Some of the significant standards applicable are listed below. Most of these directives are recommendations or guidelines. However, they indicate the scientific basis of the way UV works and provide limiting values - also information on safe use of optical radiation.
-
A recommendation was issued in 1984 by the ACGIH
(American Conference of Governmental Industrial
Hygienists) with the title: Threshold Limit Values for
Chemical Substances and Physical Agents and Bio-
logical Exposures Indices (revised at Cincinnati, 1995).
These ACGIH guidelines were taken over in all their essentials by the National Institute for Occupational Safety and Health (NIOSH), the World Health Orga- nisation (WHO) and the International Radiological Protection Association (IRPA). - IRPA/ICNIRP: Guidelines on limits of exposure to ultra- violet radiation of wavelength between 180 nm and 400 nm (1985 and 1989)
- Duchene, A.S.et al. (1991): IRPA Guidelines on protec- tion against nonionizing radiation, Pergamon Press New York
- ICNIRP (International Commission on Non-Ionizing Radiation Protection): Guidelines on limits of exposure to broadband incoherent optical Radiation (0,38µm to 3µm)(September 1997)
- IEC 608259: Compilation of maximum permissible exposure to incoherent optical radiation
- prEN 121981: Radiation onto Machinery
- dated March 2000, on radiation with photobiological effect
In summary, these guidelines indicate that effective radiation at the (180 nm) 200 nm to 400 nm wavelengths is permissible at the rate of up to 30 J/m² over a working day. For eyes, the effective radiation at the (180 nm) 200 nm to 400 nm wave- lengths should not overstep a threshold of 30 J/m² per working day, and at the wavelengths between 315 nm and 400 nm (UVA) should not exceed 10 KJ/m². These thresholds are valid only for exposure to radiation from artificial UV sources at the place of work. A total annual threshold figure should be set in order to minimise long-term harm to indoor workers. For this purpose, a figure of approx. 4000 - 6000 J/m² could be appro- priate.
The adjoining graph shows IRPA´s recommendation con- cerning maximum tolerable radiation in an 8-hour day at work, and reveals that maximum susceptibility lies around 270 nm (UVC).
back