This report is an updated version of the report 99-0001 that was written in January 1999. It gives a practical interpretation of the National Radiation Protection Board (NRPB) statement on restrictions on human exposure to static and time varying electromagnetic fields (EMF) and radiation, and includes a section on NRPB-R301 1998. In addition to this update is a new section on hazards to flammable atmospheres. The report is presented in three main sections covering the following topics: a review on the NRPB's guidelines of 1993 and also the 1998 ICNIRP guidelines of major factors that govern the coupling and absorption of EM energy into the human body, the information required by the site surveyor in order to make the initial calculations and comparison of the measured EMF parameters with the investigation levels, to name a few proposals for the procedures required to perform the site survey and the fuller assessment if the investigation or the reference levels have been changed. Two other effects of radio frequency radiation are discussed - ignition of flammable atmospheres and initiation of electro-explosive devices.