The prevalence of Dermatophagoides mite allergen in Colorado homes utilizing central evaporative coolers

Abstract

Objective: The prevalence of mite allergen was studied in homes in which the indoor relative humidity may be increased by use of an evaporative cooler. Methods: Colorado homes in which central evaporative coolers are used and control homes were evaluated. ELISAs with monoclonal antibodies specific for Der p 1 and Der f 1 were performed on dust samples from each home in May and August. Indoor relative humidity and temperatures were recorded daily. Results: May samples did not show significant levels of mite allergen (< 2 μg/gm dust). Of the August samples, 48 of 95 samples from homes with evaporative coolers (50.5%) had levels of Der p 1 and Der f 1 of 2 μg/gm dust or greater, but only 5 of 95 control samples (5.2%) had levels of 2 μg/gm dust or greater ( p < 0.00001). Twelve of 19 homes with evaporative coolers (63%) were positive for mite allergen. Five of 19 (26%) control homes were positive ( p < 0.05). The homes with evaporative coolers had average indoor relative humidity of 51% or greater: control homes had average relative humidity of less than 45%. Conclusion: Altering the indoor environment by raising indoor relative humidity through use of evaporative coolers leads to conditions that may facilitate Dermatophagoides survival. ( J Allergy Clin Immunol 1995;96:473-9.)