Many people use a smart phone as a working tool, they carry it with them all day long and use it to send and receive lots of emails and SMS.

When you carry your mobile phone with you all the day you are exposed to this RF Ping signal. When it is a smart phone and you use it to receive and send emails you are exposed to even more electromagnetic radiation

This video will also show you the levels or radiation emitted from a smart phone when a single email is received.