SAN FRANCISCO (AP) - A low-flying helicopter is measuring naturally occurring background radiation levels in the San Francisco Bay Area.
KGO television says the testing is part of a federal research project and it begins Monday over about 69 square miles of San Francisco, Oakland and Pacifica.
The will fly a grid pattern at about 300 feet.
The survey is expected to take five days.
The information will be used to improve the way federal, state and local governments measure radiation levels.
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