Study reveals thousands of long-term deaths from hurricanes

• Until recently, most of the attention has been focused on direct causes of death, such as drownings from floodwaters, rather than the complex cascade of events that can elevate mortality long after a storm fizzles.

Zoom in: The new research, published in the journal Nature, shows many higher excess deaths from the social and economic upheaval left in the wake of tropical cyclones in the U.S. than expected, coauthor Solomon Hsiang of Stanford University told Axios.

• In fact, the study shows that tropical cyclones account for roughly 3.2% to 5.1% of all deaths annually in the Lower 48 states, or about 55,280 to 88,080 excess deaths.

The intrigue: The lack of research on indirect deaths long after storms hit — often from stress that worsens cancer, heart disease and other chronic conditions — has hidden the full health burden of these storms, as well as the extent to which this accounts for broad-scale patterns of mortality, Hsiang said.

• He noted that those impacts can also arise from a series of events traced back to storms, such as costly home repairs that forces people to dip into their savings, thus reducing their ability to spend on health care.
• "Maybe, like, five or seven years later, they're faced with some sort of health challenge that's expensive, and when they look at their resources, they have fewer retirement savings than they would have otherwise had, and that leads them to make some sort of different health care choice that can have implications," he said.
• In addition, public budgets can diminish as tax revenue declines after a storm, reducing health care resources.

Between the lines: The study includes all 501 tropical cyclones that affected the continental U.S. coastline between 1930 and 2015. It estimates changes in monthly state mortality rates from 1950-2015 for the 20 years after each storm hit the country.

• The researchers used maximum surface wind speeds experienced at locations during each storm as a proxy for storm intensity, which might miss some impacts from inland flooding rains.
• The econometric model used accounts for state health care policy and geographical differences, among other factors that can influence mortality rates from tropical storms and hurricanes.
• It shows "no evidence" that storms several decades ago caused more or less of an impact than storms do today, which casts doubt on the effectiveness of better preparedness ahead of a storm and adaptation measures like improved building codes.

By the numbers: Whereas NOAA reported that the 501 storms studied caused an average of 24 direct deaths, the paper estimates that the average tropical storm or hurricane "indirectly accelerated the death" of about 7,170 to 11,430 people.

• The study finds that infants are the most vulnerable group based on risk, and that 99% of infant deaths occur more than 21 months after the storm hits.

• This points to potential indirect effects of a storm being a key factor in those deaths, since the infants were not born prior to the storm making landfall.
• In addition to infants, other demographics found to be especially vulnerable in the years following disasters included people under age 45 and African-Americans.

The big picture: States that are frequently impacted by tropical cyclones tend to have less vulnerability, measured in indirect deaths following a storm, compared to those that get hit on a less frequent basis.

• Southeastern states have the highest proportion of deaths attributable to tropical cyclones, including 13% of deaths in Florida, and 11% of deaths in North Carolina.
• During the study period, tropical cyclones contributed to more deaths in the U.S. — 3.6 to 5.2 million — than motor vehicles accidents and infectious diseases.
• Hsiang and his coauthor initially thought their results were wrong. "This was challenging for us to absorb, like ourselves, because we were so surprised by the result," he said.

What they're saying: "The study successfully highlights how the impacts on youngest ages is previously widely unreported and should have special attention paid to it," Robbie Parks, an environmental health professor at Columbia University, told Axios. Parks wasn't involved in the new study.

• As for recent and upcoming storms, including Helene, Parks said the study shows, "We need long-term recovery planning by allocating resources equitably."

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