Airborne Mold and Endotoxin Concentrations in New Orleans, Louisiana, after Flooding, October through November 2005

Abstract

BackgroundThe hurricanes and flooding in New Orleans, Louisiana, in October and November 2005 resulted in damp conditions favorable to the dispersion of bioaerosols such as mold spores and endotoxin.ObjectiveOur objective in this study was to assess potential human exposure to bioaerosols in New Orleans after the flooding of the city.MethodsA team of investigators performed continuous airborne sampling for mold spores and endotoxin outdoors in flooded and nonflooded areas, and inside homes that had undergone various levels of remediation, for periods of 5–24 hr during the 2 months after the flooding.ResultsThe estimated 24-hr mold concentrations ranged from 21,000 to 102,000 spores/m3 in outdoor air and from 11,000 to 645,000 spores/m3 in indoor air. The mean outdoor spore concentration in flooded areas was roughly double the concentration in nonflooded areas (66,167 vs. 33,179 spores/m3; p < 0.05). The highest concentrations were inside homes. The most common mold species were from the genera of Cladosporium and Aspergillus/Penicillium; Stachybotrys was detected in some indoor samples. The airborne endotoxin concentrations ranged from 0.6 to 8.3 EU (endo-toxin units)/m3 but did not vary with flooded status or between indoor and outdoor environments.ConclusionsThe high concentration of mold measured indoors and outdoors in the New Orleans area is likely to be a significant respiratory hazard that should be monitored over time. Workers and returning residents should use appropriate personal protective equipment and exposure mitigation techniques to prevent respiratory morbidity and long-term health effects.

Mold Exposure and Health Effects Following Hurricanes Katrina and Rita

“…In most cases, the level of mold indicators from air samples taken inside flood-damaged homes was higher than in samples taken from outdoor air (12,17,42,45,47,49). Aerosolized spores from the outside environment may be carried indoors.…”

“…Homes in the most severely affected areas were not sampled because access to these areas was restricted at the time of the investigations. These reports, therefore, likely underestimate the extent of mold growth (49) in the months following Hurricanes Katrina and Rita.…”

“…Because some fungi are difficult to grow on culture media, total spore counts may be a more sensitive indicator of the fungal diversity in an environment. They may also be better indicators of potential adverse health effects related to mold exposures because nonviable spores can trigger allergic reactions or carry other allergens that result in illness (49). However, because spores of different molds often look alike on microscopy, it may not be possible to differentiate molds into specific species using spore collection alone.…”

“…Furthermore, different fungal species release their spores at different times during the day or year, and some species are more prolific than others (30). Short sampling periods may miss important episodes of spore release, resulting in sampling error and reduced accuracy in estimating 24-h spore concentrations (49).…”

Adjuvant effect of zymosan after pulmonary treatment in a mouse ovalbumin allergy model

“…Filamentous microfungi (mold) can become airborne and threaten human health after inhalation [1]. Both fungi and molds are ubiquitous and exist in the natural environment in indoor and outdoor settings.…”