7 Most Common and Sometimes Hidden Allergens in Your Home

Allergic diseases are among the fastest growing chronic conditions in Australia with 20% of the population affected by allergies like asthma, eczema, hayfever and food intolerances (Australian Society of Clinical Immunology & Allergy 2014).

Allergies can significantly impact the quality of life and some are life-threatening. While many factors (indoor lifestyle, inadequate diet, ambient air pollution, conventional farming practices and overuse of antibiotic drugs) are implicated in the development of allergic diseases, some of the most common asthma and eczema triggers are found right in our homes and backyards:

1. House dust mite (HDM)

HDM is one of the more prevalent indoor allergens which has been shown to be a leading cause of asthma and hay fever worldwide (Rao & Bhat 2015). Many people with a HDM allergy are often diagnosed with asthma, hay fever, perennial sinusitis and eczema (Bijlsma 2018). Apart from development and exacerbation of asthma (IOM 2000; Calderon et al 2015), reported symptoms of exposure to HDM allergen also include itchy, watery eyes; sneezing; itchy, runny or blocked nose; dry persistent cough; wheezing and eczema (Demoly et al 2016; Poza Guedes et al 2016).

Dust and dust mites are present in every home. They require moisture, warmth (above 25 degrees Celcius), and food (human and pet dander, cellulose from textile fibres, pollens and microbes) (Bijlsma 2018). High levels are typically found in bedding, carpets, soft furnishings, fabric window dressings and soft toys. Their numbers peak around mid/ late-summer when average humidity is high and monthly average temperatures exceed 23 degrees Celsius (Demoly et al 2016; Crisafulli et al 2007). Mattresses, where we sweat and shed skin cells and doonas are especially notorious for high levels of HDM, especially old ones. Furthermore, HDMs will also be prevalent in those parts of the home where moisture occurs, often where humidity interacts with cold surfaces such as floor tiles or uninsulated floors (Bijlsma 2018).

2. Old carpets

Old carpets are likely to carry a heavy burden of dust, which may contain dust mites, dirt, pesticides, heavy metals and other toxins, all of which can significantly contribute to exacerbation of allergies and asthma (Chew et al 1998). The fibres and backing, chemical treatments, padding and glues all come with their own chemical consequences. Some types of carpeting use chemicals that have been associated with respiratory symptoms, eye irritation and rashes (Anderson 1995), as well as chemicals that can react with each other to produce formaldehyde, a known human carcinogen (IARC 2006). In addition, if previous tenants had pets who lived inside, the carpet as well as other areas might still be contaminated with pet urine and contain traces of pet allergens, which will outgas together with other microbial by-products released by growing fungi and bacteria. Together, these are commonly known as mVOCs (microbial volatile organic compounds) and have been associated with sneezing, runny or stuffy nose, itchy and water eyes, asthma, cough and eczema (IOM 2004). 

3. Pests

Cockroaches and rodents are often found in older homes because they are likely to have easier means of ingress and can become a source of water, food and shelter for pests. Most pests produce pest allergen, exposure to which has been linked to asthma, hayfever and eczema (Matsui et al 2006; Kanchongkittiphon et al 2015; Portnoy et al 2013; Ahluwalia et al 2013). 
Check out my Avoiding Pesticides and Keeping your Home Pest-Free Naturally blog for some safe and natural alternatives for pest control, that you can start doing right away.

4. Old fireplaces and unflued gas heaters

If you have an old fireplace in your home, do not operate it until it has been checked, cleaned and serviced by a licensed professional. Unmaintained fireplaces can be blocked, leaking or have damaged/unlined 
chimneys which can back draft into a home and release harmful combustion gases and sometimes fatal concentrations of carbon monoxide. Open wood-burning fireplaces release a complex mixture of gases, fine particles and cancer-causing chemicals including benzene, formaldehyde and polycyclic aromatic hydrocarbons (PAHs). Short-term exposures to these pollutants (hours or days) can aggravate lung disease, causing asthma attacks and acute bronchitis, and may also increase susceptibility to respiratory infections (US EPA 2017). Long-term exposures (months or years) have been associated with problems such as reduced lung function and the development of chronic bronchitis - and even premature death (US EPA 2017). Furthermore, unsealed fireplaces can also become potential moisture intrusion points, which can exacerbate mould issues.

Similarly, using an unflued gas heater can expose you and your family to higher levels of harmful air pollutants such as carbon monoxide, nitrogen dioxide, sulphur dioxide, carbon dioxide, radon and formaldehyde, all of which can have a detrimental impact on your health (NSW Government Health 2004) and are best avoided.

5. Plant pollen

Plant pollen is a common source of seasonal allergies like hayfever. Most of the pollen that cause allergies is produced by introduced northern hemisphere grasses (such as perennial rye grass), trees (exotic trees, which are planted for their autumn colours), weeds and plants that have small inconspicuous flowers (ASCIA 2017), all of which could grow in your backyard.

Grass pollens are the most frequent cause of hayfever and are generally released in the early morning in summer, and descend in the evening, which is when symptoms may become more pronounced. October and November (when Westerly winds predominate) are the peak months for grass pollen in Sydney.

Sydney Pollen Count and Forecast provides daily pollen counts, which you can also trace by downloading a pollen app. Contact your council for a list of grass, weed and tree pollens in your area. In addition, refer to The low allergy garden: how to avoid garden allergens by Asthma Foundation Victoria for a list of plants and trees that should be avoided in your garden in order to reduce your family’s exposure to plant allergens. Oher suggestions include:

  • Don’t have a compost heap. 

  • Avoid planting strongly perfumed plants, especially near the windows of the house. 

  • Keep lawns well mown to reduce the amount of flowering and pollen. 

  • Remove weeds, particularly asthma weed, from your garden. 

  • Avoid wind-pollinated plants and male deciduous trees. 

6. Mould

Almost all modern homes experience at least minor, and sometimes serious, water damage during their life span. Excess moisture in buildings becomes a critical factor for mould (fungal) proliferation. Mould does not need a lot of moisture to grow. A little condensation, in a bathroom or around a window sill, for example, can be enough. Common sources of water or moisture include roof leaks, condensation due to high humidity or cold spots in a building, slow leaks in plumbing fixtures, poor drainage around the site, blocked/damaged gutters and downpipes, rising damp, sprinkler systems, and floods. There are also many causes that are not so obvious to the untrained eye, such as poor ventilation, inadequate insulation, contaminated air-conditioning system, close proximity to compost and still water, lack of natural light, clutter, lack of external exhausts in wet areas, poor building practices and inappropriate building materials.

Water-damaged homes typically not only have mould and their by-products, but also elevated bacterial loads, microbial chemicals, particulates, douse dust mites as well as pests like cockroaches, rodents and termites as well as chemicals released by damp building materials, all of which in their own accord, can contribute to adverse health effects (Bijlsma 2018).

People living in water-damaged homes have been known to experience a variety of allergic and inflammatory health effects including skin irritations, eczema and lung problems like asthma, bronchitis, cold and flu-like symptoms, hay fever, pneumonia (Antova et al 2008; Fisk et al 2010; Mendell et al 2011). National Asthma Council Australia recognises mould as one of the most common allergic triggers of asthma (National Asthma Council Australia 2017). The main cause of concern for health impacts in buildings is through the inhalation of mould and its by-products, although dermal symptoms may be caused by skin contact to mould.

Mould spores may remain dormant for many years, they will thrive when they are given food and water. As most conventional building materials and furnishings are the ideal ‘fast food’ for fungi, the key to addressing mould related problems is to locate the source of moisture and remove it (Bijlsma 2018). Within 48 hours of moisture being present, the spores, which are already sitting on all surfaces, will begin to germinate (Bijlsma 2018).

7. Chemical Irritants

While there are thousands of chemicals that are known to trigger allergic diseases such as eczema, asthma and hayfever, cleaning and personal care products are notorious culprits. Many conventional household cleaning products contain hundreds of chemicals (formaldehyde, nitrosamines, dioxins) that are associated with significant adverse health effects ranging from asthma and allergies to reproductive and developmental toxicity (Environmental Working Group 2016).

Fragrances that are found in air fresheners, perfume, aftershave, candles, many cleaning and personal care products, incense, reed diffusers and toilet deodoriser blocks can contain hundreds of petrochemicals including known carcinogens, hormone disrupting chemicals and asthmagens. Fragrances are collectively considered among the top five allergens in the world (de Groot 1997; Jansson 2001). These pollutants can be absorbed by surfaces inside the home and be re-released into the air at a later stage. They can also react with ozone (common ambient and indoor air pollutant) to form secondary pollutants such as formaldehyde, a known skin and lung irritant, and a carcinogen (Steinemann 2016; Council NR 2011).

Artificial fragrances in laundry products and fabric softeners are of particular concern as they are readily absorbed into the body via skin and lungs. Apart from causing contact dermatitis with symptoms such as itching, redness and swelling, fragrances enter the blood circulation where they can damage the reproductive organs and immune system (Magnano et al 2009; EPA 2000; NTP 2016).

Antibacterials, disinfectants & preservatives (ammonia, bleach, triclosan) can be found in a massive array of consumer products: everything from hand soaps and sanitisers to cutting boards, food storage containers, luggage, personal care products like toothpaste and deodorant, textiles like clothing, bed sheets and towels. A lot of these chemicals are known eye, skin and lung irritants that may cause asthma and allergies, and some are hormone disrupting chemicals linked to thyroid and reproductive issues (Savage et al 2014; Magnano et al 2009; NTP 2016). Antibacterials in hand soaps can react with chlorine present in municipal tap water and form small clouds of chloroform gas, a chemical that affects the central nervous system, liver and kidneys (Fiss, Rule & Vikesland 2007).

When it comes to personal care products including perfumes, deodorants, shampoos, conditioners, skin care products, body washes and creams, aftershaves and antiperspirants, many of these are skin irritants and contain phthalates and non-phenols (hormone disrupting chemicals linked to reproductive and neurodevelopmental disorders), preservatives such as formaldehyde, parabens and boric acid (skin irritants, hormone disruptors and some are carcinogens), polycyclic aromatic hydrocarbons (linked to cancer, skin irritations and allergies), lead (neurotoxin), polyethylene glycols (carcinogen and developmental toxicant), aluminium compounds (found in antiperspirants and can mimic estrogen, which promotes growth of breast cancer cells) to name a few (EWG 2007; UNECE 2004; Allam 2016).

Surprisingly, many of these toxic chemicals are found in ‘natural’ products as well. A report by the Organic Consumers Association (OCA) found a toxic chemical - carcinogen known as 1,4-dioxane in over 40% products that call themselves ‘natural’ (OCA 2008). Many soaps (bars or liquid castile) have a high pH of 10 that can damage and dry out the skin aggravating allergic reactions such as eczema (ASCIA 2015).

So now, that you are aware of what and where potential asthma and allergy triggers are in your home, register to download our free 'Healthy Home Healthy Child' e-book with 10 most effective ways that will help you reduce your family’s exposure to allergens inside your home and create an environment that will support your family's long-term vibrant health.

Healthier Home one step at a time!


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