Flood events continue to occur globally, causing severe impacts on our economy, environment, and society. Floods are well known for their devastating immediate effects, but what often goes unnoticed is the negative impact they have on indoor environments. Specifically, the growth of mold spores post-flood poses significant respiratory health challenges. There has been a lack of quantitative models to predict the growth of indoor mold following flood events. To address this, we used fine-scale data collected from buildings affected by Hurricanes Ida and Ian and developed the first quantitative models using machine learning to predict the impacts of flooding on indoor mold spores, opening new avenues for comprehensive flood damage assessments.
5 Key Factors that Drive Mold Growth in Buildings after Hurricanes
Our research utilized a comprehensive, fine-scale, building-level database gathered from 60 homes affected by Hurricanes Ida (2021) and Ian (2022) across four U.S. states: Louisiana, New York, New Jersey, and Florida. We applied innovative machine learning algorithms to predict mold spore levels. Out of the 15 factors investigated in this study, we identified five as the most important for predicting indoor mold.
- Building air tightness
- Average bathroom exhaust fan airflow rate
- Window blind status
- Roof age
- Maximum flood depth
Dr. Parham Azimi, Research Associate on the Healthy Buildings team who led the field assessment efforts, stated, “Flood events cause immense damage, yet the silent threat to indoor air quality remains overlooked. With our comprehensive model, we not only predict the impacts of flooding on mold presence in indoor environments but also illuminate the key factors—like ventilation and flood depth—that can inform mitigation measures.”
Dr. Ebrahim Ahmadisharaf, the Principal Investigator of the study from FSU who led the modeling efforts, emphasized the broader outcomes, saying, “The model can be utilized to quantitatively assess the impacts and get a better picture of a range of flood damages, while the identified key factors would inform us about what needs to be done to prevent such impacts.”
Looking Ahead
Future research should focus on collecting data that allows us to track changes in mold spores in the aftermath of hurricanes. Such studies should then be complemented with direct health modeling efforts that enable us to predict the indirect health-related impacts of flooding. Expanding the sample size and scope of data collection will provide new insights and develop strategies that protect respiratory health, reinforcing the foundation laid by our current study.
Zahra Keshavarz, Research Assistant on the Harvard Healthy Buildings team and a member of the study team added, “Our findings are a testament to interdisciplinary collaboration. By integrating environmental engineering with public health, we facilitate the design of more resilient indoor environments, ensuring that public health is protected long after flooding events.”
Read the full paper here:
https://www.sciencedirect.com/science/article/pii/S0160412025000704
Additional Resources: