To paraphrase a famous sportscaster: You can’t stop dust mites; you can only hope to contain them. There is more truth in the statement than you would think. Dust mites don’t live very long anyway, but they are durable, reproduce rapidly, and are widely dispersed inside the average home. Containment via dust mite covers of mattresses, box springs and pillows is recommended as the best measure for combating dust mites, but you may still look for other weapons. Those that are lethal fall into these categories:
Dust mite sprays called acaricides.
Heat treatments, both wet and dry.
UV-C light treatments (effective on dust mite eggs only)
Each method has its positive and negative attributes concerning effectiveness, efficiency, safety, cost, and availability.
Dust mite-specific pesticides can be classified generally as either synthetic or natural. They also have one of two modes of action, but not both: They either kill mites outright, or they de-activate (denature) the mites’ allergens. Unfortunately, the drawbacks to the use of acaricides often outweigh their benefits. Treatments are recommended for carpets only, are fairly labor-intensive and time-consuming, and the long-term effectiveness varies considerably. All treatments eventually need to be repeated, which can result in discoloration of carpets and potential health effects on users over time.
“Steam cleaning” of carpets in the conventional sense has no effect on dust mites, even boosting their populations on occasion by elevating the moisture level of the carpet and the humidity of the household in general. However, high temperature steam cleaning (such as with the Ecovap produced by Ecosteam) can both kill mites and denature one of the worst of the dust mite allergens. One study showed a dramatic improvement in asthma symptoms for up to nine months following such a treatment. Dry treatments that slowly raise the air temperature in a room (or confined space where mattresses and rugs can be treated) to 140 F can have a similar effect. ThermaPure is one of the few companies providing this service, however, and it is not cheap.
Laundering bedding at a high temperature (water temp of at least 130 F) on a regular (weekly or every other week) is essential in reducing dust mite populations where a person has the highest exposure to their allergens.
Lamps and light wands that emit ultraviolet (UV) light at certain wavelengths lethal to dust mite eggs (apparently not the larvae, nymphs, or adult mites) have demonstrated some effect, but again the benefits are of limited duration. Further, the devices which generate the required UV-C wavelength do so with mercury, a toxic heavy metal. Human exposure to UV light in general is not recommended, and operators of these devices must at minimum wear protective, UV-impermeable eyewear. Since exposure of the mite eggs to the UV-C for at least five seconds is required to kill them, the device must be slowly and/or repeatedly moved over the surface being treated (carpets, rugs, blankets, draperies).