Dust allergy - or what to?
Dust allergy is the nightmare of the 21st century. People sensitised to house dust allergens account for more than half of those suffering from allergic rhinitis (ANN). This means that at least 6.5 million Poles are chronically ill due to dust [7]. At least, because it is not only associated with ANN, but also with asthma and other allergic diseases.
Dust is a mixture of various substances (organic and inorganic) and also a habitat for many micro-organisms. It contains, among others, sand grains and other soil particles, coal dust, fragments of exfoliated epidermis, hair and dander, clothing fibres, pollen, insects and mites (and their secretions). It is these dust elements that are the source of indoor allergens [8].
House dust mite
The main cause of dust allergies is house dust mites, which affect as much as 25% of the Polish population [1, 7]. Those allergic to dust mites experience symptoms that worsen after contact with dust, especially in the morning and during nighttime rest [2]. It is precisely in warm and humid enclosed spaces where house dust mites thrive best.
These tiny organisms are not visible to the naked eye. They feed on shed skin, both human and animal. Therefore, they primarily inhabit beds, where we leave this skin residue daily (about 2-3 grams) [7]. Their allergens are found in pillows, mattresses, carpets, and upholstered furniture. Dust mites become airborne during vacuuming, walking on carpets, and making the bed. Due to their microscopic size, they are difficult to remove during regular cleaning [1].
In addition to dust allergies and allergic rhinitis, dust mites can also trigger asthma and exacerbate eczema [1]. About 80% of patients with atopic asthma have positive skin tests for house dust mite allergens [7]. Dust mites are also responsible for severe cases of atopic dermatitis (eczema).
Cockroaches and pruses
Unwanted roommates responsible for dust allergies include insects, especially cockroaches and dust mites. They exhibit increased activity at night and can easily enter the apartment, for example, through garbage chutes [6]. Their allergens are most commonly found in kitchens and pantries, where cockroaches are often present due to the presence of food waste [4, 5]. However, they can also be found in bedding, furniture, and on the floors of other rooms [4].
In dust, remnants of cockroaches, fragments of their exoskeletons, as well as feces and eggs accumulate [5]. Cockroach proteins are also detected in some food products, such as flour [5].
Allergy to cockroaches is considered a significant risk factor for asthma [4, 5]. Studies conducted both in the USA and in Poland have found allergies to these insects in 25% of children with asthma. Furthermore, it has been shown that severe asthma occurred more frequently in these individuals than in those allergic to other allergens [5].
Importantly, due to the similarity of allergens (tropomyosin) between cockroaches, dust mites, and even shrimp, cross-reactions may occur among them [5].
Mould spores
Dust allergies can also be triggered by mould spores, which thrive in the damp environment of waterlogged houses and flats. They reach their highest concentration in autumn and live not only in the air, but also in dust. Analysis of the composition of dust from hoover bags carried out in the USA showed the presence of moulds such as Chaetomium globosum, Aspergillus fumigatus and Eurotium [9]. In Poland, inhalatory allergies are mainly caused by fungi of the genera Alternaria and Cladosporium, as well as Penicillium and Aspergillus [10].
Due to their size, fungal spores easily enter the lower respiratory tract. The volume of one grain of grass pollen corresponds to as many as 3,000 Aspergillus fumigatus spores [10]. And moulds living in house dust can account for between 5 and up to 20% of its total weight.
Already many years ago, it was estimated that 25% of Polish dwellings (inhabited by approx. 8 million people) are contaminated with mycotoxins and mould allergens [11].
Pollen of trees, grasses and weeds
Dust allergy can also be linked to the presence of pollen from wind-pollinated plants in the domestic environment. Due to climate change, the pollen season is getting longer every year. In Poland, it starts before spring (with hazel pollen) and lasts until autumn. Pollen falls indoors through open windows and is carried on clothes and shoes. They can settle on floors and furniture. In addition, it is worth remembering that pollen also affects potted plants that serve as decorations in our homes. Some of these plants also secrete allergenic sap, which collects in dust [13].
Pet and rodent allergens
Allergens present in house dust also include dander, as well as epidermal fragments and secretions from pets and rodents. Epidermis and secretions (such as urine and saliva) – contrary to popular belief – contain many more allergens than dander alone, which only transports them [15]. So what we take for a dust allergy may in fact mean that we are allergic to animal allergens. It is easy to be confused especially when we do not keep a pet at home, but are visited by, for example, mice or other rodents.
Animal allergens are ubiquitous – they are even found in dwellings that have never had animals in them, and even in places such as hospitals [14]. They enter passively carried by people, if only on clothing, because they are very sticky. In homes without dogs, for example, the concentration of dog allergens is about 10 µg/g of dust (average 3 µg/g) [15].
However, dog allergies are much rarer than cat allergies. Studies show that a cat produces enough allergens in 10 seconds for an allergic person to have an asthma attack. And the particles of these allergens are 10 times smaller than mite allergens [14].
4-10% of people are allergic to dog or cat allergens, but among atopic people the proportion of allergic people is three times higher. More than half do not keep pets in the home [15].
Chemicals and heavy metals
Various compounds and chemical substances, including heavy metals, are also increasingly found in house dust. These are dangerous not because of the risk of an allergic reaction (although a dust allergy can also occur because of them). They are dangerous because of the risk of poisoning, as well as long-term health effects. This risk particularly affects young children [8].
The presence of heavy metals in flats and houses is mainly influenced by their furnishings, but also by their close presence to busy streets. A high concentration of zinc was found in dust samples taken from Lublin flats. Its source is mainly abrading vehicle tyres. Lead and cadmium were also detected, which may come from furniture and fabrics made of plastic [8].
How to recognise and treat a dust allergy?
Dust allergy is not a medical diagnosis, but a colloquial term. In order to identify its true cause, it is necessary to undergo diagnostics to determine which particles in dust the allergic person reacts to. The treatment path will also depend on this. And treatment is worthwhile, because an untreated allergy may lead, for example, to developing asthma.
Two methods are used to diagnose inhalant allergies:
- point skin tests,
- serological tests (from blood) detecting allergen-specific IgE antibodies.
Standard management consists of symptom relief (e.g. with antihistamines and topical corticosteroids) [16]. The only causal treatment option is immunotherapy, commonly known as desensitisation.This allows the patient to acquire tolerance to the allergen involved.
Aleksandra Lipiec
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translation: Julia Majsiak
