Flooding May Be the Climate Health Hazard of Our Time, Report Suggests

Floods are emerging as a major health hazard with inequitable global effects — both short and long term — as climate change alters weather patterns.

Flooding is the most common climate hazard, affecting more than 1.65 billion people from 2000 to 2019, with approximately 104,614 lives lost, reported Yuming Guo, MD, PhD, and Shanshan Li, MD, PhD, both of Monash University in Melbourne, Australia, and colleagues, in a special report in the New England Journal of Medicine.

They said that floods are becoming more common based on an increased average number of flood days in most countries during the period of 2001-2021 compared with 1985-2000. Projections based on high greenhouse-gas emissions have estimated that floods will increase significantly from 2071 to 2100.

“Research on the health impacts of floods remains limited, often focusing narrowly on immediate concerns, such as physical injuries,” Guo wrote in an email to MedPage Today. “The long-term health consequences, including impacts on respiratory and cardiovascular systems as well as mental health, are frequently overlooked.”

In their report, the authors detailed the health risks associated with floods. Deaths can increase, not only from flood-related accidents, but also from interrupted access to care, water and sanitation problems, waterborne pathogens, food insecurity, under-nutrition, and psychological distress.

Injuries are also a risk during and after flooding, from collisions with fast-moving objects to releases of hazardous chemicals stored in the flooded environment. Waterborne, rodent-borne, or mosquito-borne diseases, including leptospirosis, can also increase after floods, and problems with water systems can spread gastrointestinal diseases, hepatitis A and E, and other pathogens from contaminated soil or overflow of bodies of water. Overcrowding of shelters can increase transmission of respiratory diseases, and being exposed to flood water can increase infections.

Management of noncommunicable diseases can also suffer after floods, because of displacement, disruption to travel, damaged facilities, and loss of staff, records, or supplies. Prioritization of patients in flooded areas can lead to a loss of services in other areas. Pregnant women are particularly vulnerable to health harms, and children in low- and middle-income countries may be at risk for under-nutrition because of loss of resources that lead to food insecurity.

In addition, people affected by physical and economic insecurity that occurs with flooding are more likely to have depression, anxiety, and post-traumatic stress disorder. Domestic violence and psychosocial symptoms like pain can rise. This kind of stress, along with decreased school attendance and other disruptions, can affect children in particular, who may see impairments in cognitive development.

Healthcare professionals may have an important role to play in managing the health impacts of flooding. According to Guo, physicians should:

• “Educate patients about the health risks of floods and preventive measures”
• “Ensure that at-risk individuals have up-to-date medical supplies and plans for continuity of care during disasters”
• “Collaborate with public health authorities to address systemic issues, such as improving sanitation in flood-prone areas and advocating for resilient healthcare systems”

After floods, clinicians should screen for diseases in affected populations, monitor patients for mental health issues, refer them to services, and engage in community outreach related to recovery and long-term health effects.

Mary A. Fox, PhD, MPH, of the Johns Hopkins Bloomberg School of Public Health in Baltimore, who was not involved in the report, told MedPage Today that “providers are very well-respected communicators, and so when the provider is talking about being prepared for floods or whatever type of hazard may appear in their locality, they can help people be prepared.” She also emphasized the role of public health in collaboration with private health systems.

Fox noted that physicians can help advocate for multi-hazard early warning systems, and take note of climate-related hazards that affect their patients. “Healthcare providers, when they’re interacting with patients and in the electronic health record, they could start documenting, potentially, some specific connections between something like floods or other extreme event morbidity that they’re seeing,” she said.

Flooding, like other climate-related risks, disproportionately affects infants, children, older adults, and those with pre-existing health conditions. Lower-income countries and poor urban areas may have less resilient infrastructure and healthcare resources.

Within the U.S., economically disadvantaged populations and people of color are more likely to live in flood-prone areas, and to have negative health outcomes after floods because of racialized health disparities, and disinvestment in housing, education, healthcare, and food.

Lara J. Cushing, PhD, MPH, of the UCLA Fielding School of Public Health, who was also not involved in the report, told MedPage Today that her research has found that hazardous substances are concentrated in industrial areas in the U.S., often on coasts prone to flooding and their surrounding communities.

“Low-income communities and communities of color are more likely to live near an at-risk site, which speaks to the inequitable public health burden that climate change causes, and flooding causes,” Cushing said.

Rural communities that rely on domestic wells, she noted, “are at increased risk of contamination threats in general, but also running dry during drought, because they tend to be shallower than agricultural wells, and they’re totally unregulated.”

Cushing said that the concept of “underbounding,” in which cities have excluded surrounding unincorporated areas and communities of color from city boundaries, effectively cutting them off from water and wastewater services, means that their infrastructure may be vulnerable to effects of flooding.

She pointed out that the bipartisan infrastructure deal passed by the Biden-Harris administration was significant for its allocation of water infrastructure funding, “but the scale of the problem, both in terms of climate change and long-term deferred maintenance or neglect of our infrastructure also means it’s probably not enough, nowhere near enough.”

Cushing said because these systemic problems may not be solved in individual clinics or institutions, “to the extent that clinicians feel comfortable speaking out about the importance and the dangers of climate change and flooding, and the need for investment in climate resilience, that’s going to have the greatest impact in terms of preventing illness and injury.”