Resident cleanup activities, characteristics of flood-damaged homes and airborne microbial concentrations in New Orleans, Louisiana, October 2005
Introduction
Hurricane Katrina made landfall on August 29, 2005, as a category 3 hurricane with the center of the eye hitting Plaquemines Parish, Louisiana (Fig. 1). Within 4 weeks, on September 24, 2005, Hurricane Rita made landfall near the Texas–Louisiana border. The storm surge, rainfall, and high winds associated with these hurricanes caused extensive damage to Orleans, Jefferson, Plaquemines, and St. Bernard Parishes, Louisiana. Over 80% of New Orleans was flooded for more than 2 weeks after the levee system throughout the city was breached (Knabb et al., 2005). The duration and extent of flooding as well as the number of structures flooded and warm temperatures led to massive mold growth throughout the area after flood waters receded (Centers for Disease Control and Prevention (CDC), 2006a).
The health consequences of residential exposure to high concentrations of fungal and bacterial agents or specific fungal genera after floods are not well characterized. However, the Institute of Medicine (IOM) report entitled Damp Indoor Spaces and Health concluded that exposures to mold are associated with respiratory illnesses and that immunocompromised persons are at risk for fungal colonization and opportunistic infections (IOM, 2004). Recent parallels to the degree of flooding seen in post-hurricane New Orleans occurred in 1997 in Grand Forks, North Dakota, and in 1999 in North Carolina after Hurricane Floyd (National Institute for Occupational Safety and Health (NIOSH), 1999). In North Carolina, there was a reported increase in persons presenting with asthma symptoms and this was postulated to be due to storm-related mold exposure (National Institute for Occupational Safety and Health (NIOSH), 1999). Flooding and subsequent mold growth on the Turtle Mountain reservation in North Dakota was associated with self-reported rhinitis, rash, headaches, and asthma exacerbation (Stock et al., 2005).
Physical evidence (e.g., visual and olfactory) of mold and water-damage in buildings has been associated with an increased risk of respiratory health outcomes among occupants (Bornehag et al., 2001). Air-sampling also is widely used for fungal exposure assessment; however, interpretation of results is difficult as no health-based standards exist. Environmental testing may not be possible when flood damage is wide spread and cleanup needs to begin without the benefit of such information. Some non-specific sampling methods allow estimation of fungal and bacterial biomass by measurement of cell wall or membrane components through biological assays. Two of these components, glucans and endotoxins, have been shown to induce inflammatory responses and are specific microbial agents that may allow accurate determination of exposures in relation to health effects (Martinez et al., 2004).
After the massive flooding in the greater New Orleans (GNO) area, the CDC, Louisiana health officials, and the general public were concerned about possible health effects for residents returning to mold-contaminated buildings (CDC, 2006a). The conditions in the GNO area, reoccupation, and cleanup practices presented opportunities for the residents to be exposed to mold and other particulate matter. Because of these concerns, we conducted an investigation to assess mold exposure in flood-damaged homes. This cross-sectional survey combined subjective assessments of mold contamination (resident questionnaire and visual inspection of homes) with airborne fungal and endotoxin sampling to evaluate flood damage in residential areas of New Orleans. The objectives were to characterize the type and extent of mold growth in homes, identify predictors of mold growth, describe resident activity in homes, and determine the types of respiratory protection used during cleanup activities.
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Study population
The GNO population for this cross-sectional survey included 440,269 households in four parishes based on 2000 US Census data. Sampling was restricted to blocks with more than 20 housing units yielding 239,949 potential households. Blocks were classified into three strata (mild, moderate, and severe water and wind damage) on the basis of Federal Emergency Management Agency (FEMA) flood and damage maps (Fig. 1). Geographic information system (GIS) mapping software (ArcGIS Version 9.1, ESRI,
Participation rates
We approached 146 homes at which someone was present. At 113 of these homes, an adult agreed to participate, yielding an overall participation rate of 77%. We were unable to complete one survey because of safety hazards in the home. Surveys were completed for the remaining 112 households.
Demographics
The median age of the 112 respondents was 52 (range: 18–85) years. There were 59 (53%) males and of the 109 persons who chose to identify their race, 76 (70%) were white, 25 (23%) were black, and 8 (7%) were
Discussion
Hurricanes Katrina and Rita resulted in devastating floods causing extensive mold growth in homes throughout the GNO area. Our assessment demonstrated that substantial concentrations of mold and microbial products existed in a large number of GNO area homes. Therefore, as will be discussed later, post-flood conditions and cleanup practices provided exposures that may have put residents at risk for potentially developing respiratory symptoms and fungal infections.
A majority of the homes in our
Recommendations
The findings of this investigation support the CDC recommendations for mold prevention strategies to reduce possible health effects in the aftermath of major floods (CDC, 2006b). These precautions include avoidance of unnecessary exposure to mold-contaminated areas, particularly for immunocompromised persons and those with allergy-related illnesses. Public health officials should promote public awareness of appropriate respiratory protection and remediation practices for persons who will be
Acknowledgments
We thank Ginger Chew, Peter Thorne, and Mike Muilenberg for laboratory analyses; Josh Mott and Juliette Morgan for study design; Marissa Scalia, Deann Ryberg, Kathy Sunnarborg, Patty Laber, Faith Armstrong, and Misty Hein for data collection/entry/management/analysis; Hannah Alsdurf, Special Agents Dennis Dyce and Curt Muller for logistics and staff support.
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