A Heatwave Can Kill You in 27 Ways

"Dying during a heatwave is like a terror movie with 27 bad endings to choose from," says Camilo Mora in a press release—and the Hawaiian researcher has detailed exactly what those 27 ways are. The 21st century has already experienced a rash of deadly heatwaves, from the more than 14,000 people who died in France in 2003 to 2,000-plus victims in India in 2015, and Mora explains that it's relatively easy to list cases of mass heat-related casualties, but answering why people died is less clear. In a paper appearing in Circulation: Cardiovascular Quality and Outcomes, Mora and his colleagues came up with 35 possibilities (by pinpointing five physiological mechanisms that can affect seven vital organs: brain, heart, intestines, kidneys, liver, lungs, pancreas), looked for heat-related medical evidence of them, and confirmed 27 of them have happened. Here are the five mechanisms, and the organ failure they can trigger:

1. Ischemia: In extreme heat, blood flow is rerouted to the skin in an attempt to cool it down, which deprives organs of needed blood flow and can cause problematic chemical compounds to form. (all but lungs)
2. Heat cytotoxicity: If your body temperature crosses a certain threshold, cells become damaged. (all but pancreas)
3. Systemic inflammatory response: Inflammatory responses can be good when it comes to, say, healing a wound as it pushes white blood cells to the skin, but inflammation can also exacerbate the leakage into the body of the contents of organs whose membranes have broken due to mechanisms 1 and 2. (all)
4. Disseminated intravascular coagulation: Proteins that cause our blood to clot can become overactive, which can cause clots that wreak havoc with the blood flow five organs (all but heart, pancreas)
5. Rhabdomyolysis: When mechanisms 1 or 2 meet with physical activity, skeletal muscle cells can break down, causing myoglobin to leak. It's toxic to the impacted organs. (kidneys, liver, lungs only)