The diffusion of wireless technology has caused concerns about interference in the hospital environment. Most hospitals have banned the use of cell phones on their premises although wireless technology can help in delivering time critical help to patients. We discuss some factors of radio frequency (RF) near field interference. These phenomena do not lend themselves easily to theoretical evaluation. It is possible to avert medical equipment interference by performing ad hoc tests. The method requires measurements of electromagnetic fields and the observation of interference events with increasing distance between equipment and RF transmitters. The results are applicable only to the specific testing environment. The ad hoc proposed method can be found in the draft document C63.18 of the American National Standard Institute.