Understanding Radio Frequency (RF)

As PG&E upgrades to SmartMeter™ gas and electric meters, some customers have asked about potential health effects related to radio frequency (RF) emissions from the meters. We hope this information will help answer those questions.

We understand that our customers want to be well informed about new technologies. Electric SmartMeters™ are digital meters that have been widely used since the 1980s. The new development is a small 1-watt radio that allows two-way communication between the customer and PG&E, which enables the customer to review their daily energy use.

A SmartMeter™ transmits relatively weak radio signals, resembling those of many other products most people use every day, like cell phones, baby monitors and microwave ovens. A major radio station, by contrast, usually transmits with 50,000 times as much power.

Common household products that utilize RF

Household Products

SmartMeter™ RF and Health

In January, 2011, the California Council on Science and Technology (CCST) released a preliminary study entitled "Health Impacts of Radio Frequency from Smart Meters".

Quoting from the study, there are two primary conclusions:
  1. The FCC standard provides a currently accepted factor of safety against known thermally induced health impacts of smart meters and other electronic devices in the same range of RF emissions. Exposure levels from smart meters are well below the thresholds for such effects.
  2. There is no evidence that additional standards are needed to protect the public from smart meters.
On March 31, 2011, the final version of "Health Impacts of Radio Frequency Exposure from Smart Meters" was released by the CCST. This version incorporates public comment; however the two primary conclusions above have not changed.

SmartMeter™ devices and FCC Limits

Based on years of studying whether radio waves cause health effects, the Federal Communications Commission (FCC) has adopted Maximum Permissible Exposure (MPE) limits for radio transmitters of all types, including SmartMeters™. It includes a prudent margin of safety just in case some health effects are too subtle to have been detected. Even so, SmartMeters™ operate far below the limit—typically only about one-seventieth as much.

Exposure is based on the transmitter's power and your distance from the source. In general, doubling your distance cuts the "power density" by a factor of four. That's a major reason why radio waves from a SmartMeter™, at a distance of 10 feet, are only about one one-thousandth as much as a typical cell phone. That's also why powerful but distant radio and TV transmitters are not seen as posing any danger.

Some people have expressed concern that the long-term use of devices like cell phones might have unexpected health effects even if daily exposure is low. The World Health Organization (WHO) advises: "A large number of studies have been performed over the last two decades to assess whether mobile phones pose a potential health risk. To date, no adverse health effects have been established for mobile phone use." And cell phones are typically held against your head when in use, while SmartMeters™ are outside your house, on the other side of the wall.

Should you be concerned about long-term exposure to smart meters if scientists haven't established health problems from cell phones? Consider that SmartMeters™ transmit only about 45 seconds a day (see Field Study Update in right-side panel). You'd have to have one of our meters on your home or business for more than 1,000 years to get as much exposure to radio waves as a typical cell phone user gets in just one month.

Comparison of RF Power Density in the Everyday Environment

Power Density in Microwatts per square centimeter (µW/cm2)
Adjacent to a gas SmartMeter™ (1 foot) 0.00166
Adjacent to an electric SmartMeter™ (10 feet) 0.1
Adjacent to an electric SmartMeter™ (1 foot) 8.8
Microwave oven nearby (1 meter) 10
Wi-Fi wireless routers, laptop computers, cyber cafes, etc., maximum (~1 meter for laptops, 2 - 5 meters for access points) 10 - 20
Cell phones (at head) 30 - 10,000
Walkie-Talkies (at head) 500 - 42,000
 

Field Study Update

  • In response to the California Public Utilities Commission's request for more information about the radio frequency from SmartMeters™, PG&E submitted on November 1, 2011, a public filing that contained detailed data from a field study of 88,000 SmartMeters™. That field study, performed by PG&E's wireless network provider, Silver Spring Networks, showed that a typical SmartMeter™ communicates intermittently throughout the day for a total cumulative period of approximately 45 seconds per 24-hour period (half of the tested meters transmitting for less than 45 seconds, and the other half transmitting for more). In the study, a small number of SmartMeters™ in the outer range of the population communicated somewhat longer than 45 seconds-per-day, which resulted in an overall mean duration of approximately 62 seconds-per-day. In addition, that detailed data reflected power densities of 0.35µW/cm² (0.058% of FCC limit) for electric SmartMeters™, 0.01µW/cm² (0.0033% of FCC limit) for standard gas SmartMeters™, and 0.059µW/cm² (0.02% of FCC limit) for extended-range gas SmartMeters™.

Additional RF Resources