```

Flooding and Respiratory Health: Long-Term Effects and Prevention

Heavy rains and sea level rise contribute to major flooding events that are one effect of climate change. Surging water rushing into buildings often causes immediate harms—such as drowning deaths, injuries while seeking shelter or fleeing, and hypothermia after exposure to cold waters with no shelter or heat—but long after news trucks leave and public attention moves on, flooding continues to affect communities in visible and less visible ways. Among the less visible threats is a higher risk of respiratory health problems like asthma and allergic reactions.

Contaminants and Airborne Dust

Floodwater may carry toxic chemicals, heavy metals, pesticides, biotoxins, sewage, and water-borne pathogens into buildings. After floodwaters recede, some toxic contaminants remain in dried sediments left behind. Everyday actions like walking and cleaning can disturb this sediment, turning it into microscopic airborne dust. Anything in that dried flood sediment—chemicals, metals, biotoxins—is now in the air you breathe into your lungs, potentially affecting your respiratory health.

The Hidden Risk of Mold

Even without full submersion, homes can suffer water intrusion through roofs, windows, and ventilation ducts. Damp materials create perfect conditions for rapid mold growth on decaying organic matter. Mold spreads by releasing tiny spores that float through the air and colonize other locations. While no indoor space is entirely free of spores, exposure to high concentrations is linked to respiratory complications such as:

  • Asthma
  • Allergic rhinitis
  • Sinusitis

Evidence from Past Storms

After Hurricane Katrina in New Orleans (2005), average outdoor mold concentrations in flooded areas were roughly double those in non-flooded areas, with the highest concentrations measured indoors. Studies of Katrina’s aftermath and the UK floods of 2007 showed that water damage accelerated mold growth and respiratory allergies.

Children’s Vulnerability

Children are especially susceptible to mold-related health problems. A study of young children in 30 Canadian communities found that homes reporting mold or dampness had higher rates of asthma, bronchitis, eye irritation, and cough. Other research links mold exposure to the development of asthma in children.

Factors Influencing Indoor Mold Growth

Our research after Hurricane Ida in New Orleans (2021) identified key factors impacting indoor mold and respiratory health:

  • Roof age: Older roofs were more prone to leaks and water intrusion.
  • Precautionary measures: The number of cleanup and protective steps taken after flooding.

Respiratory health impacts also varied with floodwater height, days per week spent at home, and the extent of precautionary measures taken.

Protective Measures and Recommendations

While you may not be able to entirely prevent flooding from major storms, taking proactive steps can help reduce respiratory health risks. The Environmental Protection Agency recommends limiting contact with floodwater, which may contain electrical hazards, raw sewage, and other hazardous substances. Taking such steps before and after a major storm goes a long way toward protecting your respiratory health.

Read Flooding Brings Deep Trouble in Harvard Medicine magazine to learn more about the health hazards related to floods.

```