Workplace Medical Mystery Solved: Water Patrol Deputy Gets Sick Out on the Lake

Posted on by Stephanie Stevens, MA

Jim worked as a water patrol deputy for the county sheriff’s office. While working a 10-hour shift in the hot sun over a busy holiday weekend he began to feel sick. It started with a headache while he was working in a channel where hundreds of boaters congregate for a floating party.  He then became dizzy and started to slur his speech. Jim’s patrol partner rushed him to the shore where medics took him to the hospital. Read more about his case here.

At first it seemed Jim may be suffering from heat exhaustion, however, his slurred speech indicated something more severe. While his symptoms were consistent with heat exhaustion, emergency department staff also tested a sample of Jim’s blood for carboxyhemoglobin (COHb), a marker of carbon monoxide exposure, after learning that he had been on a boat for most of the day. Test results indicated Jim was suffering from carbon monoxide poisoning with a COHb concentration of 20%.

Carboxyhemoglobin is a substance made in your blood when hemoglobin, a part of red blood cells, binds with carbon monoxide instead of oxygen. Concentrations of COHb greater than 15% can be potentially toxic. Smoking tobacco increases the amount of CO in the blood so smokers are at greater risk of CO poisoning when exposed to another source of CO, such as potentially elevated CO levels in the channel that day, which may have been caused by excessive boat traffic.

Photo by NIOSH

Jim was given 100% oxygen through a facemask placed over his nose and mouth and will make a full recovery.

Carbon monoxide is a colorless and odorless gas that can poison or kill someone who breathes too much of it. It is produced any time a fossil fuel is burned. Gasoline-powered engines on boats, including onboard generators, produce CO. Traveling at slow speeds or idling in the water can cause CO to build up in a boat’s cabin, cockpit, bridge, and aft deck, or in an open area. The most common symptoms of CO poisoning are headache, dizziness, weakness, nausea, vomiting, chest pain, and confusion. High levels of CO inhalation can cause death. If near water, such as on a boat, CO poisoning can also cause a person to pass out and fall into the water and drown.

Some steps that could be taken to reduce the health hazard for the water patrol unit employees in this fictional account include:

  • Determine what actions could be taken to reduce overall CO concentrations within an area where concentrations are found to be high, thus reducing the potential for employee over-exposure. Measures might include limiting the number of boats in certain areas or enforcing a “no idle” policy when boats are stationary.
  • Employees assigned to duty on boats should receive training about the health effects of CO, how to recognize symptoms of CO poisoning in themselves and co-workers and work-practices that can reduce exposure to vehicle and boat exhaust.
  • In areas where CO concentrations are determined to be elevated, until the CO concentrations can be reduced, employee assignments should be rotated periodically to areas where CO exposure does not occur.
  • An employee exposure monitoring program can be developed to determine patterns of overexposure for employees (i.e., are they overexposed only on warm-weather holiday weekends, or at other times or during certain job tasks) and to ensure that control measures such as assignment rotation, or reduction of CO concentrations within an area with excessive CO concentrations, are effective.
  • Employees should be encouraged to report symptoms of CO poisoning to designated health and safety personnel and should be provided with appropriate medical evaluation of symptoms.

Visit the NIOSH website for more information on how to prevent CO poisoning on boats.

Stephanie Stevens, MA, is a Health Communication Specialist in the NIOSH Office of the Director.


Workplace Medical Mysteries are fictional, however, they are loosely based on Health Hazard Evaluations (HHE) conducted by NIOSH or other reports by NIOSH and other sources, and any recommendations made herein were for the specific facility evaluated and may not be universally applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved. HHEs are publicly available at, but the names of individuals and facilities mentioned in this series have been changed to protect their identities. For more information on the NIOSH HHE program, visit



McCleery, R.E., Tapp, L., McCammon, J., Dunn, K.L. (2004); Health Hazard Evaluation Report 2002-0393-2928. Retrieved from:

Centers for Disease Control and Prevention.  (2004, April 23). Carbon Monoxide Poisonings Resulting from Open Air Exposures to Operating Motorboats — Lake Havasu City, Arizona, 2003. Morbidity and Mortality Weekly Report.  Retrieved from:

Centers for Disease Control and Prevention. (2017). Prevent Carbon Monoxide Poisoning on Your Boat.

Centers for Disease Control and Prevention. (2017). Carbon Monoxide Poisoning.

Mayo Clinic. (2018). Carbon monoxide poisoning.

Quest Diagnostics. Carboxyhemoglobin, Blood.

Posted on by Stephanie Stevens, MA

2 comments on “Workplace Medical Mystery Solved: Water Patrol Deputy Gets Sick Out on the Lake”

Comments listed below are posted by individuals not associated with CDC, unless otherwise stated. These comments do not represent the official views of CDC, and CDC does not guarantee that any information posted by individuals on this site is correct, and disclaims any liability for any loss or damage resulting from reliance on any such information. Read more about our comment policy ».

    The red herring for me was that the person was identified as a “Water Patrol Deputy.” He had better get his delinquency training! Well, as they say, “CHALK IT UP TO EXPERIENCE!” WHAT WAS HE DOING GETTING CARBON MONOXIDE POISONING UNDER ANY CIRCUMSTANCE! (How many perpetrators did it take to hold his head to the exhaust fumes and make him breath it! It must have been fifty men! You can’t TASE that many, call the SWAT team for BACKUP! Yes, treat carbon monoxide poisoning with 100% oxygen but don’t tell ME he was a Water Patrol Deputy unless you call in the SWAT TEAM!)

    Thank you for taking the time to read and comment on our Workplace Medical Mystery.

    NIOSH Workplace Medical Mysteries are designed to raise awareness of potential hazards to workers. In 2002 the NIOSH Health Hazard Evaluation Program conducted an evaluation that found excessive CO exposure and confirmed a health risk existed among employees working in a channel near crowded motorboat gatherings. The summary of that evaluation can be found here:

    For more information on CO and boating, please visit:

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Page last reviewed: August 29, 2018
Page last updated: August 29, 2018