Silica Table 1 Respirator Lookup (OSHA 1926.1153)
Table 1 is the shortcut that lets you skip exposure assessment, and it is ALL OR NOTHING -- 1926.1153(c)(1) wants the controls, work practices AND respirator fully implemented, so doing part of it drops the job into monitoring against the 50 ug/m3 PEL. The duration column is a CLIFF at four hours, not a ramp: tuckpointing steps from APF 10 to APF 25 at four hours and one minute, which is a half mask becoming a PAPR -- a different purchase, fit test, and training record. And several rows change or vanish indoors, so a walk-behind saw needs nothing outdoors and APF 10 inside, while a drivable saw has no indoor row at all.
Formula and source
lookup: required respiratory protection and minimum assigned protection factor from Table 1, keyed on the task row, whether the work is outdoors or indoors/enclosed, and whether the task runs four hours or less per shift or more than four hours. Where the Table 1 controls are not fully implemented, or the row has no entry for the location, Table 1 does not apply and 1926.1153(d) governs against a 50 ug/m3 8-hour TWA PEL.
OSHA 29 CFR 1926.1153 Table 1 and 1926.1153(c)(1) and (d). A US federal regulation in the public domain, quoted directly.
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