Two employees were treated after being exposed to ammonium hydroxide Thursday at Dynamic Recycling in the town of Onalaska.
A small amount of the liquid chemical was spilled or released during the recycling process, exposing the employees to toxic fumes about 8 a.m., according to the La Crosse Fire Department, which assisted the Holmen Area Fire Department.
Employees were evacuated. One person was treated for respiratory distress and the other for evaluation.
The chemicals were removed from the building, which was ventilated.
The company said it does not accept hazardous substances, but that a small amount of ammonia escaped from a container brought to the facility. The company is investigating.
The business reopened about 10:30 a.m.