Author: Dr Tim Aung, Primary Care Practitioner, Brisbane & Logan, Queensland, Australia. DermNet Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. February 2019.
Aeroallergens are various airborne substances or inhalants, such as pollens, spores, and other biological or non-biological airborne particles that can cause allergic disorders. Inhalation or cutaneous contact with aeroallergens can trigger a release of proteins in the form of an allergic reaction on the skin and mucous membranes [1,2].
Airborne particles can also cause irritant reactions without causing an immunological response.
Which are the most common aeroallergens?
The most common aeroallergens causing disease are pollens and house dust mites. Pollens are derived from:
Tobacco smoke (a common irritant and a rare allergen).
Combustion product irritants include:
Carbon dioxide (CO2)
Carbon monoxide (CO)
Nitrogen dioxide (NO2)
Sulphur dioxide (SO2)
Volatile organic compounds
Lead (Pb)
Other particulate matter
Ozone.
Who gets diseases from aeroallergens?
Allergies only affect susceptible individuals (see DermNet's page Allergies explained) whereas irritant reactions can affect anyone.
The prevalence of aeroallergens is quite variable from one region or country to another, depending on the climate, the local plants and animals, and the degree of pollution [3,4].
Climate change has been reported to contribute to the rise of some types of aeroallergens and to a surge in allergic disorders [5–7].
Pollen aeroallergens are prevalent in temperate zone countries.
Pollen counts vary with exact location and flora, time of year, altitude, temperature, humidity, wind, electrical activity, and rain [8].
In New Zealand, the main aeroallergens are grasses [8]. The pollen season lasts for about 34 weeks beginning in July or August.
In Scandinavia, the main allergen is birch.
In North America, the main aeroallergens are ragweed and deciduous tree pollens.
Olive pollen is prevalent in the Mediterranean.
Feverfew and mugwort are important aeroallergens in Eastern Europe and India.
In Japan, the Japanese cedar is responsible for many cases of pollen allergy.
Pollen forecast 18 February 2019, Hamilton, New Zealand
How do aeroallergens cause disease?
Although usually due to other factors, some common skin conditions are occasionally triggered or aggravated by aeroallergens [9–11]. How this occurs remains unclear (see figures 1 and 2 below for proposed mechanisms).
Figure 1. Induction and effector mechanisms in type I hypersensitivity
Induction and effector mechanisms in Type 1 hypersensitivity
Aeroallergens commonly cause allergic rhinitis, allergic conjunctivitis, and allergic asthma, and they may contribute to eosinophilicoesophagitis [14–16].
Skin conditions due to aeroallergens are less common. These include:
The avoidance and elimination of aeroallergen triggers can be challenging.
Pollens
Be aware of the allergenic plants in your region and monitor the local pollen forecast. Stay indoors and consider taking antihistamines and other medications when the pollen count is high.
Moulds
Thoroughly clean contaminated areas such as bathrooms, laundries, and basements. Ventilate damp areas to prevent the growth of moulds.
House dust mites
Clean and vacuum all pillows, mattresses, bed-sheets, towels, carpets, and upholstered furniture. Consider using pillow and mattress protectors to minimise house dust mites.
Animal dander and fur
Avoid contact with animals if possible. Bathe pets regularly.
What is the treatment for aeroallergen allergy?
The treatment of an aeroallergen allergic disease depends on the symptoms experienced.
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