Background: HDM distribution varies between geographic areas and may be aff
ected by housing characteristics. We quantified Der p 1 and Der f 1 and ass
essed the relationships between their levels and housing characteristics in
homes of nonallergic subjects.
Methods: Der f 1 and Der p 1 were measured by ELISA in dust samples from li
ving-room floors and mattresses of 44 homes of nonallergic subjects in Pavi
a. Information about household characteristics was obtained by questionnair
e.
Results: Der p 1 and Der f 1 concentrations (mu g/g dust, median) were 0.34
and 7.8 on mattresses, and 0.15 and 0.83 on living-room floors. Higher Der
f 1 levels on mattresses were associated with synthetic pillows (P < 0.05)
, and (only when expressed as mu g/m(2)) with bedding washing temperature o
f less than or equal to 60 degrees C (P < 0.05). Der f 1 levels were higher
on the living-room floors of homes located on lower (less than or equal to
first) floors (P < 0.05). Good correlations were found between Der p 1 and
Der f 1 expressed as mu g/g dust and mu g/m(2) on both mattresses and livi
ng-room floors.
Conclusions: In homes of nonallergic subjects in northern Italy, Der f 1 ex
ceeded the threshold for sensitization in a high proportion of mattress sam
ples.