Femtocells and public health issues
- an overview addressing some of the health issues associated with the femtocells.
Femtocells tutorial includes:
• Technology tutorial
• Interference issues
• Network architecture
• Health issues
Also see: Cellular repeater
One of the concerns that could be a concern with the use of femtocells is that of the resultant health issues associated with the use of radio frequency radiation.
While the majority of industry thinking indicates that femtocells are not a threat to health, it is often necessary to be able to be able to understand the issues at stake so that an informed decision can be made.
Currently the standards for radio frequency radiation are set to levels that allow radio transmissions of various forms to be used, but at levels where current scientific research and thinking indicates that there are no unreasonable risks.
Femtocell power levels
The power levels used by femtocells are quite low as they are essentially a forms of low power access point used for short range communications. They provide improved coverage and capacity and use the same signal formats that are used by other cellular base stations and phones.
The power levels generated by femtocells are around 0.1 watts, i.e. 100 milliwatts. These power levels are about the same as the power levels used by ordinary wireless access points for Wi-Fi.
As the phone using the femtocell is likely to be within easy radio-range, its power levels will be reduced to only the required level needed to give reliable communications. In this way the overall level of radio signal may be reduced.
It is worth noting that radio signals typically fall by a proportion equal to 1/d^2. This means that phones held to the ear are likely to create a very much greater potential health risk.
Radio health issues research
A very large amount of research has been undertaken into discovering any links between low level radio frequency radiation and health issues. This research has been ongoing for over 50 years. If any major links had been found, then it should be a safe assumption that legislation would have been altered and the use of low power radio changed.
Much of the research that has been undertaken has been statistical in nature. Research would look at users of radio equipment and those who have a much lower level of usage, or no usage at all. The results have to be interpreted in a statistical nature, because some people who are not exposed to radiation will fall ill anyway. Therefore it is necessary to look at the illnesses that occur in the two groups of people. Even with large samples, it appears that most research projects have found little or no evidence of major health risks and therefore the health organisations have been willing to allow the current levels of radiation in and around the home.
Although no direct links to cancer have been found, it is a recognised fact that radio frequency radiation does heat up local tissue - in the same way as a microwave oven works, although the power levels for microwave ovens are much higher. As a result a phenomenon known as "hot ear" can occur when a cell phone held close to the ear is used for an extended period of time. It is therefore recommended that cellphones are not used for extended periods of the day. However, it is current thinking that in view of the 1/d^2 law where power reduces as the square of the distance, means that femtocells should not pose any form of risk.
Standards for RF radiation levels
In order that those who design radio equipment are able to design to a common agreed safe standard, femtocells are deigned to the same safety limits that are applied to all wireless equipment including mobile phones, Wi-Fi access points Bluetooth devices, etc.
These safety standards have been set by the International Commission on Non-Ionizing Radio Protection (ICNIRP) and they have been endorsed by the World Health Organisation (WHO). As a result these limits have been adopted by countries around the globe giving a common standard for virtually all countries.
If any link between radio transmissions and in this case, femtocells, then it is assumed that legislation would be altered to accommodate the new findings.
Further information on femtocell health risks
This article should not be taken as rigorous scientific evidence for the safety of femtocells. However there are a number of sites where the source information on radio signals and femtocells and health issues can be followed more closely. They include the following sites:
- ICNIRP [www.icnirp.de]
- WHO [www.who.int/peh-emf]
- GSM Association [www.gsmworld.com/health]
- Mobile Manufacturers Forum [www.mmfai.org]
- Femto Forum [www.femtoforum.org]
Although one can never be 100% totally certain there are no health issues, it is reasonably safe to assume that when used sensibly there are no femtocell health problems of any significance. Like many other wireless devices used in the home nowadays, they will be able to be used without worry or concern of any health issues.
By Ian Poole
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