Pets produce dander (microscopic skin flakes that they shed), and the protein in it can cause severe allergic reactions for some people.
Pet dander is a little like dandruff flakes, only smaller; at around 2-3 microns in size it easily becomes airborne and can be inhaled.
Dander can cause allergic reactions for a long period and may persist for many months after the pet has left the house.
The origin of the allergens is in the pet’s urine, sweat and saliva. These excretions adhere to their skin, for example when they clean themselves, and become of the dander they shed.
Cat dander is the most commonly inhaled allergen after house dust mite and pollen. Other types of pet, such as dogs, mice and guinea pigs, may similarly cause allergic reactions.
Because they are so light, pet allergens are widely distributed in the air, remaining airborne for several hours before settling, only to be easily stirred up into the air again.
Clearly, the best way of avoiding pet dander is to not have a pet! However, many of us love our pets too much to do without them! In that case, there are various measures you can take to reduce your exposure, including controlling the pet’s access to certain rooms, and using an effective air purifier to neutralise the dander.
Pet allergies and your health
Pet allergies are known to play a role in:
People with a tendency to allergy (known as atopy), should avoid owning pets if possible. Unfortunately, some people who don’t initially exhibit allergic reactions, can nevertheless develop symptoms after continued exposure.
Why pet dander causes an allergic reaction
Allergens usually enter the respiratory system through the nose. Mast cells in the airways release mediators, which trigger the allergy attack. This attack is an overreaction of the body’s immune system to the invading allergens that have bonded with antibodies. Mast cells are one of the human body’s principal defences against allergens and are found in connective tissue and mucous membranes. One of its biological functions is innate immunity including involvement in host defence mechanisms against parasitic infestations, tissue repair, etc.
Pet dander is very ‘sticky’ and can stay in your hair, clothes and other belongings for long periods of time. This is why you can still suffer symptoms when you are away from the pet causing those symptoms.
The major cat related allergens are found in the cat’s sweat and saliva and the major dog related allergen is found in its saliva.
What animals cause allergy problems?
A wide range of animals can cause allergic reactions including cats, dogs, birds, mice, rats, guinea pigs, rabbits, parrots and hamsters.
Male cats shed more allergen than females, and cats shed more allergen than dogs. Horses produce very powerful allergens and old mattresses stuffed with horsehair can produce symptoms. Snakes, lizards and other reptiles, and even insects, may shed dander-like skin particles into the air.
Perhaps the best pets for a pet allergy sufferer are fish, as they are not associated with allergy!
What about hypoallergenic dogs?
Avoiding pet allergens
Before turning to technological or other solutions, careful allergen avoidance / environmental allergen control is important. For example:
And don't forget - Are you sure pet allergen is really the cause of your allergy? It could be that house dust mite, mould or pollen is the real culprit. An allergy specialist will be able to offer an allergy test to pinpoint the true allergen.
Can an air cleaner help?
While numerous manufacturers of ‘air cleaners’ / ‘air filters’ claim to be able to clear pet dander from the air, they can only reduce, not eliminate, the problem, because:
House dust mites are one of the most potent and common domestic and workplace triggers of allergic reactions.
Dust mites are microscopic eight-legged creatures called arachnids and they are closely related to the spider and the tick. They are found in every home and their presence is not an indication of poor cleaning!
It is not the dust mite itself which is the allergen but enzymes (proteins) found in its droppings and decaying body. The whole droppings themselves are particles between 4 and 20 microns in size but may crumble into particles as small as 0.5 microns across.
House dust mites feed upon the skin scales naturally shed by humans and other animals which are found in house dust. Although their presence is harmful to people who become allergic to them, dust mites do not bite or spread diseases.
While usual household insecticides have no effect on dust mites, fortunately there are multiple ways to reduce exposure to dust mite allergens in your home.
Dust mite allergy
As with other allergens, dust mite allergens cause an ‘over-reaction’ of the immune system in an allergic person. In allergy sufferers Immunoglobulin E (IgE) antibodies present on the surface of mast cells trigger the release of histamine when allergens stick to these IgE antibodies. It is histamine that produces the characteristic symptoms of an allergic reaction.
Dust mites love homes
Dust mites love humidity
To survive, house dust mites absorb water from the air. When humidity is less than 50% they tend to dry out and die. They also prefer temperatures around 21°C (70°F).
It is thus crucial to get rid of damp in your home. Ventilate by opening windows, and check for condensation in the kitchen and bathrooms. If you live in a humid area, consider buying a dehumidifier but remember that very dry air can be uncomfortable especially if you suffer with sinus or respiratory conditions.
Getting rid of dust mites in your home
The fight is never ending - dust mites are everywhere and even if you can get rid of all of them in your home, new ones would still appear (they are carried into your home on people’s clothing, for instance). So, look for long-term solutions which will reduce your house dust mite burden.
These measures will create an environment that could seriously reduce the house dust mite burden in your home.
Anti-mite spray and powder
Regular use of an anti-mite dust spray or powder can be of help. An anti-mite spray can penetrate mite reservoirs in carpets, soft furnishings and mattresses and anti-mite dry powder carpet cleaner can help get rid of mites where they nest.
When choosing allergy cleaning products, be careful to use cleaning products with natural ingredients. Spraying a chemical, especially on a regular basis, can be a severe trigger for people suffering with allergies.
Dust mites are not the only allergen in house dust
Cockroaches are commonly found in crowded cities and in, for example, the southern United States. Certain proteins in cockroach feces and saliva also can be found in house dust. These proteins can cause allergic reactions or trigger asthma symptoms in some people, especially children. Cockroach allergens likely play a significant role in causing asthma in many inner-city populations.
Can an air cleaner help?
While numerous manufacturers of ‘air cleaners’ / ‘air filters’ claim to be able to clear dust mite allergens from the air, they can only reduce, not eliminate, the problem, because:
You can learn more about why traditional air cleaners don’t work well here and why Airora’s unique technology does work here.
Mould spores are a potent allergen that can trigger severe asthma and rhinitis symptoms and cause a broad range of respiratory conditions. It occurs both indoors and outdoors and the density of mould spores is normally much higher than that of Pollen.
Mould spores, sometimes also called fungal spores, are light and are therefore readily carried through the air of your home or office. This is because their diameter is between one and 100 microns, depending on species, with most being between 2 and 10 microns. Moulds come in a variety of colours: white, grey, orange, green, pink and black.
Your first step in keeping the mould count under control is to ensure that you tackle any damp areas. Another important step is to neutralise mould spores in the air and on surfaces, to prevent the mould from spreading.
Types of mould
When inhaled, tiny fungal spores, or sometimes pieces of fungi, may cause allergic rhinitis or trigger an asthma attack. Because they are so small, mould spores also can reach the lungs.
In a small number of people, symptoms of mould allergy may be brought on or worsened by eating certain foods such as cheeses processed with fungi. Occasionally, mushrooms, dried fruits, and foods containing yeast, soy sauce, or vinegar will produce allergy symptoms.
Mould spores can also cause Allergic Bronchopulmonary Aspergillosis (ABPA) which is an allergy to the spores of Aspergillus fumigatus. Around 5% of adults with asthma develop ABPA at some time during their lives.
Where do moulds grow?
Mould loves damp conditions, so you will tend to find it in places such as:
What is the best way of preventing indoor mould?
Keep your home or office well-ventilated and dry, and discourage the dispersal of mould spores:
A mixture of bleach and water, a mixture of white spirit and surgical spirit, or a specialised anti-fungal spray can be used to get rid of mould patches. Mould tends to reoccur, so you may well have to repeat your cleaning operations.
Can an air purifier help?
While numerous manufacturers of ‘air cleaners’ / ‘air filters’ claim to be able to clear mould spores from the air, they can only reduce, not eliminate, the problem, because:
Plants produce tiny—too tiny to see with the naked eye—round or oval pollen grains to reproduce. In some species, the plant uses the pollen from its own flowers to fertilise itself. Other types must be cross-pollinated. Cross-pollination means that for fertilisation to take place and seeds to form, pollen must be transferred from the flower of one plant to that of another of the same species. Insects do this job for certain flowering plants, while other plants rely on wind for transport.
Pollen grains contain potent allergens which can cause hay fever, asthma attacks and conjunctivitis. Clearly, as pollen comes from trees, grass and weeds, most exposure occurs outdoors. However, pollen will inevitably also find its way indoors, so those allergic to pollen also find themselves reacting to pollen indoors.
Pollen grains include proteins that cause the immune system in an allergic person to over-react (it is these proteins that an Airora hydroxyl cascade neutralises). Exposure to the allergen proteins triggers a release of histamine from mast cells, that in turn leads to symptoms of allergy like redness, sneezing, swelling and runny nose.
A skin prick test, where you are exposed to various pollen allergens, can be used to confirm whether you have a pollen related allergy. Pollen grains that cause allergies are typically between 10 and 40 microns (a micron is 1/1000 of a millimetre) in size but can also fragment into smaller particles of around one micron in size. Airborne pollen can travel a surprising distance, for example into the centre of cities, but in a still internal environment it can quite quickly fall onto a surface, only to re-enter the atmosphere when it is disturbed.
Pollen allergies and your health
Pollen can cause various allergic reactions, individuals may suffer from one or more of these.
Conjunctivitis is inflammation of the membranes lining the inside of the eyelids.
Tips for reducing exposure to pollens outdoors
Tips for reducing exposure to pollens outdoors
Season and time of day matters
One of the most obvious features of pollen allergy is its seasonal nature.
People have symptoms only when the pollen grains to which they are allergic are in the air. Each plant has a pollinating period that is more or less the same from year to year. Exactly when a plant starts to pollinate seems to depend on the relative length of night and day—and therefore on geographical location—rather than on the weather. On the other hand, weather conditions during pollination can affect the amount of pollen produced and distributed in a specific year. Thus, in the Northern Hemisphere, the farther north you go, the later the start of the pollinating period and the later the start of the allergy season.
For example, in the UK:
A pollen count, familiar to many people from local weather reports, is a measure of how much pollen is in the air. This count represents the concentration of all the pollen (or of one particular type) in the air in a certain area at a specific time. It is shown in grains of pollen per square meter of air collected over 24 hours.
Pollen counts tend to be the highest early in the morning on warm, dry, breezy days and lowest during chilly, wet periods. Although the pollen count is an approximate measure that changes, it is useful as a general guide for when it may be wise to stay indoors and avoid contact with the pollen.
Night-time ‘pollen showers’
On a warm day, when there is naturally a lot more pollen around, warm air rises up from ground level, taking pollen up with it. When the air cools, after dusk, the pollen that has risen during the day drifts back towards the ground. This effect creates what is sometimes termed a 'pollen shower' and explains why, in the middle of a hot night, you may get an allergic attack when you are in bed, particularly if you have the bedroom windows open.
Types of pollen
It is common to hear people say they are allergic to colorful or scented flowers like roses. In fact, only florists, gardeners, and others who have prolonged, close contact with flowers are likely to be sensitive to pollen from these plants. Most people have little contact with the large, heavy, waxy pollen grains of such flowering plants because this type of pollen is not carried by wind but by insects such as butterflies and bees.
Generally, it is tree, grass and weed pollens that cause the more common allergic reactions.
The tiny grains of pollen readily become airborne and are capable of travelling significant distances away from their source.
Although there are more than 1,000 species of grass, only a few produce highly allergenic pollen.
Pollens which you may be allergic to:
Besides self-help and allergen avoidance, it's important to get your hay fever medication right. What you use needs to be safe and effective.
If you are still using sedating anti-histamines, think about the impact the side effects may have on work or school performance and on activities like driving or operating machinery. There are non-sedating alternatives available. It may also be that your medication is not effective for the level of your hay fever symptoms. Again, there are many other options.
Most hay fever medications are available over-the-counter but if your usual tablet or spray is not controlling your symptoms, or if you are experiencing side effects, it's worth asking your pharmacist for advice.
Dr Wyatt blogs on his lifetime's experience of Indoor Air Quality Issues.