Not once, but twice over the past month, employees at the Buckeye Mill in Perry, Florida, have been subjected to releases of toxic chlorine dioxide into the air. According to WCTV, on both May 22 and May 28, the harmful chemical was released from the plant, which is owned by Koch Industries subsidiary Georgia Pacific.

Exposure to chlorine dioxide, primarily used to bleach wood pulp, is limited by the Occupational Safety and Health Administration, which describes the chemical as a “severe respiratory and eye irritant.” Reportedly, workers were evacuated from the Buckeye plant after the release of what witnesses described as a big green cloud, and while there were no injuries reported, these incidents highlight the risk inherent in the operation of these and other plants that use the toxic chemical.

Groups like U.S. PIRG have highlighted that safer alternatives exist to using chlorine dioxide to bleach paper, yet, according to PIRG, multiple Koch Industries owned Georgia Pacific plants continue to use and stockpile the chemical, endangering hundreds of thousands of people who live near the facilities. According to a report from Greenpeace, Koch Industries has consistently gone to bat against efforts to secure chemical facilities from terrorist attacks, in addition to advocating against other basic environmental protections.

Why rent a plane to write your name in the sky, when you can leave toxic green clouds in your wake?