Mechanical ventilation and high-efficiency vacuum cleaning: A combined strategy of mite and mite allergen reduction in the control of mite-sensitive asthma

Background: The relationship between exposure to house dust mite (HDM) alle rgens and prevalence of sensitization to these allergens in patients with a sthma has been confirmed in many studies. Mite population growth is regulat ed by humidity. Reducing humidity and removing allergen by efficient vacuum ing should control mite allergen and reduce symptoms. Objective: We sought to investigate the effect of mechanical ventilation an d high-efficiency vacuuming on HDM numbers and Der p 1 concentrations in th e homes of mite-sensitive asthmatic subjects and to evaluate the effect of any reductions on symptoms. Methods: The homes of 40 HDM-sensitive asthmatic subjects were randomized t o receive (1) mechanical ventilation and a high-efficiency vacuum cleaner ( HEVC); (2) mechanical ventilation alone; (3) an HEVC alone; and (4) no inte rvention. Homes and patients were monitored for 12 months. Change in absolu te humidity, mite numbers, Der p 1 concentrations, lung function, bronchial hyperresponsiveness, and symptom scores were analyzed. Results: Homes with mechanical ventilation achieved significantly Lower hum idity levels than those without (P < .001), with an associated reduction of mite numbers (P < .05) and Her p 1 concentrations (P < .001 [in nanograms per gram], P = .006 [in milligrams per square meter]) in bedroom carpets an d some other mite sources in the ventilated areas of the homes. The additio n of a vacuum cleaner enhanced this effect. There was a trend for an improv ement in histamine PC20 (P =.085) in the patients whose homes were ventilat ed. Conclusion: The use of a mechanical ventilation system in suitable homes re sulted in some reduction in numbers of HDM and Der p 1 concentrations. The addition of an HEVC slightly enhanced the effect but not sufficiently to se e an improvement in symptoms.