CDC Health Concerns Associated with Mold in Water-Damaged Homes

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Health Concerns Associated with Mold in Water-Damaged Homes After

Hurricanes Katrina and Rita --- New Orleans Area, Louisiana, October

2005

http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5502a6.htm#tab

After Hurricanes Katrina and Rita made landfall on August 29 and

September 24, 2005, respectively, large sections of New Orleans

(Orleans Parish) and the three surrounding parishes (Jefferson,

Plaquemines, and St. Bernard) were flooded for weeks, leading to

extensive mold growth in buildings. As residents reoccupied the

city, local health-care providers and public health authorities were

concerned about the potential for respiratory health effects from

exposure to water-damaged homes. On October 6, CDC was invited by

the Louisiana Department of Health and Hospitals (LDHH) to assist in

documenting the extent of potential exposures. This report

summarizes the results of that investigation, which determined that

46% of inspected homes had visible mold growth and that residents

and remediation workers did not consistently use appropriate

respiratory protection. Public health interventions should emphasize

the importance of safe remediation practices and ensure the

availability of recommended personal protective equipment.

Housing Assessment for Mold and Mold Exposure

During October 22--28, a team representing CDC and LDHH assessed a

cross-section of the 440,269 households in the four-parish area (on

the basis of the 2000 U.S. Census). Sampling was restricted to

blocks with more than 20 housing units (areas with fewer housing

units are likely to be sparsely populated and to contain mostly

industrial buildings or parks) and areas where residents were

permitted entry, yielding 239,949 potential households (Figure).

Blocks were classified into three strata (mild, moderate, and

severe) on the basis of Federal Emergency Management Agency flood

and damage maps. Geographic information system (GIS) mapping

software was used to select a random number of waypoints (latitude

and longitude) proportionate for each stratum (1). A sample size of

88 homes was required to obtain estimates within 10% accuracy.

Global positioning system (GPS) units were used to locate each

waypoint as the random starting point to locate the nearest home at

or north of the waypoint.

In the sampled areas, 141 homes were found to be occupied. A

questionnaire on demographics, home occupancy, and participation in

remediation activities was administered to one consenting adult from

113 of the 141 homes in which someone was in the home. One

assessment was abandoned for safety reasons, resulting in a final

sample of 112. A standard instrument designed for this study and

pilot-tested with occupants of flood-damaged homes was used to

visually assess water damage and mold growth. Air samples were

collected at a subset of 20 homes; samples were collected for 36--

144 minutes with 0.4 µm, 37 mm polycarbonate closed-faced cassettes

at 3 L/min. The filters were analyzed for culturable fungi,

(1®3,1®6)-b-D-glucan (a cell-wall component of many fungi) (2), and

endotoxin (a cell-wall component of gram-negative bacteria) (3).

Of 112 homes inspected (Table), flood levels had been high (>6 feet)

in 21 (18.8%) homes, medium (3--6 feet) in 19 (17.0%), and low (<3

feet) in 72 (64.3%) (including 44 [39.3%] homes with no flooding).

Seventy-six (67.9%) homes had roof damage with water leakage.

Visible mold growth occurred in 51 (45.5%) homes, and 19 (17.0%) had

heavy mold coverage (>50% coverage on interior wall of most-affected

room). The distribution of homes with heavy mold coverage was 10

(52.6%), seven (36.8%), and two (10.5%) in high, medium, and low

flood areas, respectively.

Participants reported being indoors doing heavy cleaning an average

of 13 hours since the hurricanes (range: 0--84 hours) and 15 hours

doing light cleaning (range: 0--90 hours). Sixty-eight (60.7%)

participants reported inhabiting their homes overnight for an

average of 25 (standard deviation: +13.7) nights since the

hurricanes.

Indoor air samples were collected nonrandomly at 20 (16%) homes;

outdoor air samples were also collected for 11 of these homes.

Predominant fungi indoors and outdoors were Aspergillus spp. and

Penicillium spp. Geometric mean (1®3,1®6)-b-D-glucan air levels were

1.6 µg/m3 (geometric standard deviation [GSD]: 4.4) indoors and 0.9

µg/m3 (GSD: 2.0) outdoors; endotoxin levels were 23.3 EU/m3 (GSD:

5.6) indoors and 10.5 EU/m3 (GSD: 2.5) outdoors. Glucan and

endotoxin levels were significantly correlated (correlation

coefficient r = 0.56; p = 0.0095). The geometric mean glucan and

endotoxin levels were higher indoors compared with outdoors but the

differences were not statistically significant.

Survey of Residents and Workers Regarding Mold

During October 18--23, the assessment team conducted interviews with

residents and remediation workers in recently flooded communities at

three sites (i.e., the FEMA Disaster Recovery Center in St. Bernard,

a home improvement store in West Jefferson, and a grocery store in

East Jefferson) and at worker gathering places (e.g., work sites,

campsites, and social venues). A convenience sample of residents and

remediation workers with potential exposure to mold were asked

questions about their knowledge, attitudes, and practices regarding

mold; nonidentifying demographic information was also collected. A

total of 332 persons (workers and residents combined) were

approached for interviews; 235 (70.1%) participated. Interviews were

conducted in English and Spanish. A display of respirators was used

for reference during the interviews.

Of 159 residents interviewed, 82 (51.6%) were male; the overall mean

age was 51 years (range: 18--81 years). Nearly all (96.2%) residents

responded affirmatively to the question, " Do you think mold can make

people sick? " One hundred eight (67.9%) correctly identified

particulate-filter respirators as appropriate respiratory protection

for cleaning of mold. Sixty-seven (42.1%) had cleaned up mold; of

these, 46 (68.7%) did not always use appropriate respirators.

Reasons for not using respirators included discomfort (10 [21.7%]

respondents) and lack of availability (10 [21.7%]). For public

communications about potential risks from exposure to mold and the

use of personal protective equipment, 139 (87.4%) respondents

recommended the use of television or radio.

Seventy-six persons who self-identified as remediation workers were

interviewed. Of these, 14 (18.4%) were self-employed, and 62 (81.6%)

worked for a company doing remediation. Of the 76 workers, 70

(92.1%) were male; the mean age of respondents was 33 years (range:

18--57 years); 40 (52.6%) spoke only Spanish. Seventy-two (94.7%)

thought mold causes illness. Sixty-five (85.5%) correctly identified

particulate-filter respirators as appropriate protection for

cleaning of mold. Sixty-nine (90.7%) had already participated in

mold remediation activities at the time of the interview. Of these,

34 (49.3%) had not been fit tested for respirator use and 24 (34.8%)

did not always use appropriate respirators; 13 (54.2%) cited

discomfort as the reason for not using respirators. For worker

communications about potential risks from exposure to mold and the

use of personal protective equipment, 36 (47.4%) recommended use of

television or radio and 17 (22.4%) recommended communication through

employers.

Reported by: R Ratard, MD, Louisiana Dept of Health and Hospitals;

CM Brown, MBBS, J Ferdinands, PhD, D Callahan, MD, KH Dunn, MS, MR

Scalia, MPH, RL Moolenaar, MD, Div of Environmental Hazards and

Health Effects, National Center for Environmental Health; SI ,

MSPH, Div of Health Studies, Agency for Toxic Substances and Disease

Registry; Lynne Pinkerton, MD, Div of Surveillance, Hazard

Evaluations, and Field Studies, National Institute for Occupational

Safety and Health; C Rao, PhD, D Van Sickle, PhD, MA Riggs, PhD, KJ

Cummings, MD, EIS officers, CDC.

Editorial Note:

In 2004, the Institute of Medicine (IOM) reviewed the literature

regarding health outcomes related to damp indoor spaces (4). In

addition to the risk for opportunistic fungal infections in

immunocompromised persons, IOM found sufficient evidence for an

association between both damp indoor spaces and mold and upper

respiratory symptoms (nasal congestion and throat irritation) and

lower respiratory symptoms (cough, wheeze, and exacerbation of

asthma). The findings of this report indicate that, in the New

Orleans area post-hurricane, indoor environmental conditions and

personal practices provided exposures that potentially put residents

and remediation workers at risk for these negative health effects.

This study used markers that have been used in exposure assessments

in water-damaged buildings, including cultured fungi and microbial

structural components (bacterial endotoxins and fungal glucans).

Interpreting the significance of these measures is not

straightforward, and health-based indoor exposure limits for these

compounds have not been established (4,5). Previous measurements of

airborne endotoxin in homes have averaged <1.0 EU/m3, with indoor

levels generally lower than outdoor ones (6). In post-hurricane New

Orleans homes, mean indoor endotoxin levels were more than 20 times

higher than the 1.0 EU/m3 average, with an inversion of the expected

indoor-outdoor relationship. This mean level exceeds that associated

with respiratory symptoms in one study (7). In five New Orleans

homes, the measured indoor endotoxin levels were comparable to those

of certain industrial settings in which declines in pulmonary

function have been demonstrated (8).

Exposure to (1®3)-b-D-glucan, a cell-wall component not specific to

fungi, has also been linked to respiratory health effects in certain

studies (5). In this assessment, a newer assay for (1®3,1®6)-b-D-

glucan (2), a different glucan with higher specificity for fungi,

yielded higher indoor than outdoor levels in New Orleans homes.

Although differences in the two glucan assays preclude direct

comparisons, the findings of this assessment indicated that mold

growth inside homes was likely at or above a level sometimes

reported to be associated with certain health effects (e.g., cough;

airway hyper-reactivity; influenza-like symptoms; ear, nose, and

throat irritation; decreased lung function; and skin rash) (5).

In October 2005, the CDC Mold Work Group published guidelines for

remediation workers and the public on preventing mold-associated

illness in areas affected by hurricane-related flooding (9).

Recommendations included avoiding exposure when possible and using a

particulate-filter respirator during activities that create mold-

contaminated dust. Despite their awareness of health effects

associated with mold, one third of a convenience sample of residents

could not identify an appropriate respirator, and the majority of

those participating in mold-remediation activities reported doing so

without consistently using respiratory protection. Although the

majority of remediation workers reported consistently using an

appropriate respirator, one third still failed to do so. Even those

workers who used respiratory protection consistently might not have

benefited from its full effectiveness; only half of the workers

reported having had a respirator fit test, an Occupational Safety

and Health Administration (OSHA) requirement (10).

The findings of this report are subject to at least three

limitations. First, because homes at which persons were present

likely had less water damage and mold than homes that were

unoccupied at the time of the study, this study might have

underestimated the extent of mold-contaminated homes. Second, air-

sampling results might not be representative because a convenience

sample was used and because sampling occurred after six homes had

been remediated. Finally, residents and workers surveyed were not

randomly selected and might not be representive of their respective

populations.

This report provides an early assessment of the impact of water

damage and mold growth in the New Orleans area after Hurricanes

Katrina and Rita. This assessment benefited from the random sampling

method used to assess homes and the survey of remediation workers, a

group with high potential for exposures. Results of this assessment

should be used to guide future public health interventions in this

setting and after other catastrophic floods. Specifically, measures

to increase awareness of appropriate respiratory protection among

the public are warranted. This could be carried out via traditional

media announcements and educational sessions for employees of home

improvement stores and other commercial entities that sell

respirators. Public availability of particulate-filter respirators

might be increased through partnerships with respirator

manufacturers. For remediation workers, the importance of

appropriate respiratory protection should be emphasized via

traditional media announcements and/or employers, with messages in

both English and Spanish. Fit testing should occur according to the

OSHA Standard (10); making such services available to small or

individual operators might increase compliance with requirements.

Given the extent of flooding in the New Orleans area, exposure to

water-damaged buildings and mold will likely be an ongoing problem;

investigation of sentinel clinical case reports might enable primary

and secondary prevention of exposure-related respiratory disease.

Acknowledgments

This report is based, in part, on data contributed by GL Chew, ScD,

Mailman School of Public Health, Columbia University, New York, New

York; PS Thorne, PhD, College of Public Health, University of Iowa,

Iowa City, Iowa; M Muilenberg, MS, School of Public Health, Harvard

University, Boston, Massachusetts; H Alsdurf, School of Public

Health and Tropical Medicine, Tulane University, New Orleans,

Louisiana; D Dyce, C Muller, Office of Inspector General, US

Department of Health and Human Services; J-H Park, ScD, K Kreiss,

MD, Division of Respiratory Disease Studies, M Hein, MS, P Laber,

MS, F Armstrong, N Burton, MPH, Division of Surveillance, Hazard

Evaluations, and Field Studies, National Institute for Occupational

Safety and Health; WR Daley, DVM, Office of Workforce and Career

Development; S Hurston, Division of Sexually Transmitted Disease

Prevention, National Center for HIV, STD, and TB Prevention; S

Benoit, MD, R Noe, MPH, A Sumner, MD, EIS officers, CDC.

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Table

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Date last reviewed: 1/19/2006