-North Dakota's Health Department said it's surveying air quality near the site of a fire at an industrial park in Williston, the heart of the state's oil patch.
Chemicals used in hydraulic fracturing caught fire at an industrial warehouse in Williston. Officials said they're going to let the fire burn out on its own because pouring water on the blaze would create a secondary problem for nearby waterways.
The North Dakota Department of Health said it's monitoring air quality around the industrial park for any threats to public health.
"The fire in the industrial park has resulted in a plume of smoke that may adversely affect air quality in the surrounding area, and may cause health concerns," it said in a statement Tuesday.