Parks' team estimates that among Medicare patients alone, tropical cyclones are associated with nearly seventeen thousand additional hospitalizations per decade in the United States. “It’s shocking, frankly,” Parks told me. He views each hurricane as a profound devastation to affected communities. “Once the water subsides, it will become a huge invisible burden,” he said. The dangers go beyond rain, flooding or wind. “They are existential,” he said. “They pull at every element of the fabric of society.”
Ten years ago, two researchers, Edward Rappaport and B. Wayne Blanchard, began measuring what they called indirect storm mortality: “Losses that, although not directly attributable to one of the physical forces of the tropical cyclone, would not be expected in the absence of the storm.” How many more people were affected than official figures suggest? “To answer these questions, we have to confront others,” the researchers wrote in a 2016 paper. How far away from the hurricane should they look? (During an evacuation, a person may die as a result of an emergency or a car accident.) How long after that? (Injuries can cause death weeks after they occur.) How far is it from the center of the hurricane? Where, when and how should they look?
Rappaport and Blanchard settled on an old-fashioned methodology: they looked through stacks of death records in the vicinity of fifty-nine hurricanes since 1963. (Looking back at Hurricane Camille, they reviewed more than a thousand death certificate records in 1969.) Ultimately, the pair identified more than fourteen hundred indirect deaths—almost as many as the total number of direct deaths reported from hurricanes. Many deaths, such as those caused by electrocution due to downed power lines, were accidental. But the largest share reflected Irimpen's findings from New Orleans. “Heart attacks and other cardiovascular events are the most common contributors to indirect mortality,” the researchers wrote. Most appear to have been caused by physical exertion, such as loading sandbags before Hurricane Wilma or bailing out water from a car during Hurricane Floyd. But during Hurricane Hugo in 1989, one man reportedly dropped dead after “seeing everything he owned completely destroyed.” Their research echoed findings from other disaster studies. Three years after the 2004 earthquake in Japan. mortality The number of heart attacks was fourteen percent higher than before the earthquake. In the two weeks following Hurricane Sandy, New Jersey reported thirty-six more strokes and one hundred twenty-five more heart attacks than normal. Many of them ended in death.
Elena Naumova, a data scientist at Tufts, was part of a team that analyzed nearly four hundred thousand Medicare hospitalizations after Katrina. They found that hospitalizations for cardiovascular disease increased sixfold and remained elevated for two months. “These are hidden consequences,” Naumova told me. “It's very difficult to link what happens months later to the hurricane… but the risks remain for a long time.” Naumova now believes the storm is similar to an outbreak, the effects of which are reflected in her data. “The health care system will continually be subject to these cascading effects,” she said. “You see one wave, and another, and another.”
When researchers want to study the spillover effects of a major event, be it a natural disaster or a pandemic, they often use the concept of excess mortality. The mortality rate does not reflect the full extent of the harm; First, they eliminate injuries and illnesses from which people recover. But they can pick up on general trends that might otherwise go unnoticed. When Hurricane Maria devastated Puerto Rico in 2017, the official death toll was sixty-four, a number that seemed small given the severity of the hurricane. Then the team from researchers surveyed more than three thousand households looking for deaths that could be linked to Maria. Based on their results, they estimated that deaths likely increased by more than sixty percent in the three months following the hurricane. If all of Puerto Rico had experienced a similar surge, the hurricane would have caused nearly five thousand additional deaths.
Rachel Young, an environmental economist at the University of California, Berkeley, told me that she read a paper about Hurricane Maria and had an idea: She might find a signal if she looked at mortality rates across the entire United States. Yang and Solomon Xiang, a colleague at Stanford, tried connection mortality data from five hundred tropical cyclones by state since 1930. “I did some testing and thought I must be doing something wrong,” she told me. “We were stunned.” Their results, published last year in Naturesuggested that the average tropical cyclone caused between seven and eleven thousand additional deaths in the fifteen years after the hurricane—three hundred times more than NOAA counted. Over the years, they have repeatedly tried to refute their findings. “We really wanted to stress test the outcome,” Young told me. They eventually concluded that severe storms were “going on much longer than we thought,” she said. “These are not just disasters of the week.”
One of the most striking discoveries in Yang and Xiang's paper hinted at How the storms caused long-term damage. Infants were affected more than any other group, and many of them died at least twenty-one months after the hurricane in question, meaning that they were not conceived at the time of landfall. This suggests that “cascades of indirect effects” rather than “direct personal effects” were lethal, Yang and Xiang wrote. Displaced people may lose access to health care, child care, and support networks; Natural disasters undermine not only physical but also mental health.
Irimpen's research at Tulane helps make sense of these cascades. In his initial study, two years after Katrina, he watched increased unemployment, lack of insurance, smoking and substance abuse, but not increases in risk factors traditionally associated with cardiovascular disease, such as diabetes or high blood pressure. However, ten years later, the number of these diseases has also increased. “We think there is a compounding effect,” he explained. Stress and negative behaviors contribute to the development of chronic diseases, which then further increase the risk of heart attacks. The consequences of the disaster were so long-lasting that it took a decade for some of these trends to emerge.
