Are you sleeping in a bed full of faeces?
The World Health Organisation estimates that we spend up to 90% of our time indoors. As winter draws in and lockdowns continue in some parts of the world, this is only set to increase. Dust mite season is upon us and as we spend more time indoors, do we really know what’s lurking in our homes?
8 October 2020
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.
In fact, dust mite allergens are the most relevant inducers of allergic diseases worldwide, and extensive exposure in early childhood to indoor allergens, including house dust mites has been associated with asthma.
From May-October, dust mite breeding season takes place over which time the female of the species lays between 60-100 eggs. This means the numbers of dust mites in your home increase and the concentration of allergenic material in your home can be high. But even though mites die off in the winter, the allergenic material they produce – including faeces, body parts and saliva – is left behind.
“As the weather cools, we tend to spend more of our time indoors and ventilate our homes less frequently,” says Gem McLuckie, Lead Research Scientist in Microbiology at Dyson. What’s more, dust is light enough to become airborne. When we turn our heating systems on, convectional currents can move dust mite faeces and allergen around the air in our home which is why many dust mite allergy sufferers may find that their symptoms worsen in the winter months.
“The start of autumn is a perfect time to reset the dust levels in your home, removing dust and allergenic material so as to support your wellbeing. In fact, Autumn cleaning is just as important as Spring cleaning,” says Gem McLuckie.
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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, 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.
“Wherever you spend the most time and shed the most skin, that’s where you’re most likely to find dust mites,” says Gem McLuckie, “and we spend 1/3 of our lives in our beds. In fact, most of us are probably sleeping in a bed full of dust mite faeces.”
Indeed, there can be millions of dust mites in a single mattress. A 2003 study found detectable dust mite allergen in the beds of about 84% of surveyed American home and in Europe, detectable allergen was found in 68% of homes.
“Its 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,” adds Gem.
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. That means that areas where we sweat, breathe and share our body heat are perfect homes for mites. 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.
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Gem McLuckie, Dyson Microbiologist
Gem works as a Lead Research Scientist in Dyson's RDD facilities in Malmesbury, UK
“Few mites can survive in humidity levels less than 45%, 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, particularly in winter when we tend to ventilate our homes less often."
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Well-being Impact
"Dust mites are not dangerous,” assures Gem. “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.”
Many of us may be familiar with a runny nose, watery eyes and an itchy throat after moving old dusty clothes, which would constitute a mild reaction to dust mite allergens. But the impact can be more serious in 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.
So, what can you do to battle dust mite season in your home?
Dyson Microbiologist Advice
“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,” explains Gem. “It also means we know a thing or two about the conditions in which they thrive!”
1. Starve your dust mites – reducing the amount of skin cell debris in your home minimises the primary food source of dust mites, inhibitng them from reproducing exponentially during 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. 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!
Footnotes
Klepeis NE, Nelson WC, Ott WR, et al. (2001), The National Human Activity Pattern Survey (NHAPS): a resource for assessing exposure to environmental pollutants. J Expo Anal Environ Epidemiol;11:231-52.
Sánchez-Borges, M., Fernandez-Caldas, E., Thomas, W.R. et al. International consensus (ICON) on clinical consequences of mite hypersensitivity, a global problem (2007), World Allergy Organ J 10, 14. https://doi.org/10.1186/s40413-017-0145-4
Sarwar, Muhammad (2020), House Dust Mites: Ecology, Biology, Prevalence, Epidemiology and Elimination, IntechOpen. Available at : https://www.intechopen.com/books/parasitology-and-microbiology-research/house-dust-mites-ecology-biology-prevalence-epidemiology-and-elimination.
Sánchez-Borges, M., Fernandez-Caldas, E., Thomas, W.R. et al. (2017), International consensus (ICON) on: clinical consequences of mite hypersensitivity, a global problem. World Allergy Organ Journal; 10, 14.
Sporik, Richard and Holgate, Stephen T. and Platts-Mills, Thomas A.E. and Cogswell, Jeremy J. (1990), ‘Exposure to House-Dust Mite Allergen (Der p I) and the Development of Asthma in Childhood’, New England Journal of Medicine, 323(8): 502-507. Available at: https://www.nejm.org/doi/full/10.1056/nejm199008233230802.
In the last five weeks of her life.
Wechsler, Charles J et al. (2011) ‘Squalene and cholesterol in dust from Danish homes and daycare centers’, Environmental Science & Technology, 45 (9) 3872-3879.
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.
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
Arbes, Samuel J.; Cohn, Richard D.; Yin, Ming; Muilenberg, Michael L.; Burge, Harriet A.; Friedman, Warren; Zeldin, Darryl C. (2003-02-01). "House dust mite allergen in US beds: Results from the first national survey of lead and allergens in housing". Journal of Allergy and Clinical Immunology. 111 (2): 408–414.
Luczynska, Christina; Svanes, Cecilie; Dahlman-Hoglund, Anna; Ponzio, Michela; Villani, Simona; Soon, Argo; Olivieri, Mario; Chinn, Susan; Sunyer, Jordi (2006-09-01). "Distribution and determinants of house dust mite allergens in Europe: The European Community Respiratory Health Survey II". Journal of Allergy and Clinical Immunology. 118 (3): 682–690.
American College of Allergy, Asthma and Immonology (2020) Dust Allergy. Available at: https://acaai.org/allergies/types/dust-allergy
22 degrees Celsius. Optimal relative humidity levels will depend on temperature.
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Isabel Matthews
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