Health hazard evaluation report HETA 2002-0393-2928, Lake Havasu municipal employees, Lake Havasu City, Arizona.
In August 2002, the National Institute for Occupational Safety and Health (NIOSH) was asked for assistance in evaluating carbon monoxide (CO) at the Bridgewater Channel (BC) in Lake Havasu City (LHC), Arizona. The request, from the Medical Director for Emergency Medical Services at Lake Havasu (also a physician at the Havasu Regional Medical Center), expressed concern about police and fire department personnel who patrol the BC on holiday weekends, and also about visitors in the BC who had been treated for CO poisoning in the Havasu Regional Medical Center Emergency Department (ED). These visitors had carboxyhemoglobin (COHb) concentrations greater than 30%, indicating severe poisoning. LHC Police officers (POs) and Emergency Medical Service/Firefighter (EMS/Fire) personnel patrol the waterway for as much as 10 hours per workshift on holiday weekends, when the boat traffic is excessive. In response to this request, subsequently supported by a letter from an LHC spokesperson (Chief of the Fire Department), NIOSH investigators conducted an initial investigation in the BC during the 2002 Labor Day weekend and a follow-up investigation during the 2003 Memorial Day weekend. Real-time CO monitoring was conducted on POs and EMS/Fire personnel with additional general area air sampling in and around the BC. Daily pre-shift, mid-shift, and post-shift questionnaires were administered in conjunction with exhaled breath CO measurements. Questionnaires included information on work duties and location, tobacco use, and potential CO exposure symptoms. There were 78 total workshifts where real-time CO monitoring was performed. Of those 78 workshifts, 54 exceeded the NIOSH ceiling limit of 200 parts per million (ppm), 64 exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) excursion limit of 125 ppm, 7 exceeded the Occupational Safety and Health (OSHA) Permissible Exposure Limit (PEL) of 50 ppm, 17 exceeded the NIOSH Recommended Exposure Limit (REL) of 35 ppm, and 33 exceeded the ACGIH Threshold Limit Value (TLV) of 25 ppm. Exhaled breath CO analyses and symptom questionnaires were conducted for 81 workshifts. Forty of the 81 workshifts had cross-shift COHb increases of at least 3.5%. Nonsmoking participants made up 63 of the 81 workshifts. Among the 63 nonsmoker workshifts, 42 had a post-shift %COHb at or above the ACGIH Biological Exposure Index (BEI) of 3.5%, with some levels approaching 15%. Questionnaire responses indicated that the most frequent symptom was headache, followed by fatigue or weakness, visual disturbances, and dizziness. NIOSH investigators conclude that a health hazard related to CO exposure generated from boat exhaust exists for Lake Havasu City municipal employees and visitors of Lake Havasu, Arizona. Real-time CO monitoring indicates that Lake Havasu City POs and EMS/Fire personnel working in the canal over the 2002 Labor Day weekend and the 2003 Memorial Day weekend were exposed to CO concentrations approaching and/or exceeding relevant evaluation criteria. Exhaled breath CO analyses over the 2003 Memorial Day weekend revealed estimated %COHb levels above established occupational biological exposure criteria. These elevated %COHb levels indicate employee overexposure to CO and a potential for adverse health effects. Suggested improvements for Lake Havasu municipal employees are presented in the Recommendations section of this report.