Indoor air in public facilities contains various pollutants jeopardizing the health of employees or occupants in the facilities. We evaluated the respiratory allergy-related immune status of employees, and investigated a role of genetic predisposition on respiratory allergy occurrence in the employees. Among 23 workers from 5 facilities, 48% were positive for aeroallergens. House dust mite was the major allergen demonstrating positive skin reactions. The level of plasma IgE, an immunologic marker for allergic hypersensitivity induction, was upregulated in the allergy positive employees. The percentage of eosinophils in peripheral blood was also higher in the allergy positive employees than in the employees with negative skin test results. We also evaluated genetic polymorphisms on interleukin-4 (IL-4) receptor alpha chain (Gln576Arg and Ile50Val), IL-4 (C589T) and interleukin-13 (Arg130Gln), which has been implicated in asthma induction in children. However, no higher frequencies of these genetic variations were found in the adults with positive skin test results for aeroallergens. This study implies that workers in social welfare facilities may have a substantial risk of suffering from respiratory allergy associated with exposure to aeroallergens, but genetic variations in the IL-4 receptor alpha chain, IL-4 and IL-13 may not be critical in adult workers for the development of respiratory allergic diseases.