Protecting Workers from Ultraviolet Radiation - icnirp

8. Exposure Assessment
8.1 Introduction
Protecting Workers from Ultraviolet Radiation
The measurement or monitoring of UVR from artificial sources or from sunlight may be required
for assessment of the worker’s exposure. There is a range of instruments of varying
sophistication available and the choice of a particular instrument will depend upon the accuracy
and/or ease to which measurements are required. National networks to measure the solar UVR
have been established and some provide data to the public in the form of the Global Solar UV
Index (UVI) on a daily basis. Knowledge of the UVI can help to choose the level of protective
measures for outdoor workers. For example certain protective measures such as hats may be
keyed to UVI values above 5 in some locations.
Measurements are not always required when source information or calculations are sufficient for
providing the basis for exposure evaluation. A number of approaches have been developed. For
example, UV sources can be grouped into different risk categories (as provided by the
manufacturer), such as those developed by the CIE for lamp risk groups (CIE 2002), and
protective measures (engineering and/or personal protective measures) would be keyed to the
risk group. An “exempt” category of sources would require no further hazard assessment or
protective measures, and the protective measures for Risk-Group 1 would only be necessary for
prolonged exposures. A number of publications provide typical UV emission characteristics of
commercial UVR sources (McKinley et al 1988, Sliney and Wolbarsht 1980). Detailed
measurements would then only be required when the exposure is at or near exposure limits. If the
exposure is clearly very low and well below limits, no action would be required. If the source of
UVR can be encapsulated (shielded) so that no exposure occurs outside the encapsulation or
shielding, an exposure assessment is also not needed. If the exposures are clearly far above the
occupational exposure limits, as in many welding operations, strict protective measures will be
required. In this case, an exact determination of exposure may not be required for the welder or
an associate (helper) when properly protected; however, measurements may be necessary for
other unprotected persons further away from the source.
8.2 Measurement Aims
Measurements are most likely to be of value when assessing indoor exposures to UV sources
where the characteristics of the sources are generally fixed and work practices are repetitive. On
the other hand, the constantly changing position of the sun with time of day and season and
changing meteorological conditions limits the usefulness of site-specific measurements for
predictive risk assessment in most outdoor occupations. However, they may be used to
demonstrate current exposure conditions to workers and the need for protection.
Examples of need for measurements are as follows:
8.2.1 Measurement of indoor workers´ exposure
If a worker is exposed to potentially hazardous levels of UVR at the workplace, adequate
protective measures are necessary. There may be a value in characterizing the exposure level
through calculations or measurements. The measurement result is compared with the exposure
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