Permissible exposure (a), (b): protection is required when sound levels, measured on the A scale at slow response, exceed Table G-16: 90 dBA for 8 hours, 92 for 6, 95 for 4, 97 for 3, 100 for 2, 102 for 1 1/2, 105 for 1, 110 for 1/2 and 115 dBA for 1/4 hour or less. Mixed exposures are combined as C1/T1 + C2/T2 and exceed the limit when the sum exceeds unity; impulsive or impact noise should not exceed 140 dB peak. Above the table, feasible administrative or engineering controls must be used first, then personal protective equipment. Variations with maxima at intervals of 1 second or less are continuous. Hearing conservation program (c) to (n): required whenever exposures equal or exceed the action level, an 8-hour TWA of 85 dBA (a 50 percent dose), computed per Appendix A without regard to hearing protector attenuation. Monitoring (d): when information indicates exposure may reach 85 dBA, a monitoring program is implemented, with personal sampling where mobility, variation or impulse noise make area sampling unsuitable; all sound from 80 to 130 dB is integrated; instruments calibrated; repeated when changes may put more employees at or above the action level or make protectors inadequate. Exposed employees are notified of results (e) and may observe measurements (f). Audiometric testing (g), (h) at no cost by a qualified audiologist, otolaryngologist, physician or certified or competent technician: baseline within 6 months of first exposure at or above the action level (within 1 year with mobile vans, with protectors worn after 6 months until baseline), preceded by 14 hours without workplace noise (protectors may substitute); annual audiograms compared with baseline; a standard threshold shift is an average change of 10 dB or more at 2000, 3000 and 4000 Hz in either ear (age correction per Appendix F allowed); retest within 30 days permitted; written notice to the employee within 21 days of a shift determination, then fitting, refitting, training and referral unless a physician finds the shift not work related. Tests cover at least 500 to 6000 Hz each ear, in rooms meeting Appendix D, with audiometers per ANSI S3.6-1969: functional check before each day's use, acoustic calibration at least annually (Appendix E), exhaustive calibration at least every two years. Hearing protectors (i), (j): available free to all at or above 85 dBA, a choice of suitable types, training, initial fitting and supervision; mandatory for employees above Table G-16, and for those at or above 85 dBA without a baseline or with a threshold shift. Attenuation evaluated per Appendix B (NRR or NIOSH methods) to reduce exposure to 90 dBA, or to 85 dBA or below after a threshold shift. Training (k) annually for all in the program on noise effects, protectors and audiometric testing. The standard is posted and made available (l). Records (m): exposure measurements kept two years; audiometric records (name, job, date, examiner, last calibration, latest exposure assessment) for the duration of employment; background test room levels; access per 1910.1020; transfer to a successor. Appendices A to E are mandatory, F and G informational. Paragraphs (c) to (n) do not apply to oil and gas well drilling and servicing.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.