Parts of America's radiation alert network have been out of order during Japan's nuclear crisis, raising concerns among some lawmakers about whether the system could safeguard the country in a future disaster.
Federal officials say the system of sensors has helped them to validate the impact of nuclear fallout from the overheated Fukushima reactor, and in turn alert local governments and the public. They say no dangerous levels of radiation have reached U.S. shores.
In California, home to two seaside nuclear plants located close to earthquake fault lines, federal authorities said four of the 11 stationary monitors were offline for repairs or maintenance last week. The Environmental Protection Agency said the machines operate outdoors year-round and periodically need maintenance, but did not fix them until a few days after low levels of radiation began drifting toward the mainland U.S.
About 20 monitors out of 124 nationwide were out of service earlier this week, including units in Harlingen, Tex. and Buffalo, N.Y. on Friday, according to the EPA.
Gaps in the system - as well as the delays in fixing monitors in some of Southern California's most populated areas - have helped to prompt hearings and inquiries in Washington and Sacramento.
"Because the monitoring system ... plays such a critical role in protecting the health and safety of the American people, we will examine how well our current monitoring system has performed in the aftermath of the tragic situation in Japan," said Sen. Barbara Boxer, a California Democrat who chairs the U.S. Senate Environment and Public Works Committee, which plans a hearing in the coming weeks on nuclear safety.