Are you sleeping in a bed full of dust mites?

Dust mite faeces are one of the main sources of allergens in household dust while mite allergens are a key inducer of allergic diseases worldwide.1 Dyson analyses New Zealand household dust to reveal what’s lurking in our homes and provide whole-house cleaning solutions.

November 2020

As the summer months approach and humidity levels increase, we spend more time moving between indoors and outdoors increasing the diversity of the microbial landscape of the dust in our homes. Dust mites are mostly found in homes with higher humidity levels and constant warm temperatures, so with more than one in five New Zealand homes damp some or all the time,2 dust mites are a common problem for Kiwis.

The Results

Dyson recently collected and analysed dust samples from real homes within New Zealand. In a home with a young child and pet dog, researchers found a strong concentration of dust mites per gram of dust from the mattress. In the same dust samples, researchers found high amounts of dander and pet and human hair, and other particles including bismuth oxychloride (found in cosmetics and hairsprays) and barium sulfate (found in plastics, paint and varnish). From the same home, researchers found high amounts of mould and bacteria, including Penicillum sp., a genus of fungi most commonly found in soil, rotting fruit, and decaying plant debris.

In another home with a pet dog, dust mites were found in samples from the mattress and floors, along with high amounts of pet and human hair, pet and human dander, ash and soot, and pollen. Other notable particulates included steel (from appliances, utensils etc), potassium chloride (found in fertiliser, food additives), and iron oxide (possible steel, rust).

Letitia Harding, Chief Executive of the Asthma Respiratory Foundation NZ, acknowledges that the conditions in which dust mites thrive lend themselves to Kiwi homes. “House dust mites thrive in warm, damp and dark conditions, particularly where humidity levels are around 70 per cent and temperatures rise above 25 degrees Celsius. The conditions mean that most of New Zealand, and Auckland in particular, are a perfect environment for dust mites to flourish.”

“In addition to the climate, areas at home where we sweat, breathe and share our body heat are perfect homes for mites. Sofas, mattresses, pet beds, curtains and other soft furnishings are fertile ground for dust mites, particularly in their breeding season where they take up residence and feed on pet dander (flakes of skin in an animal's fur or hair),” adds Letitia.

Dust Mite Season

Lead Research Scientist in Microbiology at Dyson, Gem McLuckie, says, “At Dyson, we farm our own dust mites so that we can collect their faeces. This means we can learn more about dust mite allergen and understand how our vacuums can best remove it from your home. It also means we know a thing or two about the conditions in which they thrive.”

From December to May, dust mite breeding season takes place over which time the female of the species lays between 60-100 eggs.3 This means the numbers of dust mites in your home increases and the concentration of allergenic material in your home can be high.

Gem explains: “What’s more, over the festive season, we tend to invite more people into our homes. The more people we have indoors, the more dead skin cells are deposited around our home – the primary food source of dust mites. That’s why spring is such an important time to deep clean your home. Removing excess skin flakes from your domestic space limits the food source on offer for dust mites, which means that their rate of reproduction is inhibited during the dust mite season”.

"Dust mites themselves are not dangerous,” assures Gem McLuckie. “The harmful allergen they create comes from the proteins present in their faecal pellets and body fragments. And that can have a considerable wellbeing impact for those living in homes where dust mite colonies are present.”

The impact of dust can be more serious to certain individuals. Positive tests for dust mite allergies are extremely common among people with asthma, types of dermatitis and frequent sinus infections. Studies also suggest that exposure to high levels of dust mites, especially early in life, increases your risk of developing a mite allergy and asthma too.4

What are Dust Mites?

House dust mites are microscopic arachnids that can be found in homes all around the world. Their average lifecycle is 65-100 days and during that time they will produce approximately 2,000 faecal pellets and secrete even more proteins through their saliva – both of which can trigger allergies and impact your wellbeing.5 In fact, dust mite allergens are the most relevant inducers of allergic diseases worldwide,6 and extensive exposure in early childhood to indoor allergens, including house dust mites has been associated with asthma.7

Skin Scavengers

Dust mites primarily feed on dander or dead skin cells shed by humans and animals. On average, humans shed 2g of skin per day,8 and even more at night where friction from bedding causes dead cells to shed. They can also get the nutrients they need from other household debris, like fish food, fungi and food crumbs.9

Gem McLuckie says, “Wherever you spend the most time and shed the most skin, that’s where you’re most likely to find dust mites, and we spend one third of our lives in our beds. In fact, most of us are probably sleeping in a bed full of dust mite faeces. It's also common to find more mites in the beds and bedding of people who suffer from dry skin, as their discarded skin cells have reduced lipid content, which are dust mites’ favourite meal.”

Indeed, there can be millions of dust mites in a single mattress.10

House dust mites thrive in warm, damp and dark conditions, particularly where humidity levels are around 70 per cent and temperatures rise above 25 degrees Celsius.11 That means that areas where we sweat, breathe and share our body heat are perfect homes for mites, like sofas, mattresses, pet beds and other soft furnishings are fertile ground for dust mites, particularly in their breeding season. But there are other daily tasks that can have an impact too.

“Few mites can survive in humidity levels less than 45 per cent, but even raising the humidity levels for an hour and a half a day can enable house dust mites to survive. Cooking a meal or having a hot shower can easily keep humidity levels high in your home.”

So, what can you do to battle the dust mite season in your home?

Dyson Microbiologist Advice

1. Starve your dust mites: reducing the amount of skin cell debris in your home minimises the primary food source of dust mites, inhibiting them from reproducing exponentially during the dust mite season. Vacuum your mattress on both sides with a machine with an advanced filtration system, as well as your sofa and other upholstery.

2. Manage humidity levels: dust mites hydrate themselves by absorbing water from the air, so keeping relative humidity levels below 45 per cent at room temperature will kill most of them off.12 Air out bedding and blankets frequently, as well as ventilating your home by opening the window or using a HEPA-filtered air purifier. Don’t forget to use the extractor fan after showering or while cooking too, as even raising the humidity levels for an hour and a half a day can enable house dust mites to survive.

3. Control the temperature: dust mites thrive at temperatures of 25 degrees Celsius, so ensure you vacuum warmer areas in your home frequently to control levels of dust mites, like pet baskets, sofas or mattresses. Washing bedding or other soft furnishing at 60-90 degrees Celsius will break up allergens too.

4. Top tips: don’t forget that dust mites and their faeces are microscopic. If you can see dust in your home, dust mites may already be thriving!

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[1] Sarwar M (29 April 2020), House Dust Mites : Ecology, Biology, Prevalence, Epidemiology and Elimination, Parasitology and Microbiology Research.
[2] RNZ (2019), NZ’s damp housing: 318,000 homes affected, 29 October 2019.
[3] In the last five weeks of her life.
[4] American College of Allergy, Asthma and Immunology (2020) Dust Allergy. Available at: https://acaai.org/allergies/types/dust-allergy
[5] Wechsler, Charles J et al. (2011) ‘Squalene and cholesterol in dust from Danish homes and daycare centers’, Environmental Science & Technology, 45 (9) 3872-3879.
[6] Sharma, D., Dutta, B. K., & Singh, A. B. (2011). Dust mites population in indoor houses of suspected allergic patients of South Assam, India. ISRN allergy, 576849. https://doi.org/10.5402/2011/576849
[7]Asthma and Allergy Foundation of America (2015) Dust Mite Allergy. Available at: https://www.aafa.org/dust-mite-allergy/
[8] Sarwar, Muhammad (2020), House Dust Mites: Ecology, Biology, Prevalence, Epidemiology and Elimination, IntechOpen.
[9] Wechsler, Charles J et al. (2011) ‘Squalene and cholesterol in dust from Danish homes and daycare centers’, Environmental Science & Technology, 45 (9) 3872-3879.
[10] Platts-Mills, T. A. E., de Weck, A. L., Aalberse, R. C., Bessot, J. C., Bjorksten, B., Bischoff, E., Bousquet, J., Van Bronswijk, J. E. M. H., ChannaBasavanna, G. P., Chapman, M., Colloff, M., Goldstein, R. A., Guerin, B., Hart, B., Hong, C. S., Ito, K., Jorde, W., Korsgaard, J., Le Mao, J., Wen, T. (1989). Dust mite allergens and asthma-A worldwide problem. The Journal of allergy and clinical immunology, 83(2 PART 1), 416-427.
[11] Asthma and Allergy Foundation of America (2015) Dust Mite Allergy. Available at: https://www.aafa.org/dust-mite-allergy/
[12] 22 degrees Celsius. Optimal relative humidity levels will depend on temperature.