After two years, about 10 percent of the weight of your pillow consists of dust mite droppings…
Every week you lose about 14 grams of skin cells, a large part of which is in bed. In addition, your bed is a nice place for dust mites, dust mites thrive in warm, moist places. House mites can trigger an allergic reaction, especially in people who suffer from asthma, eczema or hay fever.
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Source:Refinery29