Principles od assessment

MEASUREMENT METHODS


The choice of optical radiation measurement method depends on the following factors:
the measured quantity,

    • the measuring device used,
    • wavelength measurement band,
    • calibration of the meter to measure a certain size,
    • how to perform the measurement,
    • measurement time,
    • calculation of the result from the measured quantity.

Methods for measuring exposure to ultraviolet radiation


From the provisions contained in the standards for ultraviolet radiation measurements [PN-T-06589: 2002 Protection against optical radiation - Methods for measuring ultraviolet radiation at workstations, PN-EN 14255-1: 2010. Measurement and assessment of people's exposure to incoherent optical radiation. Part 1: Ultraviolet radiation emitted by artificial sources in the workplace] indicates that the following values ​​must be determined to assess the fate associated with this radiation:

    • effective irradiation (HS) or effective irradiance (ES) in the wavelength range of 180 ÷ 400 nm,
    • total irradiation (HUVA) or irradiance (EUVA) in the wavelength range 315 ÷ 400 nm.

The following measuring devices can be used for this purpose:

    • wideband radiometer,
    • spectroradiometer with a matrix of detectors,
    • scanning spectroradiometer,
    • dosimeter of personal protection.

Depending on the quantity being measured, the broadband radiometer can be calibrated to measure effective irradiation (HS), or effective irradiance (ES), or total irradiation (He), or irradiance (Ee). Spectroradiometers can be used to measure the spectral irradiance. However, personal protection dosimeters must be calibrated for effective irradiation (HS). Calibrating the meters for effective irradiation measurements (HS) or effective irradiance (ES) means that their spectral sensitivity must be adjusted to the relative spectral efficiency S (l). However, depending on the organ for which the hazard is being considered, individual measuring devices must be calibrated for measurements in the range of 180 ÷ 400 nm, or 315 ÷ 400 nm. In the case of devices that measure effective irradiance (ES) or irradiance (Ee), it is necessary to measure exposure time (one-off and total during the whole shift).

In practice, to perform measurements required in the standards, ultraviolet radiation parameters at workplaces the most convenient is a portable broadband radiometer with a set of measurement probes appropriately selected for the radiation range and the considered hazard. In this case, two probes may be enough: corrected for relative spectral efficiency S (l) in the range 180 ÷ 400 nm and a non-selective probe in the range 315 ÷ 400 nm. This meter enables fast measurement and direct reading of the measured value. The measuring probe should be placed at the level of the organ (eye, facial skin or hands) for which the hazard is being considered. In the case of determining the exposure of moving persons, it is necessary to take measurements at particular places of their residence.

 

Methods for measuring exposure to visible and infrared radiation
In order to assess the hazard of visible and infrared radiation, in accordance with the provisions contained in the standards [PN-T-05687: 2002 Optical radiation protection - Methods for measuring visible and infrared radiation at workplaces.
and PN-EN 14255-2: 2010. Measurement and evaluation of people's exposure to incoherent optical radiation. Part 2: Visible and infrared radiation emitted by artificial sources at the workplace], it is necessary to determine six different parameters of this radiation:

    • effective energy luminance (radiance) (LB) in the wavelength range 300 ÷ 700 nm,
    • effective irradiance (EB) in the wavelength range 300 ÷ 700 nm,
    • effective energy luminance (radiance) (LR) in the wavelength range 380 ÷ 1 400 nm (VIS and IRA),
    • effective energy luminance (radiance) (LR) in the wavelength range 780 ÷ 1 400 nm (IR-A),
    • irradiance (EIR) in the wavelength range from 780 nm to 3 000 nm,
    • irradiance (Eskóra) or irradiance (Hskóra) in the wavelength range from 380 to 3000 nm.

The following measuring devices can be used for this purpose:

    • wideband radiometer,
    • spectroradiometer with a matrix of detectors,
    • scanning spectroradiometer.

Generally, the following measurements are necessary to assess the hazard of visible and infrared radiation: effective energy luminance (radiance) calibrated to the relative spectral effectiveness of photochemical damage B (l), or calibrated to the relative spectral effectiveness of causing thermal damage R (l) and irradiance appropriate wavelength ranges.

In the case of photochemical risk assessment of the retina with blue light (in the range of 300 ÷ 700 nm), the choice of the measured parameter depends on the viewing angle of the radiation source (α). In the case of α ≥ 11 mrad angle, then the energy luminance measurement (radiance) should be measured, and when α <11 mrad - measurement of the effective irradiance intensity. In both cases, the radiometer probes must be calibrated to the relative spectral effectiveness of causing photochemical damage B (l).


The assessment of the thermal risk of the retina is performed using a radiometer whose probe will be calibrated to the relative effectiveness of the spectral triggering of thermal damage R (l). However, the choice of the measuring range (380 ÷ 1 400 nm or 780 ÷ 1 400 nm) depends on the presence of a visual stimulus. It is assumed that its limit is 10,000 cd / m2. When the luminance value is exceeded, the assessment is made in the infrared and visible radiation range.
In both cases, one should also measure the time of single exposure and the viewing angle of the radiation source (α).
The assessment of the thermal risk of the cornea and the lens of the eye and skin should be carried out using a broadband radiometer equipped with probes with constant spectral sensitivity in the wavelength range 780 ÷ 3000 nm (eye) or 380-3000 nm (skin). In both cases, one-time exposure should also be measured.


The measurement of exposure to visible and infrared radiation using a broadband radiometer is carried out analogous to that for ultraviolet radiation. The measuring probe should be placed at the level of the organ (eye, facial skin or hands) for which the hazard is being considered. In the case of determining the exposure of moving persons, it is necessary to take measurements at particular places of their residence.