Abstract: On December 7, 2000, the Cincinnati OSHA Office heard through the media and through police reports that two fatalities had occurred at a nursing home in Bellbrook, Ohio. An OSHA compliance officer was sent up to the site to begin to determine what had gone wrong, whether or not there was occupational exposure to a hazard, and if OSHA should play a lead, supporting or no role in investigating this tragedy. The conclusion was reached that OSHA should not play a lead role in this investigation because the exposures and the deaths occurred only to patients, not to employees, of the nursing home. This determination was made as FDA was actively investigating the incident and taking a lead role in performing an investigation. The nursing home routinely ordered and received large compressed gas cylinders, or tanks, containing pure oxygen, for consumption by some of their residents, such as emphysema patients, who have unhealthy respiratory systems. Their supplier, BOC Gases, mistakenly delivered one tank of pure nitrogen in addition to the three tanks of pure oxygen which had been ordered. An employee at the nursing home hooked up this tank, which contained pure nitrogen, to the nursing home's oxygen delivery system. On December 7, 2000, this event caused two nursing home residents to die, and three additional nursing home residents were admitted to hospitals in critical condition. Within the following month, two of these three additional residents also died, bringing the total death toll to four.