京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第12794号 / 論農博第2790号 / 新制||農||1019(附属図書館) / 学位論文||H25||N4806(農学部図書室) / 30813 / (主査)教授 栗原 達夫, 教授 植田 和光, 教授 平竹 潤 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Asthma is the leading chronic illness in children in the United States. Since children in the U.S. spend a majority of their time indoors there is an increased need to understand key sources of daily asthma triggers in the home. Bacterial endotoxin, dust mite allergens and β-D-glucan have been shown to be potent inducers of asthma attacks, and high levels of these allergens in homes can trigger attacks in those with asthma. We aim to better understand the risks to those with asthma that might be associated with evaporative cooler (EC) use in low-income homes. ECs are often promoted because of their low energy consumption and decreased environmental impact compared to central air conditioning (AC). Because of their lower cost, ECs are more widely used in low-income homes. ECs use evaporation to cool the air, which leads to higher indoor relative humidity. This may create an ecological niche for house dust mites in semi-arid climates where they are normally absent. EC sump water also provides an ideal environment for bacteria and fungi to grow, possibly resulting in EC loading the air with more potential asthma triggers than central air conditioning. We sampled low-income homes around Utah county with central air and evaporative cooling and tested them for the presence of dust mite allergens, β-D-glucan and endotoxin. There were significantly higher levels of endotoxins and β-(1→3)-D-glucans in the EC homes compared to the AC homes, with increased odds of dust mite allergen prevalence but not at clinically significant levels. These findings suggest that in semi-arid environments, endotoxin and β-(1→3)-D-glucan levels in homes with evaporative coolers are more elevated than dust mite allergens.