Dampness and Mold From Severe Storms and Flooding

Climate change is expected to increase the frequency, intensity and amount of heavy precipitation, and the frequency and strength of tropical cyclones [22, 23]. Climate change is also increasing sea level [22, 23]. Globally, sea level is projected to increase by 0.26 to 0.82 m [0.9 to 2.7 ft.] by 2100 [22]. Increased sea level, coupled with storm surges, increases flooding in coastal areas. Melillo [10] has projected that climate change will increase flooding in much of the U.S.

Flooding and water entry into buildings during periods of heavy rain and high winds are a cause of building water damage and associated increases in mold and bacteria on building surfaces [24]. In turn, dampness and mold in buildings is associated with increases in respiratory symptoms, asthma, and respiratory infections [24-29].

Because climate change is expected to increase dampness in mold in buildings, climate change is expected to increase the adverse health effects associated with building dampness and mold. With existing data, the amount of increase in these adverse health effects cannot be predicted. However, calculations indicate substantial health effects from even moderate increases in building dampness and mold [1]. The estimated effects of a 25% increase in building dampness and mold include 1.2 million additional cases of current asthma with an annual cost of approximately $1 billion, a 2% to 5% increase in common respiratory infections, and, with less certainty, 0.4 million additional days of sick leave in U.S. office workers per year, with an economic effect of $125 million [1].

Potential mitigation measures include changes in building envelope design and construction practices to reduce the potential for water entry. Improved maintenance of building envelopes can also reduce dampness problems, for example replacing roofs before they leak and fixing leaks quickly after they are detected. Also, elevating buildings above grade level (e.g., supporting buildings on raised piers) in flood-prone locations and locating fewer buildings in flood plains, can reduce the extent to which climate change increases dampness and mold in buildings. Construction of sea walls could reduce coastal flooding during storm surges. Most of these actions make good sense, irrespective of climate change, as building dampness and mold in the current climate are a significant source of adverse health effects and impose high costs for building repairs and mold remediation. More information on measures to reduce building dampness and mold is provided elsewhere in this web site and the U.S. Environmental Protection Agency's Indoor Air Quality (IAQ) pages.