Is the permitted exposure per visit or per day?

Per day. The limit is a total for an eight-hour period, so every approach draws on the same budget. Fifteen seconds can be the whole shift's allowance.

What is an effective irradiance?

A spectrally weighted one, where each wavelength is scaled by its relative hazard before summing. A broadband instrument reports a larger, different quantity.

Can I manage this with a timed procedure?

Almost never. A control requiring a person to limit themselves to a fraction of a second is not a control; enclosure, interlocks and distance work.

Why is the continuous limit so small?

It spreads the daily budget over 28,800 seconds. That puts it far below what an industrial lamp leaks through even a modest gap.

UV Curing calculator

UV Safety Exposure Calculator: A Daily Budget, Not a Per-Visit Allowance

Turn an exposure limit and a measured stray irradiance into permitted time, then share it across the day. Enter the limit, the stray irradiance, a safety margin and the number of approaches.

What this calculator does

Permitted UV exposure for a whole working day, split across every approach an operator makes.

Formula used

Derated limit = exposure limit ÷ (1 + safety factor ÷ 100)
Permissible exposure per day = derated limit ÷ stray irradiance
Seconds per exposure event = permissible exposure per day ÷ events per day
Base time to the limit = exposure limit ÷ stray irradiance
Stray irradiance allowing 8-hour presence = derated limit ÷ 28,800

Inputs explained

Effective UV Exposure Limit: Applicable eight-hour effective-irradiance limit for actinic UV.
Measured Stray Irradiance: Spectrally weighted effective irradiance at the operator position.
Safety Margin Above Limit: Margin held below the limit; it shortens time, not exposure.
Exposure Events per Day: Times a shift someone is in the field: jams, loading, inspection.

How to use the result

Best suited to checking a position's daily exposure budget, setting the attenuation a guard must achieve, showing why timed access is not a control.
This is arithmetic for a risk assessment, not an exposure assessment or compliance determination. Covers one actinic UV limit; separate near-UV and eye limits can also apply. Ignores reflected UV, the usual reason a position measures high.

Common questions

Is the permitted exposure per visit or per day? Per day. The limit is a total for an eight-hour period, so every approach draws on the same budget. Fifteen seconds can be the whole shift's allowance.
What is an effective irradiance? A spectrally weighted one, where each wavelength is scaled by its relative hazard before summing. A broadband instrument reports a larger, different quantity.
Can I manage this with a timed procedure? Almost never. A control requiring a person to limit themselves to a fraction of a second is not a control; enclosure, interlocks and distance work.
Why is the continuous limit so small? It spreads the daily budget over 28,800 seconds. That puts it far below what an industrial lamp leaks through even a modest gap.

Last reviewed 2026-10-01.