Carbon monoxide is the perfect assassin. A colorless, odorless gas emitted when fuel burns, it creeps in unannounced, causing symptoms that resemble common illnesses and killing more than 400 Americans per year.To stay safe, you’ve probably thought about installing carbon monoxide detectors in your home, especially if you have fuel-burning appliances, which range from dryers to gas stoves to water heaters. But you might not have thought to bring them on vacation, assuming instead that your lodging will have them. But in many vacation spots hotels aren’t required to have carbon monoxide detectors at all.While CO poisoning during travel is unlikely, you should take the risks seriously. In March 2025, retired Yankee player Brett Gardner’s 14-year-old son, Miller Gardner, died of carbon monoxide poisoning while on a trip to Costa Rica. A month earlier, three Americans died in a hotel room in Belize, likely due to a faulty water heater. In the United States, people have died in hotels after carbon monoxide exposure from pool heaters, ventilation systems, boilers, and blocked vents.The risk of dying of CO poisoning while traveling is low compared with, say, the risk of dying in a car accident. But one study suggests that more than 150 CO-related incidents occur in short-term lodging (including hotels and motels) in the US each year and that that number is likely underreported. And that number doesn’t include vacation rentals such as Airbnbs, other travel-related situations, or international incidents.Even if carbon monoxide poisoning doesn’t result in death, it can still cause lasting health issues. When carbon monoxide replaces oxygen in the bloodstream, it can cause long-term neurological problems — from personality changes to intellectual impairment — even if you appear to have only mild or moderate symptoms up front. And while the risks are higher for children, older adults, and those who are pregnant, people of any age and health status are at risk.But there’s some good news: CO poisoning is pretty preventable if you have a good-quality carbon monoxide detector. When you’re on the road, a small, lightweight, battery-operated detector could save your life.