For many people, the advent of the warm season is nothing to cheer about. Clouds of tree and grass pollen make their eyes water as if they were dicing onions and their wastepaper baskets overflow with tissues. An estimated 10-20% of population do indeed find that spring can really hang you up the most, as they suffer from seasonal allergic rhinitis, better known as hay fever, a disorder that comes and goes with the seasons: the flowering seasons of trees and grasses, and the sporing seasons of fungi. Hay fever has become epidemic with modern times. Every year, medical practitioners of many countries report an increase in consultation numbers.
The symptoms of hay fever are those as for other allergies. The intensity, however, varies greatly between individuals. For some it is just a minor nuisance, while others find their daily activities disrupted. In severe cases, the patient develops asthma or an allergy and sensitivity towards other allergens.
All kinds of pollen find their way into your home.
Pollen from trees, grasses and weeds are the most common triggers of allergic reactions. Less common, but also important, are the spores of a large variety of fungi. All of these allergens can make their way into your home. They are so lightweight that they easily float with moving air, or are carried inside on peoples’ clothes and animals’ furs. Generally, spring and summer are the worst seasons for sufferers. Some weeds and grasses, however, mature late in autumn. Autumn is also the season when the farmers cut grass to make hay. Haymaking not only releases pollen and fungus spores, but is also a very dusty business.
Because pollen and spores float easily in the air, updrafts and wind play a vital role in distributing the particles. The first warm days in spring produce vertical air currents, called thermals, that carry the allergens high into the atmosphere. There they catch a ride in the prevailing winds and travel several hundred kilometers before they settle down – perhaps in your living room. If the pollen and spores miss the ride, they will settle nearby when the air cools in the evening. Cool and humid air for most of the day will discourage them to travel in the first place.
Pollen cells rupture during and after rain and in periods of lightning. The pollen grains literally explode and release allergen-containing granules. Air samples taken in Australia after a bout of rain contained up to 50 times more allergens than in equivalent samples taken on a dry day. But rain is welcomed by hay fever sufferers, nevertheless, as the allergens eventually wash away.
Air pollution will aggravate the irritation and swelling of airways. Studies show that pollution increases the sensitivity to allergens. Sufferers of rhinitis become more responsive to allergens when exposed to high doses of ozone, while a link has been established between an increased sensitivity to pollen and vehicle exhaust pollutants, in particular diesel fumes. As a result, the numbers of patients with hay fever are greater in cities than they are in rural areas.
The cause of the problem, however, may not originate outdoors. Besides house plants that may release hay fever-causing allergens, there are other nasties growing inside your home – moulds. With even the best cleaning practices, you may never be able to completely get rid of this furry growth, especially in climates with high humidities that favors all-year-round growth. You may respond to the microscopic spores of mould in a similar way as you would to pollen from a plant.
Avoiding the hay fever-causing allergen is obviously the best cure. If you know you get an allergy from particular plant pollen, try to keep it out of your house or your car. Pharmaceutical companies sell various over-the-counter and prescription medicines for the hay fever sufferer, of which antihistamine is the most common. As the name suggests, antihistamine suppresses the release of cell histamine so that swelling and irritation is reduced. Medication that reduces the symptoms of the common cold, such as decongestants, also bring relief to hay fever sufferers.
Typical allergies and sensitivities caused by indoor air pollution
A pet allergy is equally as common as hayfever. In most cases, it is not the cat’s or dog’s hair that triggers an allergic reaction, but the protein in skin flakes (dander), urine or saliva of any pet.
Also known as allergic alveolitis, is an allergic reaction that occurs after frequent inhalation of organic dust, such as during harvesting or handling of grain, keeping commercial flocks of poultry and birds, or growing mushrooms. Farmers’ lung is the common name for this illness. The indoor air at home may harbor these pollutants if the building is located close to a place with such activities, or the air is contaminated with spores of mould. Otherwise, this type of allergy is rare in the home environment.
More likely a health threat at home is humidifier fever. What is good for offices may as well be good for home – a controlled climate. In addition to central heating and air conditioning systems, many modern homes now boast humidifiers that control, as the name suggests, the indoor humidity levels. When these appliances are poorly maintained, excessive growth of algae, amoebae, bacteria and fungi may cause various types of humidifier fever.
The indoor air is a complex mixture of natural and man-made chemicals, to which we are exposed up to 90% of our lifetime. If a normal person inhales a certain amount of insecticide, for example, then the body reaction is quite predictable. The manufacturers and health authorities established thresholds at which certain health effects will occur. Highly sensitive people, however, may experience negative health effects at much lower doses.
Mold allergy, mould allergy
A close relative to hay fever is mold allergy. Mould allergy can occur all year when large numbers of fungal spores from indoor sources are released into the indoor air. Because the spores are microscopic in size, they can easily get past the first lines of defence in nose and throat and reach the lungs.
Dust mite allergy
It is an allergy to the protein contained in the microscopic waste-products of dust mites that live in the dust that is found everywhere in buildings. Dust mites are a very common cause of allergic rhinitis. The allergy also produces symptoms similar to hay fever and can also trigger asthma.
The thin and transparent membrane that lines the eyelids and covers part of the eyeball becomes inflamed. It is characterized by redness of the eye and a feeling of grittiness or itching. The eyes become watery and pus may develop. Allergic conjunctivitis often occurs simultaneously with other allergic reactions.