Understanding the role of pollen in allergy and asthma

What is pollen?

Pollen is a very fine powder that is produced and released by plants (trees, weeds, flowers, grasses) to fertilise other plants of the same species. Pollen is typically dispersed in the wind, but can also be transported from plant to plant by birds and insects.

What is a pollen allergy?

Pollen consists of tiny particles which, when inhaled, can trigger symptoms of allergic rhinitis (hay fever) and exacerbate asthma in susceptible individuals. Common symptoms of allergic rhinitis and asthma include (NIAID, 2015):

– Sneezing
– Increased mucous production (i.e. a runny nose)
– Nasal itchiness
– Post-nasal drip
– Itchy, red, watery eyes
– Nasal congestion (i.e. blocked nose)
– Coughing
– Wheezing
– Chest tightness
– Shortness of breath

Pollen is one of the most common triggers of seasonal allergies. A seasonal allergy is where individuals only experience allergic symptoms for the period or season, the pollen to which they are allergic, is in the air. Wind-borne pollens from trees, grasses and weeds, tend to be more highly allergenic and the cause of most allergy problems. However, not all pollen allergies are the same, nor are they restricted to only cause allergic symptoms during spring.

There are countless different types of pollen, and the timing and duration of pollen seasons differ depending on the plant varieties involved. In Australia grasses tend to pollinate during spring and summer, trees in late winter and early spring, and weeds from August through to May. Thus, depending on the pollen allergen or allergens involved, the severity of pollen allergies can vary considerably from one individual to another.

How are pollen allergies diagnosed?

The diagnosis of pollen allergies is complicated, and individuals should always seek the assistance of a qualified medical professional. A careful clinical history will need to be taken to pinpoint the timing of symptoms, identify the plants and trees common to the region of inhabitance, and determine whether symptom relief can be obtained by going on holiday. Allergy testing in the form of a skin prick test or allergen-specific IgE blood test, using pollen allergens relevant to the region, should then be performed and interpreted in conjunction with the individual’s history (ASCIA, 2015).

At the Australian Allergy Centre, skin prick testing for airborne allergens (such as pollens, dust mites, mould and animal dander) is performed under the cover of Medicare. All consultations with our doctors are Medicare rebatable and no referral is necessary.

Pollen counts and forecasts

Pollen counts and forecasts are important to help pollen allergy sufferers plan their day. Pollen counts tell us how many grains of pollen are in a certain amount of air during a certain amount of time. Many pollen forecasts will also provide a rating (low, medium, high or extreme) of pollen allergenicity (the potential for pollen to trigger allergic reactions in susceptible people) alongside the numerical count, which takes into consideration both the type and concentration of pollen in the air.

There are many different factors that influence pollen concentration in the air, including type of pollens, time of day, weather and geographical location. In Australia pollen counts are usually highest between 6am and midday. They are usually higher on warm, breezy days, and lower on cool, wet days. Though rain can help to reduce pollen counts by washing the pollen away, rain is somewhat of a double-edged sword. When pollen granules come into contact with water they burst and release hundreds of smaller allergenic particles (ASCIA, 2015; NIAID, 2015).

Pollen counts tend to be higher in inland areas where there are no natural barriers to wind dispersal, and lower by the seaside where prevailing winds come from the sea. This is particularly true on the East coast of Australia (ASCIA, 2015).

How are pollen allergies managed?

Upon diagnosis, there are three main methods for managing pollen allergies: allergen avoidance, pharmacotherapy, and allergen-specific immunotherapy.

ALLERGEN AVOIDANCE

Allergen avoidance measures often necessitate a change in behaviour patterns. Unfortunately the complete avoidance of pollen can be difficult as pollen can travel long distances with the wind.

Some tips to reduce exposure to pollen include (ASCIA, 2015):
– Stay indoors until after midday. (Pollen in the air is usually highest between 6:00am and noon)
– Avoid activities known to cause exposure to pollen, such as mowing grass. If unavoidable wear a mask or consider taking a non-drowsy antihistamine prior.
– Avoid planning outdoor activities in parks and the countryside during pollen season. (Pollen counts are usually higher in inland areas and lower on the coast)
– Avoid going outside on windy days or after rain. (When pollen granules come into contact with water they can burst and release hundreds of smaller allergenic particles)
– Wear sunglasses when outside to protect eyes from pollen
– Shower after outdoor activities, and rinse eyes with water
– Keep windows closed at home and in your car, and use recirculated air-conditioning in the car when pollen counts are high
– Tumble dry bedding and clothing during pollen season
– Consider planting a low-allergenic garden around your home
– Wash your pet weekly

PHARMACOTHERAPY

The elimination and avoidance of pollen allergens is not always possible, or achievable to the extent individuals are effectively relieved of their allergic symptoms. There are however many pharmaceutical treatments available, both over-the-counter and by doctor’s prescription, which can help allergy sufferers gain symptom relief. Commonly used treatments include decongestant, antihistamine and steroid nasal sprays, oral antihistamines, and bronchodilator aerosol inhalers. Natural products such as saline nasal sprays and irrigations can also be effective in helping to relieve symptoms, by flushing allergens from the nasal passages and sinuses (ASCIA, 2015).

It is important to note these treatments are designed to provide alleviation from symptoms only; they do not treat the cause. Seeking advice from a qualified medical professional or pharmacist prior to commencing treatments, is always recommended.

ALLERGEN-SPECIFIC IMMUNOTHERAPY

Allergen-specific immunotherapy or “desensitisation” is the only treatment available which targets the cause of allergy (e.g. pollen) rather than just the symptoms. Immunotherapy “switches off” the allergy, by changing the way the immune system reacts to offending allergens. Pollen allergen immunotherapy is often recommended for individuals suffering from severe allergic symptoms, to which allergen avoidance techniques are insufficient and pharmaceutical therapies are ineffective and/or inappropriate (ASCIA, 2015).

Reference:

Australasian Society of Clinical Immunology and Allergy [ASCIA]. 2015. Pollen allergy: Information for patients, consumers and carers. Accessed September 29, 2015, http://www.allergy.org.au/images/pcc/ASCIA_PCC_Pollen_allergy_2015.pdf

National Institute of Allergy and Infectious Diseases [NIAID]. 2015. Pollen Allergy. Accessed September 29, 2015,http://www.niaid.nih.gov/topics/allergicdiseases/documents/pollenallergyfactsheet.pdf