A helicopter flying low over the Washington area on Monday was measuring naturally occurring background radiation as part of security efforts for the Jan. 20 presidential inauguration, according to the U.S. Department of Energy’s National Nuclear Security Administration.

The agency said flights in and around the District will continue, possibly until Nov. 6. Two flights are scheduled each day, and a total 20 to 25 hours are required to complete the survey.

The twin-engine Bell 412 helicopter, with radiation sensing equipment, flies in a grid-pattern as low as 150 feet, traveling about 80 mph.

The flights will allow officials to update their maps showing radiation caused by natural decay, the agency said. This survey can then be used as a baseline in case a nuclear or radiological incident occurs.

The National Nuclear Security Administration is responsible for the safety, security and effectiveness of the nation’s nuclear weapons, and responds to nuclear and radiological emergencies. The flights are being conducted by the agency’s Nuclear Emergency Support Team.

In its statement, the agency said the flights are “part of standard preparations to protect public health and safety” on the inauguration. The agency also said information from the flights “will be purely scientific in nature, and no surveillance or other form of monitoring will occur.”