If you see a low-flying helicopter over Boston this week, don’t be alarmed. It’s just testing radiation levels.

The US Department of Energy’s National Nuclear Security Administration will conduct several daytime flyovers from Tuesday through Friday to measure how much natural radiation is in the area along the Boston Marathon route, NNSA said in a statement.

NNSA will provide the information to state and local authorities, spokeswoman Shelley Laver said.