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Pay close attention to the signal bars on the display panel of your cell phone. Fewer bars indicate a weaker signal. A weaker signal means the cell phone will generate more power to maintain the connection. In fact, for each bar lost due to poor signal strength the cell phone will increase its power by 1000% to maintain the connection. More power means greater exposure to the radiation for the caller. Ideally, always try to talk outdoors in an open space. This allows an easier connection from your cell phone to the nearest cell phone tower. The easier the connection the less power is needed to stay connected. Also, avoid making cell phone calls from cars, buses, trains, subways or airplanes. These enclosures make the connection more difficult and also tend to concentrate the radiation within the enclosure.

http://emfnews.org/Lifewave-Cellphone-Matrix-Shield-Test.html