Dust mites are microscopic arachnids that feed on shed skin cells. They cannot be seen without a microscope and do not bite. They live in warm, humid environments ? particularly in mattresses, pillows, quilts, carpets, and upholstered furniture. A single mattress can harbour large numbers of mites. ASCIA notes they are one of the most significant indoor allergen sources in Australian homes, particularly in coastal regions where humidity is high.

Dust mites are invisible to the naked eye, so their presence is typically inferred from patterns rather than direct observation. Indicators can include reactions that seem worse in the morning after time in bed, or when making or changing bedding. Dust mites are present in almost all Australian homes ? their presence should be assumed rather than confirmed. The more relevant question is how to reduce allergen levels to the lowest practical level.

Complete elimination of dust mites from a home is not considered achievable ? they are present in virtually all Australian households. The evidence-supported goal is reducing allergen levels to the lowest practical level. The most effective measures are encasements on mattresses, pillows and quilts, washing bedding at 60 degrees Celsius or above weekly, maintaining indoor humidity below 50%, and HEPA vacuuming. Combining these measures consistently produces the most significant allergen reduction.

The most evidence-supported first step is encasing the mattress in a tightly-woven dust mite encasement with a pore size small enough to block dust mite allergen particles. This creates a physical barrier between you and the allergens present in the mattress. ASCIA recommends encasements as a primary allergen-reduction measure. Additional steps include vacuuming the mattress surface with a HEPA vacuum and maintaining bedroom humidity below 50%.

The National Asthma Council Australia and ASCIA both recommend washing bedding at 60 degrees Celsius or above to reduce dust mite allergens effectively. Cold washing alone is not sufficient. Weekly washing at the correct temperature is commonly recommended. If hot washing is not possible, products containing eucalyptus or tea tree oil formulated for cold-water washing may offer an alternative, though the evidence for these is less robust than for hot washing.

Exposing bedding and soft furnishings to direct sunlight for several hours can help reduce dust mite numbers ? dust mites are sensitive to desiccation and UV exposure. However, sunlight alone does not remove the allergen already present in fabrics. For full allergen reduction, sun exposure is most effective when combined with washing at 60 degrees Celsius and hot tumble drying. In Australia's climate, regular sun exposure of bedding is a practical and low-cost complementary measure.

Air purifiers with HEPA filtration can capture dust mite allergen particles that become airborne ? for example when bedding is disturbed. However, because most dust mite allergen is found in mattresses, pillows, and carpets rather than suspended in the air, air purifiers offer limited benefit as a standalone measure. They are most useful as a complementary step alongside encasements and regular hot washing, not as a primary intervention.

Dust mites absorb moisture from the air rather than drinking water, making indoor humidity the most critical environmental factor in controlling their numbers. Research consistently shows that keeping indoor relative humidity below 50% significantly reduces dust mite survival and reproduction. ASCIA recommends targeting below 50%, particularly in the bedroom. A dehumidifier or hygrometer can help monitor and maintain this level, especially in humid coastal Australian climates.

Tightly-woven mattress encasements are among the most consistently evidence-supported physical measures for reducing exposure to dust mite allergens during sleep. They work by blocking allergen particles from passing through to the sleeper. ASCIA recommends them as a primary measure for managing dust mite allergen exposure at home. The key factors are pore size ? covers need a pore size small enough to block allergen particles ? and a fully sealed zip enclosing the entire mattress.

A regular mattress protector is designed primarily to protect against liquid damage and physical wear. A dust mite encasement is made from fabric with a pore size small enough to block dust mite allergen particles, and fully encases the mattress with a sealed zipper on all sides. The two products serve different purposes. If allergen reduction is the goal, a dust mite encasement is the appropriate choice ? a standard mattress protector does not provide the same allergen barrier.

Allergen-neutralising sprays can help reduce dust mite allergen levels on surfaces where washing or encasing is not practical ? such as sofas, carpets, and soft toys. They work by denaturing allergen proteins rather than killing mites. The evidence for sprays is more limited than for encasements and hot washing. Sprays are best used as a complementary measure rather than a primary one. Always follow product instructions and ensure the area is well ventilated during application.