Asthma has become one of the most common chronic disorders in the developed world. Asthma is difficult to describe, but the International Consensus Report on the Diagnosis and Management of Asthma defines it the following way: “Asthma is a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role".
Throughout the developed world, typically 5% of adults and 10% of children have clinically significant asthma. Its prevalence has increased significantly over the last 25 years and is now thought to affect around 300 million people worldwide.
Asthma can be a serious condition, which occasionally proves fatal, accounting for 1,131 deaths in the UK in 2009. However, most deaths and hospital admissions for asthma are preventable. Asthma is a condition that can be managed successfully and part of that management should include a strategy for allergen avoidance.
For example, in the UK, around 5.4 million people suffer from asthma, which includes 1.1 million children. The condition costs health services around £1 billion a year and accounts for an annual 1.1 million lost working days and around 80,000 hospital admissions.
Asthma comes in several forms
There are two primary types of asthma – childhood onset and adult onset. Most asthma does begin in childhood and is often associated with other related conditions like eczema and rhinitis.
Childhood onset asthma often has clearly identifiable triggers which will bring on an attack.
Adult onset asthma may be a continuation of childhood onset asthma, or it may be a new onset of the condition. Asthma can occur at any age, and should be considered in anyone who has a chronic cough. In adult onset asthma, there is often no obvious trigger, except for a chest infection.
There are also several sub-categories of asthma, including:
It can run in families
Asthma tends to run in families. However, asthma is not a single-gene disorder, with a clear line of inheritance. There are several ‘susceptibility’ genes involved in asthma, each contributing to the risk of developing the disease.
Diagnosis depends upon the doctor taking a careful medical history from the patient and noting whether the hallmark symptoms of wheeze, chest tightness, breathlessness, and cough are present. There are no laboratory or other tests which can definitely diagnose asthma and distinguish it from other lung conditions. However, if your doctor suspects asthma you may be subject to breathing tests to help confirm the diagnosis. Such tests include:
Spirometry: Spirometry is breathing into a machine which measures how much air you can exhale, which shows whether the airways are obstructed or not.
Peak expiratory flow rate test: A small hand-held device, called a peak flow meter, is used to measure how fast you can blow air out of your lungs in one breath. The peak flow meter can be a useful tool to use yourself at home to monitor your asthma.
Skin prick, or blood tests, are often carried out to find out which allergens might be triggering your asthma.
Thorough diagnosis by a doctor is a must, as asthma can easily be mistaken for other conditions, including:
Asthma tends to be a chronic disease (that is once you have asthma it will remain with you for the rest of your life). However, around a half of children do ‘grow out of’ asthma by the time they become teenagers, sometimes to re-emerge in adulthood. Like other chronic diseases, such as diabetes, asthma is not curable in the same way that, say, an infection can be cured. However, asthma can be controlled successfully so you can still live a full life.
Why all the focus on air filter efficiency?
Designers of traditional air purifiers have a tough job. There are lots of different air purifiers, so how to stand out from the crowd? Well, a little like high end music systems, ‘measures of performance’ are created which appear important to potential buyers but which are pretty meaningless in practice, and then competing products can be compared, and superiority claimed, based on that same measure.
One such misleading measure is ‘filter efficiency’ where you often see a focus on the percentage of particulates (pollens, mould spores, pet dander and house dust mite excretions) captured by the filter in the air purifier. For example “my filter captures 99.7% of all particles and yours only captures 99.2%”, or “my filter captures smaller particles than yours does” and so on.
And it isn't just the %, some manufacturers stoop to terms such as 'True HEPA' to muddy the waters, when in fact there is no such thing, a filter either meets the standard for HEPA filters or it doesn't!
Sadly, the fact is that such measures are pretty much meaningless in the real world. But, you say, surely it matters how much of the particulates in the air, which may well be allergens, irritants and other pollution, the device filters out?
My reply is that there are at least two major problems with using this measure of air purifier effectiveness, both of which make the number, be it 90%, 95% or 99.97% ( or even in fact 100%! ), pretty much meaningless!
The filter % measures the wrong thing
Measuring the percentage of particulates that are captured from the air passing through the filter measures only that, the percentage of particulates captured from the air passing through the filter. It doesn’t measure the percentage reduction of particulates in the air in the room, and the relationship between the two is tenuous at best!
The unfortunate truth is that the air in the room is constantly changing (typically it is replaced hourly with contaminated air from outside and elsewhere in the home), the air passing through the device is immediately remixed with unclean air in the room and some of the air in the room never goes through the device at all. Some air never goes through the device because of insufficient air flow, temperature stratification and the formation of eddies (where the air in parts of the room rotates in a circular motion without ever moving through the air purifier).
Furthermore, as pointed out by the US Environmental Protection Agency;
"for typical room sizes, most portable air cleaners currently on the market do not have high enough air flows to effectively remove large particles such as pollen, dust mite and cockroach allergens"
The reason being that the larger (and heavier) particles, such as pollen, simply sink to the floor or onto other surfaces, ready to be re-distributed into the air when they are next disturbed!
If you model how air cleaners work and include the constant infiltration of polluted air from elsewhere, they can take hours to reach a stable minimum of pollution and that minimum is related to many factors, but only marginally to the efficiency of the filter itself.
Think of it this way, imagine that an air filter, which captures 99.7% of particulates, effectively reduces the amount of particulates in the air of a room, after several hours, by say 50%. Changing the filter to one which captures only 90% will only have a marginal effect, perhaps limiting the reduction to, say, only 46%.
Be it either 50% or 46%, it doesn’t matter – neither are nearly enough!
What about gasses?
Well, a HEPA filter only ‘traps’ particles down to a particular size, below that size they are not captured at all. And all of the basic technologies, HEPA, electrostatic and ionic completely fail to capture or neutralise polluting gasses which can themselves be breathing irritants and cause asthma attacks.
Then along came Airora ...
The problems outlined above have earned traditional air purifiers a poor reputation, to the point where physicians will generally only say “well try one, it might help”.
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.