Boston — Federal officials are warning Boston-area residents they’ll be conducting aerial tests for radiation ahead of this year’s Boston Marathon.

A helicopter will be flying at low altitudes around the Massachusetts capital city from April 12 to April 15.

The U.S. Department of Energy’s National Nuclear Security Administration said officials will be measuring naturally occurring background radiation.

The measurements are meant to establish baseline levels for radiation.

The department said it’s a normal part of security and emergency preparedness and that citizens should not be alarmed.

The flyovers will occur during the day.

The 2016 Boston Marathon will be held on Monday, beginning on Main Street in Hopkinton.

Three people were killed and hundreds more were injured when two pressure cooker bombs detonated at the finish line of the April 15, 2013, marathon.

— Associated Press