Resident cleanup activities, characteristics of flood-damaged homes and airborne microbial concentrations in New Orleans, Louisiana, October 2005

doi:10.1016/j.envres.2007.11.004

Environmental Research

Volume 106, Issue 3, March 2008, Pages 401-409

https://doi.org/10.1016/j.envres.2007.11.004 Get rights and content

Abstract

Background

Flooding in the greater New Orleans (GNO) area after the hurricanes caused extensive mold growth in homes resulting in public health concerns.

Objectives

We conducted an environmental assessment of homes to determine the extent and type of microbial growth.

Methods

We randomly selected 112 homes, stratified by water damage, and then visually assessed mold growth. Air samples from a subset of 20 homes were analyzed for culturable fungi, fungal spores, and markers of mold ((1→3, 1→6)-β-d-glucans) and bacteria (endotoxin).

Results

Visible mold growth occurred in 49 (44%) homes; 18 (16%) homes had >50% mold coverage. Flood levels were >6 ft at 20 (19%), 3–6 ft at 20 (19%), and <3 ft at 28 (26%) homes out of 107; no flooding at 39 (36%) homes. The residents spent an average of 18 h (range: 1–84) doing heavy cleaning and of those, 22 (38%) reported using an N-95 or other respirator. Visible mold growth was significantly associated with flood height ⩾3 ft and the predominant fungi indoors were Aspergillus and Penicillium species, which were in higher concentrations in homes with a flood level ⩾3 ft. Geometric mean (GM) levels of endotoxin were as high as 40.2 EU/m³, while GM glucan levels were as high as 3.5 μg/m³ even when flooding was ⩽3 ft.

Conclusions

Based on our observations of visible mold, we estimated that elevated mold growth was present in 194,000 (44%) homes in the GNO area and 70,000 (16%) homes had heavy mold growth. Concentrations of endotoxin and glucans exceeded those previously associated with health effects. With such high levels of microbial growth following flooding, potentially harmful inhalation exposures can be present for persons entering or cleaning affected homes. Persons exposed to water-damaged homes should follow the CDC recommendations developed following the 2005 hurricanes for appropriate respiratory precautions.

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.

Section snippets

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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Resident cleanup activities, characteristics of flood-damaged homes and airborne microbial concentrations in New Orleans, Louisiana, October 2005

Abstract

Background

Objectives

Methods

Results

Conclusions

Introduction

Section snippets

Study population

Participation rates

Demographics

Discussion

Recommendations

Acknowledgments

Int. Biodeterior. Biodegr.

Toxicology

Dampness in buildings and health

Indoor Air

Health concerns associated with mold in water-damaged homes after Hurricanes Katrina and Rita—New Orleans, Louisiana, October 2005

MMWR

Mold prevention strategies and possible health effects in the aftermath of hurricanes and major floods

MMWR

Mold-related knowledge, attitudes, and practices of residents and remediation workers in post-hurricane New Orleans

Arch. Environ. Occup. Health

Measurement of b(1–3)-glucans in occupational and home environments with an inhibition enzyme immunoassay

Appl. Environ. Microbiol.

Worker exposures to airborne dust, endotoxin and b(1,3) glucan in two New Zealand sawmills

Am. J. Ind. Med.

A comparison of airborne ergosterol, glucan and air-O-cell data in relation to physical assessments of mold damage and some other parameters

Indoor Air

Levels of household mold associated with respiratory symptoms in the first year of life in a cohort at risk for asthma

Environ. Health Perspect.

Microfungal contamination of damp buildings—examples of risk constructions and risk materials

Environ. Health Perspect.

Characterization and variability of endotoxin and 3-hydroxy fatty acids in an office building during a particle intervention study

Indoor Air

Damp Indoor Spaces and Health

Endotoxins in the environment

Int. J. Occup. Environ. Health