The Washington State Department of Health has a helicopter flying very low over the Puget Sound region for the next two weeks, measuring normal background radiation levels. That helicopter is now flying over Greenwood, Phinney Ridge and Ballard today.
The helicopter flying near 8th Avenue NW about 11 a.m. Tuesday.
The helicopter will fly a grid pattern at an altitude of about 300 feet.
The measurements will be used to determine what normal radiation levels are at various locations. The data will provide a baseline that can be used for comparison should there ever be a nuclear accident, the Department of Health said.