Allergic rhinitis is caused when the immune system encounters an allergen and treats it as if it is harmful, a consequence of which is the symptoms of allergic rhinitis.
It is not the case that an allergic reaction will occur immediately once an allergen is encountered. The immune system first has to encounter the allergen and essentially memorise it – a process known as sensitisation, after which if the immune system is oversensitive it will start to produce antibodies to fight against it. If a sensitivity is developed to an allergen, every time that allergen finds its way into the nose or throat antibodies called immunoglobulin E (IgE) are created which then form the basis of the symptoms of allergic rhinitis.
There are a number of different types of allergens that are commonly associated with allergic rhinitis; pollen (causing hay fever) dust, mould and fungi being very common types of allergens. A predisposition genetically towards the development of the condition and also environmental factors play a role.
Broadly speaking, the allergens can be broken down into four main categories –
- Allergens expressly encountered at work
- Tree, grass and weed allergens
- Allergens from animal hair
- House dust allergens
Workplace allergens
There are specific substances that have been found to cause allergic rhinitis in some people, so if your profession requires you to come into contact with one or more of the allergens on this list then you are at an increased risk of developing allergic rhinitis.
These at risk substances include –
- Antibiotics
- Azodicarbonamide
- Castor bean dust
- Cimetidine
- Crustaceans arising from food processing
- Dusts from agricultural work (harvesting, sowing, cultivating, milling, handling and transporting barley, maize, oats, rye and wheat)
- Flour (milling, storing and transporting)
- Fumes from rosin when used as a soldering flux
- Fumes from welding stainless steel
- Fumes of dusts from hardening agents based on phthalic anhydride, tetrachlorophthalic anhydride, trimellitic anhydride or triethylenetetramine
- Glutaraldehyde
- Green coffee bean dust
- Henna
- Isocyanates
- Insects and arthropods used for pest control, fruit cultivation or research in laboratories
- Ipecacuanha
- Ispaghula
- Natural rubber latex products
- Persulphate salts
- Platinum salts
- Proteolytic enzymes
- Reactive dyes
- Soya bean
- Tea dust
- Wood dust
Tree, grass and weed allergens
Depending on the time of year there will be different types of allergens present as trees, grasses and weeds will create pollen from Spring through to late Autumn.
Specifically the types of trees that produce allergens include –
- Alder
- Birch (highly common)
- Cedar
- Hazel
- Hinoki
- Hornbeam
- Horse Chestnut
- Linden
- Olive
- Pine
- Plane
- Poplar
- Sugi
- Willow
Grasses include –
- Ryegrass
- Timothy
Weeds include –
- Fat Hen
- Mugwort
- Nettle
- Plantain
- Ragweed
- Sorrel
In addition mould spores are typically present all year but peak around harvesting time in the autumn and in damp, mild weather conditions.
Animal hair allergens
It is important to note that the allergens are carried on the hair of the animal. It is not the actual hair or fur that causes the allergen, it is the dead animal skin flakes, saliva or urine that is carried on the hair. Studies have shown that exposure to animals that commonly carry allergens in early life lessens the prevalence of suffering from this type of allergic rhinitis in later years.
Animals that are known to carry allergens on their hair include –
- Cats (highly common)
- Cattle
- Dogs (highly common)
- Horses
- Rabbits
- Rodents
House dust allergens
House dust allergens are a consequence of house dust mites which tend to live in the house all year round but can peak when temperatures are in excess of 20 degrees C. Unpleasantly it is not the dust mites themselves that carry the allergen it is a chemical that is found in the excrement of the dust mite. They live on human skin flakes and are found commonly in the following locations around the home –
- Carpets
- Mattresses
- Pillows
- Sheets