House dust mite allergen levels in individual bedding components in New Zealand

Aims. House dust mite allergen (Der p 1) levels are high in New Zealand and bedding Der p 1 levels have been shown to be associated with the clinical severity of asthma. The aim of this study was to measure Der p I levels in synthetic and feather duvets and other individual bedding items, and to examine factors affecting these levels. Methods. Reservoir dust samples were collected and analysed for Der p 1 content by ELISA from 65 duvets, 81 pillows, and 65 mattresses of 34 children and 31 adults in 34 households. Results. Der p 1 geometric mean levels (95% confidence interval) were: 13.4 mug/g (9.5-18.9) in pillows; 29.4 mug/g (19.8-43.5) in duvets; and 53.8 mug/g (39.4-73.4) in mattresses. Synthetic pillows and duvets yielded significantly more Der p I than feather pillows and duvets (about 7-fold and 15-fold respectively). The presence of under-bedding resulted in significantly higher pillow and duvet Der p 1 levels. Mattresses >10 years old had significantly higher Der p 1 levels. Conclusions. Synthetic pillows and duvets contain higher levels of Der p I than feather pillows and duvets. Advise for house dust mite sensitized individuals to use synthetic bedding does not prevent house dust mite allergen exposure.