Abstract: The supervisor for the night crew at Houston Industrial Services wanted more workers to help speed up a tank cleaning job. The company had depleted the local supplier's stock of appropriate respirators. Additional respirators were ordered from the Houston location. Because it was the weekend and after hours, the order was made through an on-call person. After confirmation with the on-site supervisor, the order was shipped to the work site. Upon arrival, the respirators were issued to the employees and they entered the tank to commence the cleanup. After approximately two hours, around 2:30 a.m., Employees #1 through #13 began to get sick. One employee suffered a seizure. EMTs were called but all employees refused treatment. The work site was closed down and all employees were sent home. Between 5:30 a.m. and 9:00 a.m., employees arrived at Dansforth Hospital in Texas City, TX, for treatment. Thirteen employees were treated: eleven were admitted, and two were released. It was determined by the CPSI supervisor that the respirators issued to the night crew were high efficiency filters instead of organic vapor cartridges. According to CPSI, the tank contained wash water that had been used to clean a barge containing #6 oil. Analysis of the sludge found it contained benzene, toluene, styrene, and xylene as major components.