Smartphone RF Exposure

I use my smartphone a lot to upload and to download video and other media files. Will that cause me to be more exposed to radiofrequency (RF) energy than when I use the phone to make a call?
A number of factors determine your exposure to RF energy when you use a mobile phone. These include the design of the phone, peak power output of the phone while it is transmitting RF energy, the duty cycle (fraction of time during a call that the phone is transmitting energy), the power level at which the phone is operating at any given moment (which is controlled by the network) and the distance of the phone to your body. The last three of these factors will vary widely, even with the same handset and the same user.

When the phone sends a large data file to the phone system, its peak power will be the same as for phone conversations, but it could be working harder (sending more data, which means a higher duty cycle of transmission) than during an ordinary voice conversation. On the other hand, you probably would not be holding the phone against your head as you might when making a phone call (which means much lower exposure to you). Smartphones can also transmit data using Bluetooth or Wi-Fi transmitters that are built into them. These typically operate at much lower power levels than the transmitter used to communicate with the phone system.

All phones on the market are tested to meet government safety limits, in the U.S. those of the Federal Communications Commission. These tests are conducted under conditions that approximate maximum exposure scenarios (phone close to the head, operating at maximum power level and duty cycle that the phone is physically capable of). Consequently in real-world usage as a phone or for data uploading or downloading, the RF exposure to the user would be lower, and probably much lower, than those measured during testing.

That said, if you are concerned about RF exposure from use of cell phones, you could reduce your exposure greatly by using a "hands free" kit that moves the handset away from your body.

Kenneth Foster, PhD
University of Pennsylvania
The information and material posted on this website is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of materials and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the website. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.