The effects of air cleaners on hay fever symptoms in air-conditioned homes

Abstract

High-efficiency air cleaners that remove 99% of particles greater than 6 μ from the air are now available. We performed an 8-wk prospective double-blind crossover study of the efficacy of the addition of these cleaners to home central air conditioning. Twenty adults, allergic to ragweed, Alternaria, or both, kept daily medication records and symptom scores. We recorded daily outdoor pollen and mold counts, bimonthly inside and outside the home pollen and mold counts, and a physician's evaluation of efficacy. When the cleaners were in place, there was a trend toward lower symptom scores and also daytime and evening scores. Only the decrease in symptoms which occurred during night hours when the cleaners were in place were statistically significant. The correct sequence of cleaner placement was identified in 14 of the 20 cases. We conclude that the addition of a high-efficiency central air cleaner may add minimal improvement in hay fever to that provided by central air conditioning alone. The practical value of the device remains to be determined.