On September 30, this report was posted as an MMWR Early Release on the MMWR website (http://www.cdc.gov/mmwr).

Hurricane Katrina made landfall on August 29, 2005, on the Gulf Coast of the United States, causing loss of life, widespread property damage, and power outages. After hurricanes, some residents use portable generators and other gasoline-powered appliances for electrical power and cleanup. These devices produce carbon monoxide (CO), and improper use can cause CO poisoning (1,2). During August 29-September 24, a total of 51 cases of CO poisoning were reported by hyperbaric oxygen (HB[O.sub.2]) facilities in Alabama, Louisiana, and Mississippi. This report describes these cases and the rapidly implemented reporting system that identified them. CO poisoning can be prevented by reducing exposure to CO through appropriate placement and ventilation of gasoline-powered engines.

Investigations into CO poisonings in Florida after hurricanes in 2004 revealed that approximately 40% of patients had received HB[O.sub.2] treatment. To monitor cases of CO poisoning from HB[O.sub.2] facilities in the three affected states, CDC collaborated with the Undersea and Hyperbaric Medicine Society (UHMS) to initiate reporting after Hurricane Katrina. Members of UHMS were asked to report cases, which were compiled and submitted to CDC and shared with each affected state on a daily basis.
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HB[O.sub.2] facilities were asked to report information on individual cases and incidents in which multiple persons were poisoned by the same exposure, the date of presentation to the HB[O.sub.2] facility, state of residence, source of exposure, and the source of HB[O.sub.2] treatment. Of the 35 HB[O.sub.2] facilities (Alabama: five, Mississippi: 10, and Louisiana: 20), four (one, two, and one, respectively) reported treating patients. The extent of underreporting of treated patients is unknown.

These reports were sent daily to CDC. A case of post-hurricane CO poisoning was defined as one occurring in a patient with a clinical diagnosis of CO poisoning who had resided in a hurricane-affected state (i.e., Alabama, Louisiana, or Mississippi) and whose exposure was reported by an HB[O.sub.2] facility. Cases of CO poisoning caused by intentional exposures or fire- or smoke-related exposures were excluded.

During August 29-September 24, a total of 51 cases of CO poisoning among residents of Alabama, Louisiana, and Mississippi were reported by the HB[O.sub.2] facilities. These cases included 46 nonfatal CO poisoning cases and five deaths. Among the nonfatal cases, 16 occurred in residents of Louisiana, 24 in residents of Alabama, and six in residents of Mississippi. Among the 46 nonfatal CO poisoning cases, 37 occurred in patients who were treated with HB[O.sub.2], and nine in patients who received high flow oxygen. None of the patients treated with HB[O.sub.2] died. All five decedents were Louisiana residents. One exposure incident accounted for four of the deaths and one nonfatal case. Another incident accounted for one death and two nonfatal exposures. Two incidents each involved seven nonfatal cases. A total of 38 (74.5%) of the cases occurred within the first week after the hurricane; the other 13 (25.5%) occurred during September 6-24 (Figure).

The source of exposure for all but one of the nonfatal cases was exhaust from a portable generator. One nonfatal case was associated with use of a gasoline-powered pressure washer. The incident in which four deaths and one nonfatal CO poisoning occurred involved use of a generator in a house. The single death with two nonfatal CO poisoning cases involved use of a generator in a garage. The locations of the generators for the other cases were: under a deck (28.6%), near a window (26.2%), in a shed (16.7%), in a garage (11.9%), in a carport (9.5%), and in a basement (7.1%).

Since March 15, 2003, CDC and the American Association of Poison Control Centers (AAPCC) have collaborated to facilitate the early detection of chemical exposures of public health importance. Carbon monoxide is one of several exposures monitored. During August 29-September 24, AAPCC reported a total of 58 calls regarding CO exposure: eight in Mississippi, 21 in Mabama, and 29 in Louisiana. No deaths were reported from these exposures.