testing shows the STS is not persistent, you may erase or line-out the recorded entry. See 1904.10(b)(4).
No—there are no special rules specific to hearing loss; you must apply the general work-relatedness rules in [1904.5] to determine whether the hearing loss is work-related. If an event or exposure in the work environment caused, contributed to, or significantly aggravated the hearing loss, consider the case work-related. See 1904.10(b)(5) and 1904.5.
No—if a physician or other licensed health care professional determines, applying the rules in [1904.5], that the hearing loss is not work-related or that occupational noise did not significantly aggravate it, you are not required to record the case on the OSHA 300 Log. See 1904.10(b)(6) and 1904.5.
When you enter a recordable hearing loss on the OSHA 300 Log, check the column for hearing loss on the 300 Log to indicate the case involves a hearing loss. See 1904.10(b)(7).
You calculate an STS by comparing the average hearing thresholds at 2000, 3000, and 4000 Hz on the current audiogram to the same average on the baseline audiogram; an increase (worsening) of 10 dB or more in that averaged value in one or both ears is an STS. See 1910.95(g)(10)(i) and 1904.10(b)(1).
Yes—an STS in one ear can make the case recordable if that same ear's average hearing level at 2000, 3000, and 4000 Hz is 25 dB or more above audiometric zero. The rule counts STS in one or both ears and requires the 25-dB threshold in the same ear(s). See 1904.10(b).
No—you may use Tables F-1 or F-2 in appendix F of [1910.95] to age-adjust the current audiogram when determining whether an STS has occurred, but you may not use age adjustment to determine whether the employee's total hearing level is 25 dB or more above audiometric zero. See 1904.10(b)(3) and 1910.95.
If later audiometric testing performed under the 1910.95 noise standard shows the STS is not persistent, you may erase or line-out the previously recorded OSHA 300 Log entry for that hearing loss. See 1904.10(b)(4).
For recordkeeping, the employee's "total hearing level" is the average hearing level at 2000, 3000, and 4000 Hz on the current audiogram compared to audiometric zero; that averaged value is used to determine whether the hearing level is 25 dB or more. See 1904.10(b)(2)(ii) and 1904.10(b)(3).
A revised baseline is the audiogram that reflects the employee's previous recordable hearing loss case and is used as the comparison audiogram for future STS determinations—i.e., if the employee already has a recordable loss, compare the current audiogram to the revised baseline rather than the original baseline. See 1904.10(b)(2)(i).
Yes—software-generated or electronic forms can be used as substitutes for OSHA Form 300 and Form 300A so long as they meet the equivalent-form requirements in the recordkeeping rules and can produce equivalent forms for access and inspection. See the OSHA interpretation Software-generated OSHA recordkeeping forms and general recordkeeping 1904.
Apply the general work-relatedness rules in [1904.5]: a condition is work-related if an event or exposure in the work environment caused, contributed to, or significantly aggravated it; travel-status rules (including the "home away from home" exception) can affect that determination. See 1904.5 and the OSHA interpretation on travel-status work-relatedness in the motor vehicle fatality letter at https://www.osha.gov/laws-regs/standardinterpretations/2024-06-12 for practical examples of how travel affects work-related determinations.
No—you only record the case if the STS and the 25-dB total hearing level occur in the same ear(s); both conditions must exist in the same ear(s) for the case to be recordable. See 1904.10(b).
If you retest the employee's hearing within 30 days of the first test and the retest does not confirm a recordable STS, you do not have to record the case; if the retest confirms an STS, you must record the case within seven calendar days of that retest. See 1904.10(b)(4).
The evaluation for both STS and the total hearing level uses the hearing thresholds at 2000, 3000, and 4000 Hz—STS is based on a 10 dB average change at these frequencies and the 25-dB total hearing level is the average at these same frequencies compared to audiometric zero. See 1910.95(g)(10)(i) and 1904.10(b)(3).
No—the age adjustment may be used only to determine whether an STS has occurred; you cannot use age adjustment when deciding whether the employee's total hearing level is 25 dB or more above audiometric zero, so if the unadjusted current audiogram average is less than 25 dB the case is not recordable even if age-adjusted values show an STS. See 1904.10(b)(3) and 1910.95.
If a physician or other licensed health care professional, applying the rules in [1904.5], determines the hearing loss is not work-related, you are not required to consider the case work-related or keep it recorded as work-related; follow the physician's determination consistent with 1904.10(b)(6) and 1904.5.