Abstract: On March 3, 1999, Employees #1 through #13 and coworkers, including cashiers, stock clerks, and a meat cutter, arrived for work at a grocery store in Lodi, CA. A contractor had been operating a power buffer that morning before the store opened. The power buffer was propane-powered, but the contractor had been using a canister of liquid propane instead of a canister of propane gas. As a result, an excessive amount of carbon monoxide had built up throughout the store. Employees began to experience symptoms such as dizziness, nausea, headache, weakness, and chest tightness. The Lodi Fire Department was called and it measured a carbon monoxide level of 160 ppm upon entering the store. The store was evacuated and Employees #1 through #13 were sent to the hospital for evaluation, then released. Factors contributing to the incident included failure of the store to monitor the air for carbon monoxide; improper use of the power buffer by the contractor; and lack of knowledge on the part of the employer of the symptoms of carbon monoxide exposure. The employer was cited for 1) failure to inspect the power buffer, even though it was a new piece of equipment brought to the work site; 2) failure to conduct carbon monoxide measurements when employees exhibited symptoms of overexposure; and 3) a missing cover plate/circuit breaker on an electrical panel.