As of 2021, the estimated number of mobile phones in use in the UK is 80 million. The number of base stations has also increased in line with the increase in the number of mobile phones and is estimated to be between 50,000 to 60,000.
Mobile Phones
Mobile phones emit power up to around ¼ watt and are typically held with their antenna 2 cm away from the user's head. The tissue nearest to the antenna is mainly exposed, and the exposure level is measured as the Specific Absorption Rate (SAR) of energy in the head. Guidelines suggest that the average SAR over any 10 grams of tissue and a 6-minute period should not exceed 2 W/kg. All phones sold in the UK must be tested to ensure they have SAR values below this limit. The SAR values for specific phone models can be found on the MMF website, with values ranging up to 1.5 W/kg.
Base Stations
Base Stations emit powers up to 100 watts. The antennas are usually positioned a few tens of meters away from the public. Despite being more widespread, the exposure is much lower compared to holding a phone. The power density of radio waves incident on the body is used to measure whole-body exposure. International guidelines advise reference levels of 4.5 or 9 watts per square meter based on frequency. Network operators comply with these international guidelines in addition to meeting UK safety laws. Publicly accessible locations experience exposures thousands of times lower than the guidelines.
