Why does heat & humidity affect my asthma?

As long ago as 1662 it was recognised that the inhalation of dust particles in the air could lead to symptoms now recognised as typical of an allergic reaction. John Baptista van Helmost, a Flemish doctor, wrote of his patients: 'as oft as any place is swept or the wind doth otherwise stir up dust, he presently falls down, being almost choked'.

It was not, however, until the 1960's that it became appreciated that the major factor in dust that people were allergic to was the house dust mite. House dust mite levels can be controlled, to a degree, by controlling humidity levels in the home that provide a suitable environment for them to spread.

Dust mites hate dry conditions. They need moisture to breed and be active. If you can reduce the relative humidity in your home by using a dehumidifier then dust mite generation will also reduce.