The permissible exposure limits (PELs) for personal exposure are as follows:
(a) The time-weighted average exposure limit (TWA).
(b) The short-term exposure limit (STEL). Exposures at the STEL must not be repeated more than four times a day. There must be at least 60 minutes between successive exposures at the STEL.
source: CGD 76-009, 43 FR 53683, Nov. 16, 1978, unless otherwise noted.
cite as: 46 CFR 197.515