The number of cell phone users in Canada rose from 100,000 in 1987 to more than 24 million by the end of 2010. With their growing popularity, questions have been raised about their safety. Cell phones emit low-levels of radiofrequency (RF) energy. The RF electromagnetic energy given off by cell phones is a type of non-ionizing radiation. It is similar to the type of energy used in AM/FM radio and TV broadcast signals. Cell phones in Canada must meet regulatory requirements that limit human exposure to RF energy. Health Canada has developed guidelines for safe human exposure to Radiofrequency energy .