Hospital construction materials: poor shielding capacity with respect to signals transmitted by mobile telephones

Electromagnetic interference (EMI) with electronic medical equipment by the handsets of mobile telephones is a well documented problem in hospitals. To gain information about how to build an EMI-free hospital and how to make rooms safe for mobile telephone handset use in the hospital building the authors measured the shielding capacities of a concrete wall, concrete blocks, a steel door, and steel-surfaced partition panels. The shielding capacities of these materials were 2-7 dB for the concrete wall, 6-8 dB for the concrete blocks, 19-27 dB for the steel door, and 20-37 dB for the steel-surfaced partition panels. These results indicate that care should be taken to shield electronic equipment from signals coming from neighboring rooms and from those under and above any patient room in which such equipment is in use. Electricity-conductive paint, electricity-conductive wallpaper, and electricity-conductive cloth are examples of inexpensive materials that can increase shielding capacity.