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

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 micrograms/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 micrograms/gm dust or greater, but only 5 of 95 control samples (5.2%) had levels of 2 micrograms/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.