Hurricane Katrina was the most economically destructive storm in U.S. history [21
]. The loss of life and property damage were exacerbated by the levee breaks; at least 80% of New Orleans was reported to be flooded 2 days after the hurricane struck, with some areas having as much as 20 feet of flood water [1
]. Public officials and citizens of New Orleans expressed concern that the resulting high levels of mold and other toxic environmental exposures could aggravate existing respiratory disease and cause additional deleterious health effects [22
]. These concerns were especially great for those children with asthma in New Orleans, where some of the country's highest rates of this disease have long been documented [23
]. The HEAL project measured the environmental allergen concentrations in post-Katrina New Orleans within the homes of children with asthma and provided support for their healthcare through environmental and AC interventions that were shown to be effective in the inner-city environment.
The environmental impact of Hurricane Katrina was devastating, so much that 94% of the families enrolled in the HEAL project moved at least once following the disaster, and many moved more than 2 or even 4 times to find acceptable housing. Remediation of the Katrina damage began shortly after the hurricane and continued for years. During this study, the environmental conditions improved rapidly, with 68% of the study participants initiating renovations that continued throughout the HEAL study period. In fact, many HEAL children and their caregivers had moved to new residences (49%) or completed home renovations (47%) before enrollment in HEAL. While HEAL children and caregivers moved and rebuilt, airborne mold declined from the peak levels that occurred immediately after the storm. The average airborne mold levels measured at HEAL baseline were markedly lower (501
indoors) than measurements taken immediately after Katrina (11,000–645,000
The development of allergen sensitivities can begin at a very early age and, therefore, is difficult to link to short-term exposures, especially those later in life. Increased exposures to allergenic risk factors, such as allergens and molds, can dramatically increase asthma morbidity [26
]. Mold skin test sensitivities in HEAL children were significantly higher than those observed in other inner city populations [8
], but we were not able to detect a significant difference in asthma symptoms or healthcare utilization in this cohort that was followed a few years after Hurricane Katrina.
Levels of common household dust allergens, with the exception of mold, were lower in HEAL homes than the levels reported in comparable inner-city studies. For example, 20% of the homes of HEAL children had detectable levels of cockroach (Bla g 1) in their bedrooms, and only 4% had levels greater than 2
U/g, which is considered the threshold for skin sensitization [27
]. In comparison, 32% of ICAS children had detectable levels of cockroach in their bedrooms, and 12% had levels above 2
]. Similarly, HEAL dust allergen levels were lower than comparable dust allergen measurements taken pre-Katrina (20% versus 57% >2
U/g cockroach; 9% vs. 46% >2μ
g/g Der p 1) [28
]. Clearly, moving to a cleaner home combined with the measures taken to clean damaged HEAL homes led to the lower levels that were observed and the apparent disconnect between post-Katrina allergen levels and observed sensitization rates. While we do have preremediation/prerenovation dust allergen data from some HEAL homes (those who remediated and renovated during HEAL), the number of such homes was too few to make any meaningful comparisons. It is possible that HEAL children were exposed to high allergen levels in locations other than their homes, such as schools or homes of relatives or friends, causing them to become sensitized; however, environmental sampling for HEAL was not conducted in locations other than the children's homes. Also, it is possible that results could have been impacted when bed dust samples were supplemented or replaced with bedroom floor samples because the quantity of bed dust was insufficient for analysis; however, low levels of dust allergens were found across all of the samples regardless of if they were strictly collected from the bed or combined or replaced with bedroom floor samples. The low allergen levels found in the bed/bedroom dust of HEAL children allowed little opportunity to differentiate between “high” and “low” concentrations or to test for relationships with sensitivity.
As previously mentioned, unlike the other dust allergen concentrations, Alternaria
dust allergen was found in the majority of all bedrooms (98%) and found at concentrations >10μ
g/g in 58% of bedrooms. This finding requires further investigation; in addition, potential implications have been previously discussed [17
], including the most likely reason being that this may not only just represent Alternaria
but may be an artifact from the polyclonal antibody used to detect Alternaria
cross-reacting with other fungi, such as those belonging to the Pleosporaceae family (Alternaria, Ulocladium, Stemphylium
) and other dematiaceous genera including Epicoccum
For asthma morbidity, previous studies have shown that cockroach, dust mite, and cat exposure are linked to asthma symptoms in sensitized individuals [26
]. Exacerbations have also been documented with dog, mouse, and Alternaria
allergen exposures [31
]. In HEAL, no similar positive relationships were observed between asthma symptoms and the allergen concentration/sensitivity groups. In the interesting case of airborne mold and morbidity, a robust inverse relationship was observed at baseline; however, this same inverse finding was not seen during followup measures at 6 and 12 months, so a causal relationship is unlikely. While mold levels were high shortly after Hurricane Katrina [15
], research less than 1 year after Katrina found that mold levels and respiratory symptoms had decreased and that mold levels in homes with hurricane damage had returned to moderate levels [34
]. These findings are consistent with the modest environmental allergen levels observed in HEAL and support the notion that residents renovated their homes or moved to cleaner environments upon returning to NO. This rapid change from a flooded, high-mold environment to a relatively clean environment somewhat limits the clinical utility of the single exposure measurements taken 18 months after Katrina. The low level of environmental allergen concentrations is the most obvious reason for the lack of significant relationships between asthma morbidity and the airborne mold concentrations, dust-borne allergen levels, and skin test sensitivities observed in HEAL. It would be interesting to prospectively reexamine these relationships in HEAL children to see if environmental allergen concentrations increase as the disaster conditions fully stabilize and the renovated homes return to their pre-Katrina state.