Association of Tropical Cyclones With County-Level Mortality in the US

Study key findings & significance

• From 1988 to 2018, hurricanes and other tropical cyclones in the U.S. were associated with up to 33.4 percent higher death rates from several major causes in subsequent months.
• The largest overall increase occurred in the month of hurricanes for injuries (33.4 percent), with increases in death rates in the month after tropical cyclones for injuries (3.7 percent), infectious and parasitic diseases (1.8 percent), respiratory diseases (1.3 percent), cardiovascular diseases (1.2 percent), and neuropsychiatric conditions (1.2 percent).
• Female injury death rate increases (46.5 percent) were higher than males (27.6 percent) in the month of hurricanes. Death rate increases were higher for those aged 65 years or older in the month after tropical cyclones (6.4 percent) when compared with younger ages (2.7 percent).
• The study shows how far reaching and varied the hidden costs to life could be from climate-related disasters and climate change.

Author quotes

"Recent tropical cyclone seasons—which have yielded stronger, more active, and longer-lasting tropical cyclones than previously recorded—indicate that tropical cyclones will remain an important public health concern."

Robbie Parks, first author and post-doctoral research scientist at Columbia University Mailman School of Public Health

"In the U.S., tropical cyclones, such as hurricanes and tropical storms, have a devastating effect on society, yet a comprehensive assessment of their continuing health impacts had been lacking. Our study is a first major step in better understanding how cyclones may affect deaths,"

Marianthi-Anna Kioumourtzoglou, study co-author and assistant professor of environmental health sciences at the Columbia Mailman School of Public Health

Abstract

Importance  Tropical cyclones have a devastating effect on society, but a comprehensive assessment of their association with cause-specific mortality over multiple years of study is lacking.

Objective  To comprehensively evaluate the association of county-level tropical cyclone exposure and death rates from various causes in the US.

Design, Setting, and Participants  A retrospective observational study using a Bayesian conditional quasi-Poisson model to examine how tropical cyclones were associated with monthly death rates. Data from 33.6 million deaths in the US were collected from the National Center for Health Statistics over 31 years (1988-2018), including residents of the 1206 counties in the US that experienced at least 1 tropical cyclone during the study period.

Exposures  Tropical cyclone days per county-month, defined as number of days in a month with a sustained maximal wind speed 34 knots or greater.

Main Outcomes and Measures  Monthly cause-specific county-level death rates by 6 underlying causes of death: cancers, cardiovascular diseases, infectious and parasitic diseases, injuries, neuropsychiatric conditions, and respiratory diseases. The model yielded information about the association between each additional cyclone day per month and monthly county-level mortality compared with the same county-month in different years, up to 6 months after tropical cyclones, and how these estimated associations varied by age, sex, and social vulnerability. The unit of analysis was county-month.

Results  There were 33 619 393 deaths in total (16 691 681 females and 16 927 712 males; 8 587 033 aged 0-64 years and 25 032 360 aged 65 years or older) from the 6 causes recorded in 1206 US counties. There was a median of 2 tropical cyclone days experienced in total in included US counties. Each additional cyclone day was associated with increased death rates in the month following the cyclone for injuries (3.7% [95% credible interval {CrI}, 2.5%-4.9%]; 2.0 [95% CrI, 1.3-2.7] additional deaths per 1 000 000 for 2018 monthly age-standardized median rate [DPM]; 54.3 to 56.3 DPM), infectious and parasitic diseases (1.8% [95% CrI, 0.1%-3.6%]; 0.2 [95% CrI, 0.0-0.4] additional DPM; 11.7 to 11.9 DPM), respiratory diseases (1.3% [95% CrI, 0.2%-2.4%]; 0.6 [95% CrI, 0.1-1.1] additional DPM; 44.9 to 45.5 DPM), cardiovascular diseases (1.2% [95% CrI, 0.6%-1.7%]; 1.5 [95% CrI, 0.8-2.2] additional DPM; 129.6 to 131.1 DPM), neuropsychiatric conditions (1.2% [95% CrI, 0.1%-2.4%]; 0.6 [95% CrI, 0.1-1.2] additional DPM; 52.1 to 52.7 DPM), with no change for cancers (−0.3% [95% CrI, −0.9% to 0.3%]; −0.3 [95% CrI, −0.9 to 0.3] additional DPM; 100.4 to 100.1 DPM).

Conclusions and Relevance  Among US counties that experienced at least 1 tropical cyclone from 1988-2018, each additional cyclone day per month was associated with modestly higher death rates in the months following the cyclone for several causes of death, including injuries, infectious and parasitic diseases, cardiovascular diseases, neuropsychiatric conditions, and respiratory diseases.