Permissible Exposure Limit Check Calculator

Work out permissible exposure limit check instantly with clear inputs, formula shown and shareable results.

About Permissible Exposure Limit Check Calculator

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.

Formulas

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

Worked example

With the default values below, Permissible Exposure Limit Check Calculator returns Exposure as share of the limit of 90.00%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Measured concentrationminimum 0 ppm: 45 ppm
Permissible exposure limitminimum 0.001 ppm: 50 ppm
Shift lengthaccepts 0.5–24 h: 8 h

Results

Exposure as share of the limit: 90.00% %
Shift-adjusted limit: 50.000 ppm
Exposure ratio against the adjusted limit: 0.9000
Assessment: Above the action level — monitoring and controls needed

Step by step

1Values used
2Brief and Scala adjustment
3Exposure ratio
4Exposure as share of the limit= 90.00 %
5Shift-adjusted limit= 50.000 ppm
6Exposure ratio against the adjusted limit= 0.9000
7Assessment= Above the action level — monitoring and controls needed

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
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.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

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.

Frequently Asked Questions

How is the Permissible Exposure Limit Check figure worked out?

Adjusted limit = PEL x (8 / hours) x ((24 - hours) / 16) for shifts over 8 hours. Exposure limits assume a standard eight hour shift.

Why is fifty percent of the limit significant?

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.

What values do I need to enter?

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.