Health Hazards After a Hurricane

Residents walk through flood water after Hurricane Irma.

In late September 2022, Hurricane Ian wreaked havoc throughout parts of the Caribbean, including Cayman Islands and Cuba, before reaching reaching Category 4 status as it reached the western coast of Florida. Tropical storms and hurricanes make landfall in the United States nearly every year with varying levels of damage. The effects are not just monetary; they can be measured in the loss of lives, housing, jobs, and physical and mental health problems.

As a hurricane sweeps through, the first order of business is survival. After the initial assault is over, people still face a multitude of dangers for days, weeks, months, and sometimes years. These include contaminated flood water; disease outbreaks due to tight quarters in evacuation centers or shelters; difficulty accessing medical care and filling prescriptions; mosquito-borne diseases; mold and mildew; water, gas, and electricity shortages; weakened infrastructure; and, finally, mental health effects. Lessons learned after Hurricane Katrina in 2005 and more recent storms have helped first responders, Federal Emergency Management Agency (FEMA), and local agencies better prepare for natural disasters, but when the storm clears, there are many hazards to avoid.

Contaminated Flood Waters Cause Serious Infections

Hurricane Harvey dropped anywhere from 10 to 51 inches of rain across southeast Texas and western Louisiana, causing major flooding across the region, especially in the greater metropolitan area of Houston.1 Hurricane Irma brought rainfall of up to 15 inches and storm surges of up to 10 feet to large areas of Florida.2 Parts of Georgia and South Carolina were also affected. With over 10,000 people rescued from floodwaters in Texas3 and more in other regions after Irma, who then returned to check on their property, it’s safe to say that thousands of people were exposed to the risks of contaminated floodwater.

Floodwaters are very likely to be contaminated with all kinds of things from bacteria, viruses, and parasites to sewage and chemical pollutants. Harvey hit a region of Texas filled with oil refineries and chemical plants, 50 of which were damaged during the storm. In just a few weeks, they have released “a year’s worth of pollutants.”4 The Environmental Protection Agency also reported that 40 waste treatment plants are not up and running, and there had been containment failures at many of them. The failure of these systems can result in the release of Escherichia coliSalmonella, and other bacteria into the water. When The New York Times analyzed water in two Houston neighborhoods, they discovered in one home levels of E. coli 135 times higher than what’s considered safe as well as high levels of arsenic, lead, and other heavy metals.5 In Florida, because of Irma, over 28 million gallons of sewage were released after power failures caused the electric pumps in the system of wastewater (and sewage) lift stations to stop working. Additionally, Vibrio vulnificus, a Gram-negative bacterium that is endemic to the Gulf Coast, is likely present in the floodwaters. After Hurricane Katrina, Vibrio caused the deaths of five people and 22 lost limbs.6 Contaminated flood water can cause soft tissue infections like cellulitisMRSA, and necrotizing fasciitis in individuals with open wounds or cuts. It can also cause gastrointestinal illnesses if the water is ingested, which can happen inadvertently if there is no place to properly wash hands, if food has come in contact with floodwater, or as cleanup efforts get underway. In Texas, there has already been one report of a first responder diagnosed with necrotizing fasciitis after floodwaters infected a bug bite. “Came home around 4pm and noticed a small bite on my left arm not huge but probably Nickel sized swelling,” wrote J.R. Atkins of Missouri City, Texas, in a Facebook post.7 A quick diagnosis, treatment with antibiotics, and several surgeries have helped him get on the road to recovery. Another danger of floodwater are the hidden objects and creatures that may be present. People can injure themselves as they run across objects that cannot be seen while wading through the murky water. Snakebites are also a significant hazard, as snakes try to move to higher ground. Fire ant colonies are also known to abandon their underground homes and form floating clumps that, when disturbed by a human, can turn into an aggressive attack force that delivers hundreds of stings. Mike Hixenbaugh, a medical writer for The Chronicle, stepped on a cluster of fire ants while working on a flood story in Texas after Harvey. “[Fire ants] tore my left ankle/foot up,” he reported in an email.8

Tight Quarters Lead to Outbreaks of Illness

During Harvey, over 42,000 Texans sheltered in evacuation centers. Many people are still there because their homes are gone or too damaged for habitation. In Florida, over 127,000 people9 stayed in government-run shelters during the storm and about 4,000 remained as cleanup began.10 Close quarters can lead to outbreaks of common communicable diseases like rotavirusnorovirus, and respiratory infections including influenza.

Limited Access to Medical Care

For those who require medical care for chronic conditions such as kidney diseasediabetesheart disease, and asthma, a hurricane can present a serious problem. Most hospitals have emergency plans in place but are often quickly overwhelmed with patients. Pharmacies can become inaccessible or lose inventory, leaving people without necessary prescriptions. Some people may not even be certain of the names of drugs they are taking, and medical records may be hard to access during an emergency. In Houston, one dialysis provider cares for about 6,700 patients requiring dialysis every 2 to 3 days, but only about one-third of their 100 locations were open following Harvey.11

The elderly population is particularly vulnerable after a hurricane. Over 19% of residents in Florida are 65 or older, and that figure rises to 33% in some of the hardest hit counties. Some are in nursing homes, but the recent trend toward staying at home has left many seniors, such as Monika and Vernon Maitland of Cape Coral, Florida, to fend for themselves or dependent on relatives they live with for any special care they need. “Mr. Maitland, 91, suffered a stroke last year that paralyzed half of his body, and Ms. Maitland, 70, worried he would develop painful bed sores without air conditioning to cool him down. She would have to try to keep him in a chair.”12

Mosquitoes Thrive

During hurricanes, most of the mosquito population is washed away by wind, water, and flooding. However, they usually rebound quickly, as rain and flooding leave lots of standing water in which to lay eggs, especially in areas like Houston that already had a mosquito problem. “There’s just debris everywhere. It’s like Aedes aegypti heaven,” says Dr. Peter Hotez, dean of the National School of Tropical Medicine at Houston’s Baylor College of Medicine.13 The Aedes aegypti are the mosquitoes responsible for transmitting a number of tropical illnesses including chikungunyaZika, and dengue fever. The Culiseta melanura mosquitoes are a vector for Eastern equine encephalitis, and the Culex mosquito can infect people with St. Louis encephalitis or West Nile virus. A year after Hurricane Katrina, cases of “neuroinvasive” West Nile virus (causing encephalitis and meningitis) in the affected areas more than doubled.14 Officials encourage residents to get rid of pools of water in birdbaths, potted plants, old tires, swimming pools, and toys and furniture left outside. In an effort to combat a rise in the mosquito population, Harris County, home to Houston, has sprayed over 70,000 acres, and the Air Force Reserve has used C-130 planes to fly over 2 million acres of southeastern Texas to spray a chemical that will kill mosquitoes.15

“You Can Almost Watch the Mold Grow”

“It’s a toxic place to be inside,” said Doug Stamm, 69, of Florida, referring to his ruined trailer. “You can almost watch the mold grow.”16 Mold and mildew begin to take hold in houses almost immediately after flooding. Mold can cause respiratory problems, bringing on coughing, wheezing, allergic reactions, infections, and asthma attacks. In some cases, mold can even kill. Just 2 months after Katrina, an investigation by the US Centers for Disease Control and Prevention (CDC) found that mold had grown in half of 112 homes damaged by water.17 “High 90s, super humid, it’s like a petri dish for mold,” said Frank Zeigon, an insurance claims consultant in California.18

Shortages of Water and Gasoline, Plus Power Outages

Due to flooding, many water treatment facilities may not be functioning properly in areas hit by hurricanes. This can lead to water shortages and the resulting inaccessibility of drinking water, water for cooking and cleaning, and clean water for bathing. Gasoline also comes at a premium, as gas stations wait for more fuel and some wait for flooding to clear. Being without power for a few hours or days is something most Americans have done without too much trouble, but after Harvey, Irma, and Maria, millions of people were without power, and some areas, like the entire island of Puerto Rico, are looking at outages that may last up to 6 months. Right now being without power means dealing with high temperatures without the relief of air conditioning. It also hampers people’s ability to dry out buildings damaged by flooding. Food that needs refrigeration must be thrown out. It means people must have cash on hand to buy important supplies from stores where cash registers and credit card readers are not working. People face difficulty in charging cell phones and powering important medical devices that require electricity. If they have gasoline, many people will use a generator for electricity, but that comes with its own hazards. One man in South Carolina has already died from carbon monoxide poisoning after using a generator inside his mobile home.19 Power outages also affected the Arkema chemical plant in Texas, causing huge explosions of chemicals that needed refrigeration. Also in Texas, Dow Chemical reported a lightning strike that triggered leaks and a toxic gas release, and ExxonMobile reported damage to two refineries that caused them to release pollutants.20

Flooding in a Texas neighborhood after Hurricane Harvey.

Damaged Buildings and Infrastructure

Across the Caribbean, Florida, Texas, Georgia, South Carolina, and Louisiana, thousands of homes and businesses have sustained damage. As already mentioned, mold and mildew are a concern after flooding, but so are structural problems with water treatment facilities, oil refineries, chemical plants, dams, levees, water reservoirs, and more. The full extent of damage to infrastructure like roads, culverts, and bridges may not be known for months or longer as evidenced by a bridge on the New York State Thruway that collapsed from unseen flood damage, killing 10 people.21

Mental Health Concerns

People who live through a hurricane and escape with no physical effects are still vulnerable to depression and post-traumatic stress disorder (PTSD) because of their experiences. “People get so upset when they don’t know what’s going on. It’s extraordinarily disorienting in our hyperconnected society,” says Dr. Richard Jackson, a professor at UCLA’s Fielding School of Public Health and former director of the CDC’s National Center for Environmental Health.22 Studies after Hurricane Katrina showed that 30%-50% of survivors had PTSD, and 36% of children showed serious emotional disturbances. After Hurricane Sandy, PTSD was seen in 20% of residents, while 33% reported depression and 46% said they were experiencing anxiety.23 Communities that experience a hurricane and the resulting mental anguish are likely to see an uptick in substance abuse and domestic violence.24

Preparation is Half the Battle

The effects of hurricanes are as long-lasting as they are varied, but with good preparation, the impact can be decreased. Lessons learned after every previous hurricane, especially Katrina, have helped FEMA and other agencies better prepare for future disasters. Primarily led by FEMA initiatives, several steps were taken before recent hurricanes to speed the recovery process. Paperwork needed to allow military assistance with recovery is completed in advance so mobilization is much faster. First responders have practiced disaster plans, and better training involves federal and local responders working together for a more coordinated response. Emergency supplies are pre-positioned so there is no wait for supply routes to reopen after the storm is over. Hospitals and nursing homes have evacuation and emergency plans in place and training to use them. FEMA directors are now required to have disaster management experience to avoid a repeat of Michael Brown’s mismanagement after Katrina. And the public can now be enlisted to help as they did during Harvey by rescuing neighbors and strangers with personal watercrafts.25 Not all of these preparations can stop a disaster from happening, but they do make rescue and recovery faster for those affected. “That’s probably the biggest change in recent years. The realization that disaster response is not just a government response, it is a societal response. The federal government has a role, and so does everyone else,” said William Carwile, FEMA’s associate administrator for response and recovery until his retirement in 2013.26


Originally published Oct. 5, 2017. Updated Sep. 30, 2022.


1, 3. Gallager, JJ. Hurricane Harvey wreaks historic devastation: by the numbers. ABC News website. Published September 1, 2017. Accessed September 22, 2017.

2. Amadeo, K. Hurricane Irma: facts, damage, and costs. The Balance website. Updated September 19, 2017. Accessed September 22, 2017.

4. Belluz J. Flesh-eating bacteria, cancer-causing chemicals, and mold: Harvey and Irma’s lingering health threats. Vox Published September 22, 2017. Accessed September 22, 2017.

5. Kaplan S, Healy J. Houston’s floodwaters are tainted, testing shows. The New York Times Published September 11, 2017. Accessed September 22, 2017.

6. Brodwin E. Scientists warn that floodwaters from Hurricane Harvey still pose a lingering threat – here’s what to watch out for. Business Insider Published September 12, 2017. Accessed September 22, 2017.

7. Abrams A. Hurricane Harvey First responder gets flesh-eating bacteria. Time. Published September 7, 2017. Accessed September 22, 2017.

8. Hauser C. Fire Ants Are Yet Another Hazard in Houston’s Flooded Streets. The New York Times Published August 30, 2017. Accessed September 22, 2017.

9. AP Staff. The Latest: Irma inland near Tampa, still Category 2 storm. AP News. Published September 11, 2017. Accessed September 22, 2017.

10. The Associated Press. Florida recovers, rests, reflects in wake of Hurricane Irma. The New York Times. Published September 17, 2017. Accessed September 22, 2017.

11, 17, 20. Lant K. Hurricane Harvey is over, but the public health impact is just beginning. Futurism Published September 4, 2017. Accessed September 22, 2017.

12. Bidgood J, Yee V. In Florida, a storm’s fright gives way to a blackout’s troubles. The New York Times Published September 11, 2017. Accessed September 22, 2017.

13. Fox M. Mosquitoes, medicine and mold: Texas battles post-Harvey health issues. Published September 1, 2017. Accessed September 22, 2017.

14. Kaplan S, McNeil DG. Short answers to hard questions about health threats from Hurricane Harvey. The New York Times Published August 31, 2017. Accessed September 22, 2017.

15. CBS News. Houston launches all-out assault to combat mosquitoes in wake of Harvey. CBS News. Published September 16, 2017. Accessed September 22, 2017.

16, 18. Murphy B, Cranney J. ‘He was crying and moaning in agony’: Public health crisis looms after Irma. USA Today Published September 18, 2017. Accessed September 22, 2017.

19. Roldán C. SC man running generator during Irma inside home dies from carbon monoxide poisoning. The State Published September 12, 2017. Accessed September 22, 2017.

21. Grigg NS. Flooding from Hurricane Harvey causes a host of public health concerns. Scientific American Published September 2, 2017. Accessed September 22, 2017.

22. Schumaker E. Hurricane Harvey’s public health impact extends beyond flooding. The Huffington Post Published August 31, 2017. Accessed September 22, 2017.

23. Kim H. Why Harvey will be a mental health disaster, too. Fortune Published September 6, 2017. Accessed September 22, 2017.

24. Gluck, F. Hurricane Irma’s mental health impact will linger long after the damage is repaired. Published September 17, 2017. Accessed September 22, 2017.

26, 26. Philipps D. Seven hard lessons federal responders to Harvey learned from Katrina. The New York Times Published September 7, 2017. Accessed September 22, 2017.

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