Mattress covers designed as allergen barriers are a recommended intervention for individuals with dust mite allergies. These microscopic arachnids thrive in the warm, humid environment of a mattress. Exposure to their waste products can trigger symptoms like asthma and allergic rhinitis. Properly encasing the mattress and pillows is a primary strategy to minimize this exposure, sealing off the largest reservoir of dust mite allergens in the home.
What Exactly Are Dust Mites
Dust mites are tiny, eight-legged relatives of spiders, invisible to the naked eye, typically measuring between 0.2 and 0.3 millimeters in length. They do not bite or burrow into human skin. They flourish by feeding on the dead skin flakes that people and pets shed daily, making the bed a primary habitat due to the abundant food source, warmth, and humidity.
The trigger for allergic reactions is the protein found in the mite’s fecal matter and shed body parts. These microscopic waste particles easily become airborne when bedding is disturbed, and their inhalation leads to common allergic symptoms. A single dust mite can produce up to 2,000 allergenic waste particles in its short life, accumulating the allergen in soft furnishings.
The Science Behind Encasement Barriers
Allergen-impermeable covers create a physical barrier between the mattress contents and the sleeper. The cover’s effectiveness hinges on its pore size, which must be significantly smaller than the dust mite allergen particles. Fecal pellets, the main source of the allergen, average around 10 to 40 microns in size.
Medical research suggests that the fabric’s pore size must be less than 10 microns to effectively block the passage of allergens. Many high-quality encasements feature a pore size of 6 microns or less, ensuring that microscopic particles cannot escape the mattress. This tightly woven structure confines the existing mite population and their waste products inside the mattress, preventing them from reaching the air or skin.
The cover also cuts off the mites’ food supply, as shed human skin flakes cannot penetrate the barrier. This lack of food, combined with the barrier function, confirms that encasement products significantly reduce the concentration of allergens a person is exposed to during sleep. Studies consistently show that encasing the mattress, pillow, and box spring is one of the most effective ways to reduce allergen levels in the sleeping environment.
Essential Features When Buying a Cover
Selecting an effective encasement requires attention to the material structure and construction details. The two main types of fabric are membrane and non-membrane, each offering a different balance of comfort and barrier function. Membrane covers have a plastic-like layer, often polyurethane, laminated to the fabric, which provides a complete waterproof and allergen barrier.
Non-membrane covers are made from tightly woven microfiber or cotton, achieving the small pore size through a dense weave. This allows for better air and moisture permeability. While often more comfortable, consumers must verify the stated pore size, which should be below 10 microns, to ensure adequate protection. Regardless of the material, the cover must fully enclose the item and feature a fine-toothed zipper with a protective flap to prevent allergen leakage.
Covers must be purchased for all bedding components, including the mattress, pillows, and box spring, as mites can colonize any soft fabric. Look for products that carry the Asthma & Allergy Friendly Certification. This certification verifies that the product has been independently tested to meet strict standards for allergen blockage and material safety.
Other Strategies for Mite Reduction
While encasements are highly effective for the mattress, they are not a standalone solution for mite control. A comprehensive strategy includes regularly washing all removable bedding, such as sheets, pillowcases, and blankets. These items should be washed weekly in hot water at a temperature of at least 130°F (54°C) to kill the mites and remove accumulated allergens.
Controlling the environment’s humidity is another powerful tool, as mites struggle to survive in dry conditions. Maintaining the indoor relative humidity below 50% is a recommended measure, often achieved using air conditioning or dehumidifiers. Since mites absorb water directly from the air, keeping the humidity low inhibits their reproduction and survival.
Further reduction methods include using a vacuum cleaner equipped with a High-Efficiency Particulate Air (HEPA) filter, which captures tiny airborne mite allergens. Cleaning surfaces with a damp cloth or mop, rather than dry dusting, is advised to prevent allergens from being stirred up.