A helicopter equipped with radiation-sensing technology will make several low passes over the Boston Marathon route later this week to measure naturally occurring background radiation ahead of the 122nd Boston Marathon next week.
Between Thursday and Sunday, the National Nuclear Security Administration will use the chopper to measure background radiation along the 26.2-mile marathon route and slightly beyond, flying a twin-engine Bell 412 helicopter in a grid pattern at about 150 feet above the ground at speeds of about 80 miles per hour, the agency said.
The NNSA said measuring baseline levels of radiation is "a normal part of security and emergency preparedness for major public events" and that it notifies the public in advance of the monitoring flights "so that citizens who see the low-flying aircraft are not alarmed."
According to the United States Government Accountability Office, "the surveys can be used to compare changes in radiation levels to (1) help detect radiological threats in U.S. cities more quickly and (2) measure contamination levels after a radiological attack to assist in and reduce the costs of cleanup efforts."
The NNSA has conducted a radiation survey in the Boston area before the Boston Marathon each of the last four years.
Five years ago, terrorists detonated two pressure cooker bombs near the marathon finish line, killing three people and injuring more than 260 spectators.
The helicopter is operated by the Remote Sensing Laboratory Aerial Measuring System from Joint Base Andrews in Maryland, the NNSA said.