Conference Coverage

Swamp coolers not linked to dust mite sensitization in atopic children

 

Key clinical point: No difference was seen in sensitization to house dust mites and mold between pediatric atopic patients who used swamp coolers and those who didn’t.

Major finding: Researchers found that 29% of those with swamp coolers were dust-mite positive on skin testing, and 28% of those without one were as well. This was not a significant difference (P = .85).

Study details: A retrospective review of more than 17,000 cases of atopic children aged 21 years and younger who were seen at National Jewish Health and had a positive environmental skin prick test.

Disclosures: Dr. Izadi had no relevant financial disclosures.

Source: Izadi N et al. AAAAI/WAO Joint Congress, Abstract 586

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Susan Millard, MD, FCCP

Susan Millard, MD, FCCP, comments: Swamp coolers are used in semi-arid and arid climates like Arizona, where I did my fellowship training but they didn't work well to keep apartments and homes cool enough if over about 100°F outside! The system is cheaper than air conditioning. So it is great to know that this type of cooling system does not cause more mold and dust mite allergies.


 

REPORTING FROM AAAAI/WAO JOINT CONGRESS

– Swamp coolers – a low-cost alternative to air-conditioning in dry regions – weren’t found to increase sensitization to house dust mites or mold in atopic pediatric patients, researchers reported.

Neema Izadi, MD, and his associates say the findings, seen in a pediatric Colorado population in a study evaluating data over 10 years, could mean that not everyone at risk of dust mite and mold sensitization needs to avoid these cooling systems.

Dr. Neema Izadi is a pediatric allergy and immunology fellow at National Jewish Health, Denver

Dr. Neema Izadi

Swamp coolers, or evaporative coolers, draw water from a reservoir with a pump and the water is placed on a cooling pad. Then a fan pulls the air through the pad. This cools the air inside the home, but also increases the moisture in the air.

“Evaporative coolers have been shown to raise relative humidity by about 10%,” said Dr. Izadi, a pediatric allergy and immunology fellow at National Jewish Health, Denver, presenting at the joint congress of the American Academy of Asthma, Allergy and Immunology and the World Asthma Organization. “They work best in environments where the air is very warm and dry.”

House dust mites and mold thrive in higher humidity. Small studies performed in Colorado, Utah, and other locations have shown that the swamp coolers increase house dust mite allergen content, but there have been very few studies that have looked at actual sensitization. One smaller study in Nevada did find that the coolers increased sensitization to dust mites and mold.

In this study – thought to be the largest ever to look at this question – Dr. Izadi and his colleagues assessed data on patients aged 21 years and younger who were seen at National Jewish Health during 2008-2017 and who had at least one positive environmental skin-prick test. The average age was about 9 years. The cohort included 8,503 patients with sensitization to house dust mites and 9,286 with sensitization to mold. Researchers examined data on swamp coolers in their homes.

The researchers found that 29% of those with swamp coolers were dust-mite positive on skin testing, and 28% of those without one were positive. This was not a significant difference (P = .85). They found that 45% of those with the coolers were positive for sensitization to any mold, compared with 44% without one – also not a significant difference (P = .43).

They also found no difference according to age group, sex, or individually for atopic dermatitis, asthma, or allergic rhinitis.

He acknowledged that the study had no way to reliably account for patients who were transplants to Colorado, having moved there from somewhere else. The study also didn’t examine the age of homes, whether it had carpeting, or other factors.

He noted that the amount of time the coolers were run in the home was not examined and that “it might matter how much it is on.” This, he said, might account for differences in these results, compared with the Nevada study that did find a sensitization increase cause by the coolers.

“Evaporative coolers or swamp coolers are a great low-cost alternative in semiarid and arid environments – they can cut costs from 15%-35%,” Dr. Izadi said. “These data may indicate that it may be unnecessary to recommend that patients remove their swamp cooler, at least from a dust-mite and mold-sensitization standpoint.”

Dr. Izadi had no relevant financial disclosures.

SOURCE: Izadi N et al. AAAAI/WAO Joint Congress, Abstract 586

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