Patients in hospitals can be exposed to electromagnetic fields and optical radiation. This exposure may be higher than the limits for the general population or for workers. Such exposure may be associated with risks, which have to be weighed against the medical necessity and against the risks of using alternative methods.


Electric, magnetic and electromagnetic fields (EMF) with frequencies between 0 and 300 gigahertz can be used in hospitals for diagnostic or therapeutic purposes. The most important diagnostic application of EMF is magnetic resonance imaging (MRI), which uses static magnetic, low frequency and radiofrequency EMF. Established therapeutic applications of EMF include transcranial magnetic stimulation and diathermy. Fields with frequencies between between 300 gigahertz and 3 x 1015 hertz are usually called optical radiation. This frequency band incorporates infrared radiation, visible light and ultraviolet radiation. Lasers emit optical radiation of one frequency with high power in a small surface area. Because of its relatively low penetration depth, optical radiation is mostly used for imaging microscopic structures of superficial tissue layers such as the skin or the gut wall. Therapeutic applications of optical radiation include lasers for surgery and ablation and ultraviolet irradiation for skin disorders.

Possible sensory and health effects of strong static magnetic fields and low frequency EMF are vertigo, nausea and nerve stimulation. A possible health effects of strong radiofrequency EMF and optical radiation is heat-related damage, in particular to the eyes. Strong UV-radiation can also increase the risk of skin cancer. Health care workers in the Netherlands are protected against the risks of EMF and optical radiation by the implementation of European directives 20013/35/EU and 2006/25/EC in the working conditions decree (in Dutch). Although the exposure of patients may exceed the limits for the general population or for workers, the physician has to weigh the potential health risks against the benefits of diagnosis or treatment. EMF, infrared radiation and visible light do not cause DNA-damage, in contrast to ionising radiation used in X-rays or computed tomography (CT). However, because different diagnostic techniques give different information about the body's interior, the ultimate choice also depends on the diagnostic aim.

Summary of RIVM activities

RIVM performs research and advises government departments about the risks of EMF and optical radiation in hospitals. In the context of the revision of the European EMF directive, RIVM has analysed MRI working practice  in the Netherlands and literature data on EMF exposure of hospital workers. Various protection systems for MRI workers were also compared. RIVM has conducted two horizon scans, in 2011 and 2014, to summarise recent developments in medical techniques involving EMF and optical radiation that could influence the exposure of patients and health care workers. Examples of new diagnostic techniques involving EMF and optical radiation include microwave tomography, terahertz imaging, optical coherence tomography, photoacoustic tomography, laser speckle imaging and optical endomicroscopy. Examples of new therapeutic techniques involving EMF and optical radiation include hyperthermia with nanoparticles, pulsed or fractional laser treatment and endoscopic laser surgery. EMF can also be used to store or transfer information from measurement devices in or on patients.

RIVM has participated in working groups of the International Commission for Non-Ionizing Radiation Protection (ICNIRP)  on general radiation protection principles, medical diagnostic exposure and cosmetic exposure to EMF and optical radiation. RIVM also contributes to the activities of the Health Council of the Netherlands  and the New and Emerging Technologies Working Group of the European Commission. RIVM occasionally contributes to ad hoc risk assessment projects such as the Environmental Health Criteria of the World Health Organization and the report on Health Canada's radiofrequency exposure limits  of the Royal Society of Canada (2013).

Areas of expertise

Medical EMF exposure; medical exposure to optical radiation; occupational EMF exposure; epidemiology.

[updated: 23 August 2022]

  • Karipidis, K., Abramowicz, J., d’Inzeo, G., Green, A.C., Miller, S., Okuno, T,. Stam, R., Toivo, T., Croft, R. Feychting, M., Hirata, A., Marino, C., Oftedal, G., van Rongen, E., Röösli, M., Sienkiewicz, Z., Watanabe, S. (2020) ICNIRP Statement on intended human exposure to non-ionizing radiation for cosmetic purposes. Health Physics 118, 562-579.
  • Stam R, Yamaguchi-Sekino S. (2018) Occupational exposure to electromagnetic fields from medical sources. Industrial Health 56, 96-105.
  • Green, A.C., Coggon, D., de Sèze, R., Gowland, P. A., Marino, C., Peralta, A. P., Söderberg, P. G., Stam, R., Ziskin, M. C., van Rongen, E., Feychting, M., Asmuss, M.,  Croft, R., D'Inzeo, D., Hirata, A., Miller, S., Oftedal, G., Okuno, T., Röösli, M., Sienkiewicz, Z. & Watanabe, S. (2017) ICNIRP statement on diagnostic devices using  non-ionizing radiation: Existing regulations and potential health risks. Health Physics, 112, 305-321.
  • Demers, P., R. Findlay, K.R. Foster, B. Kolb, J. Moulder, A. Nicol, F., Stam R. (2014) A review of Safety Code 6 (2013): Health Canada’s safety limits for exposure to radiofrequency fields. Royal Society of Canada, Ottawa. 
  • Ministry for Social Affairs and Employment (2008) Using MRI safely. Practical rules for employees.  Ministry for Social Affairs and Employment, The Hague. 
  • Stam, R. (2014) The revised electromagnetic fields directive and worker exposure in environments with high magnetic flux densities. Ann Occup Hyg, 58, 529-41.
  • Van Rhoon, G. C., Aleman, A., Kelfkens, G., Kromhout, H., Van Leeuwen, F. E., Savelkoul, H. F. J., Wadman, W. J., Van De Weerdt, R. D. H. J., Zwamborn, A. P. M. & Van Rongen, E. (2011) Health Council of the Netherlands: No need to change from SAR to time-temperature relation in electromagnetic fields exposure limits. International Journal of Hyperthermia, 27, 399-404.

These publications are specific to EMF and optical radiation in hospitals. For publications on other topics see links to 'Electromagnetic fields at work' and 'Electromagetic fields in daily life' in the left column.