The psychrometric control of house dust mites: a pilot study

Abstract

This paper describes a pilot intervention study on the effectiveness of house dust mite allergen avoidance for 12 asthmatic children (two being controls). In addition to mite allergen removal, the study included tailored advice aimed at reducing mite population growth via changes in moisture production, heating and ventilation habits. This paper focuses on the effects of this advice on household behaviour, hygrothermal conditions and mite populations. The efficacy of monitoring and modelling techniques is also discussed. The study highlighted a number of interrelated confounding factors which have to be addressed in future similar larger scale studies, but the results are promising with regards to the effectiveness of such studies. Practical application: This study suggests that in temperate climates tailored advice on moisture production, heating and ventilation habits can lead to valuable changes in hygrothermal conditions, which in turn can result in reduced mite populations. However, pre-existing adverse building conditions may hinder such changes, and the effectiveness of tailored advice and of hygrothermal modifications is often difficult to assess. It is therefore recommended that any similar larger intervention study measures ventilation rates and adequately controls for a number of confounding variables — including the effect of changes in outdoor conditions and of the removal of existing mite populations. In this respect, hygrothermal population models can play a very useful role in the assessment of study effectiveness.