Work out permissible exposure limit check instantly with clear inputs, formula shown and shareable results.
Exposure limits assume a standard eight hour shift. For extended shifts the Brief and Scala model reduces the limit by (8/h) x ((24-h)/16), which accounts for both longer uptake and shorter recovery between shifts. Exposure at half the limit is generally treated as the action level at which controls and monitoring become mandatory.
Brief and Scala adjustment
Adjusted limit = PEL x (8 / hours) x ((24 - hours) / 16) for shifts over 8 hours
Exposure ratio
Ratio = measured concentration / adjusted limit
Preliminary estimate only. Occupational exposure assessment must be carried out by a qualified occupational hygienist using validated sampling methods and the limits adopted by your regulator.
Adjusted limit = PEL x (8 / hours) x ((24 - hours) / 16) for shifts over 8 hours. Exposure limits assume a standard eight hour shift.
Sampling and analytical variability mean a result at half the limit could genuinely be at the limit. The action level triggers controls before an exceedance is confirmed.
This calculator takes 3 inputs: Measured concentration, Permissible exposure limit, Shift length. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.