Gentowa

The skin tests are necessary supplements of all basic allergist examinations. The allergichypersensitiveness proof was discovered by Charlie Blackley already in 1865. The techniquewas later on improved by Grant Lewis, Pepyes and others, who introduced the prick test (stinger) usage. Nowadays the standardized method introduced by the European allergist andclinical immunology academy. The skin test in based on the fact, that sensitive allergic patient has specific antibodiesagainst the allergens not only in the particular organ, in which the clinical symptoms areactive, but also in the cell membrane – mastocyte which are in the skin.

While testing, the suspect allergen is injected into the patients´ skin near the forearm.

 The allergen choice is made according to the patients´ data on the clinical symptoms period.

The standard group of allergens, which includes the following, is used:

 ● trees pollen

● grass pollen

● rye

● worm wood

● ambrosia

● mould

● feather

● mites

● positive control (histamine)

●negative control (usually a solution with dissolved allergens)

According to the seasonality, others allergens are added. If the patient is in the contactwith the animals, the animal allergens (dog, cat, etc) are tested, as well. Before the testing thepatient should cease the anti allergic treatment (the antihistamines for at least one week), butothers, as well. For example many preparations used by the psychiatrists relieve even the skin reaction at the skin tests.

When possible, the patient should be tested even off pollen season. It is notappropriate to test somebody during or right after the infection since it can cover the reaction,as well.

For checking the skin test realisation correctness beside the allergens, the positive andthe negative control is injected. As the positive control histamine is used – a chemical, whichis released during the allergic reaction in general, i.e. test with this chemical can be positiveeven in the case of the health people. If this reaction after the testing is negative, the test is notvalid, since some of the processes or the medications relieved all reactions.The negative checking is, on the contrary, is injected in order to exclude the reaction,which is only mechanical – the injury or the injection itself, or the allergic reaction to thesolution, eventually to the conservative chemical in the allergen solution.

The skin tests allergens are made commercially. Their content and dilution are standardised.

It´s description is the most important part of the “testimony” andno basic information can be omitted in it.

● illness start and description

● your own symptoms descriptions

● seasonal presence of the clinical effects (per year, during the summer, etc)

● allergic (not allergic) initiating factor – if we know it or if it seems to be assumed

● lifestyle influence * the symptoms occurrence frequency and the seriousness symptoms * influence on the occupation ( study) * extra working activities (sport, hobby) * sleep

● environmental allergens – surroundings allergens – (at home, work)

● existing treatment – ( if already treated)* effect (little, significant; stopped to be effective after a period of time)* side-effects* satisfaction and the willingness to undergo this type of treatment.The information on the further potential illnesses we have, especially onmedications we take, is important. Many can influence not only the diagnosis, but also theparticular allergic reaction itself – and not only in the negative sense – worsen of the clinical condition or on the contrary- covering of the particular typical symptoms.

The physical examination is the basis in all cases. The doctor examines all systems.He or she examines the skin al over the body, where the symptoms – even not the mostserious and hence hidden, which the patient himself does not have to notice – inflammation,reaction to any mechanic irritation, dryness or wetness of the skin, nails, hair, are looked for.

The oral cavity reveals the potential inflammation- infectious, but allergic, as well.The nasal mucosa swelling and congestion, nasal discharge, red skin around the nostrilscaused by the mechanic irritation are the symptoms of the common cold. The patients with thenasal congestion breathe through the mouth, which are open all the time. The nasal congestionAs far as the children are concerned, the nasal congestion is revealed by the line on the top,especially the so called allergic salute (greeting), it is started with. It is a “gesture” of pushingthe top of the nose up with the palm, while the nasal cavity is being released.

The auscultatory examination – examination with the phonendoscope – enables to hearthe breathing sound. Unlike the healthy lungs, the patients with the clinical asthma makecrunching, bubbling or whistling sounds while breathing. They do not have to be loud so thatonly the experienced ear of the doctor can hear and identify them.The palpating and percussing of the rib cage and the abdomen provides furtherinformation.The entire examination, especially the first visit to the specialised doctor is necessary.Therefore even while examining the patients, who are think that they have “only” a commoncold, we should expect the complex examination.

The allergic reaction, which appears in the eyes, is relatively common. It usually occurs together with the allergic common cold; through it rarely appears in the exe area only. Not for all the symptoms, which are regarded as the “red eyes”, the term allergy is correct. In addition to the reaction to the external irritation – the contact with the essential matter or dust, the infections and autoimmune disease can be taken into consideration, as well. The most common eye allergic disease is the allergic conjunctivitis – i.e. the pinkeye, which cover 25% of the population.

The conjunctiva is a thin phlegmy membrane, which covers the eye (the front side), the eyelash from the inner side hence it forms the so called eye conjunctiva bag. Since it is “stuffed” by the lymphocytes, eosinofilms and mastocytes it is a tissue, which the allergic reaction can appear in.

What are the allergic pink eye symptoms?

Usually the symptoms appear in different intensity, yet not all the symptoms appear at the same time. The common allergic conjunctivitis symptoms include the following:

● eye itch

● red eyes (red blood vessels)

● sore eyes

● lachrymation, often very intensive

● light sensitivity

The most typical symptom is the eye itch. The photophobia relates to the tingling feelings in the eyes during the increased light intensity. As for the unpleasant pinkeye side effects, the patients describe the sore eyes as having their eyes sprinkled with the sand. However, the eye does not hurt and if it does it is not the allergy. The allergic conjunctivitis can be distinguished according to the duration and season, in which it appears, into seasonal and perennial.

The seasonal is initiated by the pollen allergens and in most cases it accompanies the allergic common cold. Often the eyes symptoms appear at first, followed by the developing common cold. The symptoms can be observed on both eyes. However, their seriousness can differ – one eye can itch more than the other, and so on. While having only one inflamed eye, the disease can not be regarded as the allergic conjunctivitis.

The perennial allergic conjunctivitis is caused by the year – long appearing allergen contact – the mites, animal epithelium, moulds, which often occur together with the atopic eczema or even the asthma and sometimes is combined with the common cold. In most cases the inflammation gets worse during the pollen season. The conjunctivitis can be combined with the cornea inflammation - in this case we talk about the keratoconjunctivitis, which is more serious.

The vernal conjunctivitis has its name delivered from the fact that it appears in the spring time. Its development is regarded more serious. In addition to the common symptoms –itching, burning and shedding tears, the eye reacts with the megascopic protuberance – the capillaries. This inflammation can have complications, which can lead to the lost ob the patient’s sight. It can spread on the eye cornea and hence reduce the eye defensiveness to such a degree that the infection can start, as well.

The vernal conjunctivitis affects usually the children and the young population. The adults are affected by it only rare. The conjunctivitis is directly caused by the contact lens material, probably “in cooperation with “the mechanic eye irritation, hence as the contact lens started to be worn, the conjunctivitis has been spread. The gigantic papillary conjunctivitis – as this disease is called – is developing gradually and is a result of the intolerance of the lens, which can not be bear anymore. If we suspect any kind of illness disease in the eye, the ophthalmologic examination will be necessary. Do not try to treat these symptoms alone without an eye specialist.The allergic conjunctivitis therapy is connected with the allergic side effect therapy. It is based on the antihistamines – local and general.

Our market offers following preparations: levokabasine – LIVOSTIN, aselastine – ALLERGODIL, lodoxamide – ALOMIDE. For a long lasting therapy, even local cromoglycates – CROMMOHEXAL are used. In the case of massive inflammation, the short or long lasting corticoids can be used after the ophthalmologist´ s decision.

How the allergy is diagnosed by the doctor

The diagnosis procedure is not easy. The clinical symptoms of the different originillness are often similar. For instance the symptoms of the allergic fever – red stuffy nose,sneezing, nose secretion are the same as while having the cold (it is usually caused by asimple viral inflammation). But the treatment approach is different.

Therefore the diagnosisprocedure requires besides the judgement of the current health conditions further information, too. The basis of all allergic examination is the detailed anamnesis. It is actually the list of all factors, which relate (sometimes only seemingly for the patients) to the illnesses.

The family anamnesis is an information on the illnesses appeared in the patientfamily. Naturally, the blood relations, not he wife or the brother-in-law, are important. Theallergic reaction, their ancestors – father, grandmother, siblings or children-suffered from,indicates the relation to the current illness of the patient. The allergy predisposition isinherited. While the child of the parents, who do not suffer any allergy, inclines to the allergyat the odds of approximately 20%, the odds of the allergy increases up to 50% concerning thechild of at least one allergic parent. If the mother suffers any allergy, the odds will increaseeven more and in the case of both allergic parents, it is almost 100% certain, that their child will suffer the allergy (especially if both parents are allergic to the same allergens).

Personal anamnesis

includes the facts, which precedes the particular current illness.In the anamnesis, all the previous illnesses, we have undergone, are listened. The eczemas inthe childhood, serious allergic reaction suffered years ago, or the repeated infections – allthese are information, which indicate the possible immune system disorder or direct theallergic “before-period”.Concerning the women the important information is the number of the deliveries andthe development of the pregnancy, concerning the children, the time until they were nursed, when they started to eat the baby food, is of the greatest importance.

The working anamnesis

is the information on the surroundings, where we spend themain part of our day. The important facts refer not only to conditions of the building(cleanness, humidity, thermo regime) but also all things we come into contact with – theproduction, administration, special operations and chemicals. The significant information arethe protection regime against the potential harmful chemicals at the workplace and ourapproach to it. The information about how we spend our spare time – our hobbies, the sport, etc, places where we have the chance of the contact with the factors initiating or starting the allergy, should be a part of this analysis, too.

During the last hundred years the people have changed their eating habits, especiallythe content and preparation of the foodstuffs to such a degree than the whole existence hasnever achieved before. Today we can not find any foodstuffs, which would not b prepared insome way. The chemical conservation, colouring and flavouring of the foodstuffs and drinks is common procedure of their preparation.

The food industry nowadays uses for this sake tens of chemical compounds. It isobvious that the doses contained in the foodstuffs can not be toxic for the human body. Thisprinciple is controlled strictly by the particular authorities of the hygienic services. Thecolouring flavours can not be added to the fresh vegetable, fruit, coffee, tea. The butter, breadand milk might not be coloured with the synthetic colouring flavours. The conservative chemicals should not be added to milk, flour, bread, baby foods.

From time to time an affair comes up, related to the mass intoxication (let us mentionthe Spanish oils), but in this case it is always the human factor which failed. The reliable foodproducers can not afford in no case to go beyond the norms, which are stated for the particularadditives – as these chemicals are called. While developing these chemicals, the allergicpeople had been forgotten. Therefore we are now in the situation, when the huge amount ofthe allergic reactions is caused not by the foodstuffs itself, but by the chemicals added to it – whether as a result of their taste, smell, colour, or because of the freshness.

Tartrazine (E 102) is an orange colouring additive used perhaps to the greatest extent. Itis added to the whole range of foodstuffs and drugs, too. That might be the reason why it isthe well known and often food allergen (0, 5% of the population reacts to it). It becomes thesuspicious factor for the patients, who are allergic to foodstuffs without any relations among themselves (for example, the canned meat, ice-cream, sauce, conserves, chew gum, juice).

Sulphides (E 223) are used because of their antibacterial and antioxidant effects. They arecontained in the dried meals (fishes, fruits) and added to drinks (beer, wine, fruit andvegetable juices). In addition to the allergic reactions related to the food allergic sufferers, they worsen the health condition of up to 10% of the people suffering the asthma.

Parabenes (E 127) are often used in the food industry, but also in the drugs and cosmeticsproduction because of their antibacterial and antifungal effects. Pay attention to the dentalwaters and teeth pastes. They cause the allergic reaction, which affect the skin the most (eczema, urticaria).

Erythrosine (E 127) is a red water-soluble colouring additive used in the food industryand the drugs production. We van find it almost in all commercially produced foodstuffs, which are red. It causes all possible clinical forms of allergic reactions.

Carotenoids (E 160) are red colouring additives used in many foodstuffs (pasta, bakeryproducts, candies, ice-creams, fried milk creams, dry pastry, candies, mayonnaise products,mayonnaises, drinks, vinegar, powdered drinks, fruit and vegetable products, oils and fats,soups, pre-cooked rice, milk products, food concentrates, mustard, fish and poultry products,soup preparation products, powdered meals preparation mixtures, sauces). They cause the allergic reaction especially when the patients are allergic to some kind of vegetable.

Benzoates (E 210-219) belong to the most commonly used conservative chemicals. The allergic reactions caused by them have different clinical development.

Monosodium glutamate (E 621) is added as a flavour to the soups, sauces, and meatpreparation products. It can cause so called Chinese restaurant syndrome. It is not good for the little babies.

Butylhydroxyanisole (E 320) added to the majority of the foodstuffs as an antioxidant –to oils, fats, emulsified fats, candy products, soup and sauce preparation products, ketchups,flavoured vegetable creams, mayonnaise, flavoured horseradish, garlic paste, mustard, nutkernels, chew gums, products on the basis of the boiled potatoes, fried semi finished potato products.

Summary of the additive coding

E100 - E199 Foodstuffs colouring additives

E200 – E299 Conservative agents

E300 – E321 Antioxidants

E322 – E495 Emulsifiers, stabilizers, jelly reagents

E 500 – 3619 Acids, alkalis ( E 260, 270, 330, 334, as well)

E620 – E637 Taste flavours

E900 – E925 Various

E1000 - Others

RememberAccording to the food law the producers must obligatory label and mark the foodstuffs.The consumers must be informed on the content and composition of the packedfoodstuffs. The list of the particular components should be listened in the downwardorder – according to the declining amount.

The additive can me marked by the name orthe number code. In the European countries the initial E letter, established already 30years ago within the European system, is used. The INS (International NumberingSystem) labelling, which is identical with the E system, has started to be used. It enablesthe orientation in the food industry additives within the whole world.

Red and white beans

are often food components used in sauces or soups. They are oftenadded to canned meat food products. The patients often cross-react to other kinds of legumes,as well.

Soya beans are the most frequently used legume worldwide. Soya is used in various forms– starting with the traditional legumes, continuing with prepared foodstuff – tofu, soya fibre,soya “meat”. The soya sauce is a part of mixed sauces and dressings. According to itsfrequent usage it belongs to the most common causes of the allergic reactions. Moreover, thedisoriented patients, especially the parents of children suffering some allergies think that soyamilk can substitute the cows´ milk. The reverse is true! Offering another allergen, althoughany cross-reaction is threatening, is unsuitable for children.

The cross-reaction occurs withpeas, peanuts and other legumes.Meals which can contain the soya protein:

● ready made baby food

● bakery products

● pudding

● bread

● hamburger

● butter adjunct

● chocolate

● meat products

● sausages

● soups

● crackers

● dressings

● deserts

● ice-cream

● canned meat

● caned fish

Peas and lentils

do not belong to often allergens in these latitudes (in India it is the fifthmost common allergen). Those allergic to these legumes should be careful. Peas are added tovarious meals, for example mayonnaise and sandwiches.

Peanuts (groundnuts)

belong to the most common food allergens at all. In the UnitedStates it is the number one in particular because of the fact, that the peanut butter iscommonly used in American cuisine. This vice has already appeared in Europe – just think ofall the Nutela peanut butters and other sweet spreads, waffle fillings, etc.The peanut as an allergen is dangerous since its oil is added to the whole range offoodstuffs, while, unfortunately, this information is not written on the cover of the foodstuff!This goes for various sauces, cakes, ice-creams and flavours. It is often used for thickeningthe meals – mostly various barbecue sauces. Traces of peanuts allergens are marked even infoodstuffs, which do not contain any peanuts at all – as a result of the previous productionprocess of the production devices. After eating such foodstuff, a serious allergic reaction wasprecipitated. In the United States several tens of people die as a result of the anaphylacticshock after eating the peanuts or their parts.The cross-reaction can occur with other legumes.

Nuts and seeds

Many seeds inside the shells are regarded as nuts, although from the botanic point ofview they do not belong to this group of fruit. As foodstuff they are used commonlywhether as food supplements because of their high level of proteins and oils, or becauseof their taste.

The seeds and nuts are often allergens and danger the allergic people perhaps the mostbecause they are contained in many food products. The various bakery products – breads,pastry, cakes, cereals, candies, sweets, ice-creams, drinks, chocolate products, desserts, milkproducts and hundreds other products contain some of the nuts or seeds. The great danger forthe allergic people lies in the fact that many products contain such a small amount of theseelements so that the producer does not declare it. The patients allergic to some of thefollowing seeds or nuts have to be very careful while choosing their foodstuffs.

Almonds

are stone fruit kernels of typical taste. According to the presence or absence of theglycoside, which is called amygdaline, they are divided into bitter and sweet types. Thekernels are eaten either alone – roasted and salted or added to various products – ice-creams,chocolates, cakes, puddings, chew gums. Be careful – the almond oil is often added tocosmetic products.

Brazil nuts

are actually seeds from huge trees, growing in the wildness of the SouthAmerica and in the rain forests of the Amazon region. The trees are not planted, but the cropand the export of the seeds forms an important part of their economy. Inside the big fruit-up totwo kilograms of weigh- with the wooden shell, 10-22 seeds are growing. The nuts with ahigh nutritional value and 60 or more percentage content of the oil and 17% of the proteins.

Food of vegetable origin Cereals

Common cereal seeds are well known allergens. In addition to the sugar, they consistof proteins, which are most responsible for the allergic reaction. Barley, wheat, rye, corn, rice,oat and millet are counted here. The reaction by which the human body is allergic to proteinsof barley, wheat and rye – gluten and gliadin should be distinguished from the classicalallergic reactions. This disease is caused by innate metabolism anomaly.

Barley

is often planted cereal for it is not only a component of the food chain, but also acereal the liquors are made of. The patients allergic to barley products and often to liquorscross-react to ray and wheat. Be careful with the beer.

Malt, mostly made of barley, is a number of germinated, dried, and ground cereal grains. Atthis process it comes to changes. Many sugars and proteins of the original cereals aredenaturalised. In addition to the production of beer and whisky, the malt is being used also asan adjunct to cereals (flakes) and filling of different cakes.

Buckwheat

does not belong to the true cereals. In Europe it belongs to often used foodstuff.It is used in the pancake filling and other pasta (spaghetti, macaroni) and is part of many babyfood products. In Japan the buckwheat belongs to major allergens – it is often used in thenoodles.

Corn

comes from America, from which it spread to the whole world. It is used in a range offoodstuff products from corn flour, but also boiled – independently, or in salads. It is often acomponent of the baby food products. The corn flour fills many foodstuff products. Whiskeyof the bourbon type (USA) is made of corn flour.

Millet

is used in Europe not so often. It is used especially in Asia. For example in India it isconsumed more frequent than the wheat in European countries. Since it cross-reacts only rarewith other cereals, this type of cereal can be used as a substitution to patients who are allergicto wheat or rice.

Oat

belongs in the last decades to frequently used foodstuff – especially as an advantageousfibrous food adjunct for example in the form of flakes typically prepared for the breakfast.It is used in soups, sauces, yogurts and different types of foodstuff.

Rice

is a basic food component of more than half of the human population. It comprises 20%of all calories consumed per day in the world. The rice flour is used as a starchy filling in therange of food products. Fortunately it does not belong to often food allergens.

Wheat

probably belongs to the most used food components in the world. Starting withtraditional bread, bakery products, cakes made from leavened dough (Europe, NorthAmerica), unleavened baked goods and pancakes (South America, Asia), pasta like couscous(Africa, Near East), macaroni, noodles, pasta (Mediterranean) – we can find wheat products inthe whole world. Wheat is very often – as so called “hidden allergen” used in other foodproducts. It is added to sausages, various smoked meat products, chips, fast food products,sauces – (commercially sold for example soya sauce) and candies. Since the sensitiveness atwheat is not rare in the case of both, adults and children, it is necessary to avoid food productscalled fast food, where even the seller need not to be aware of the information on thepresence of the wheat flour!The patients allergic to wheat can replace the wheat with rice or corn flour products.

Legumes

To these wide spread food products the following can be counted: read beans, white beans,soya beans, lentils, peas, peanuts, gum Arabic, fennel, liquorice (black sweet) . In addition topeanuts, which can be regarded as the most important food allergen, the legumes do notbelong to often causes of allergic reactions.

The pollen catcher is placed on the roof of the building. (The building should besituated representative enough for its surroundings, from which the information is given, thusnot near a factory or a chimney).The pollen catcher (pollen toils) - is a barrel with a vacuum cleaner, which draws in the airfrom the room and directs its flow with the help of the jet onto the adhesive tape.

All caught elements, which the air consists of, get caught on the adhesive tape. The tape isfixed on the inside of the barrel, which turns around slowly (360 degrees in seven days).The tape is removed from the barrel after a week, and is finally cut into seven piecesthat stand for particular days of the week. The pollen, which is caught on the rape, is colouredand finally evaluated under the microscope. Of course, these evaluations can be done only bythe experts, who can recognise and define the particular type of pollen drain according to itscolour, form and size.In addition to the type of pollen, the measurement of the pollen in the air has beenevaluated, as well.

The results are converted into 1 cubic metre. It is important, since thepatients react clinically to certain amount of the pollen in the air. The plants and flowers differin the aggressiveness from each other. To start the symptoms of the allergic reaction, 50pollen grains in 1 cubic metre are usually sufficient. While in season, the pollen count isseveral times higher.The pollen station sends the information to the centre (Štrbské Pleso in SR), whichprocesses the information and sends them to the central office in Vienna. At the same time,once in a week, it distributes the information to several doctors and public mass media.

The pollen calendar

The central office in Vienna under Dr. Siegfried Jäger processes the data fromEuropean pollen stations on the basis of the information gained. It enables to publish thepollen calendar periodically. It is a document - a map, which covers the pollen in the air indifferent European countries according to the months of the year.The calendar is important for all sufferers. The up–to-date month by month situationof the area where we are living at can be found here.We can find here the pollen situation in other countries, as well, which plays a significant rolefor everyone who is planning to travel abroad.The summary of the pollens in our country is shown in the following picture. Thevacation guideline for the allergic people can be found in the chapter Allergy on the road.

● Instead of feather pillows and duvets, it is required to use those plastic ones withplastic covers, as well, which do not cause allergic reaction

● Frequent changing and washing of clothes is necessary. Animal allergens often settlein there and can cause irritations even outside the place, where the animal is

.● It is necessary to wipe the floor and the furniture with a damp cloth. For vacuumcleaning only the vacuum cleaner with HEPA (high efficiency particulate arresting)filter is suitable.

The one being allergic should not come into the contact with vacuumcleaning. If he/she has to clean with the vacuum cleaner, he should use the maskprotecting himself from the dust. The air disposal plant is appropriate; it is able tofilter almost all flying dust, though it does not remove all allergens.We have to be aware of the important fact that: although all these activities reduce theamountof allergens in the family surroundings, they can not be substituted for the removal of theanimal. Even the removal itself without a special cleaning of the house means that you willlive in the environment surrounded by clinical important amount of allergens.All mentioned allergens can be, of course, found in dust. The dust by itself is formed by smallgrains of inorganic material - silica, together with other inorganic and organic matters andmentioned organic matters.

The home dust of particular households or working places varies according to the way a houseor working place is furnished.Therefore the diagnosis is made with individual allergens. The term “allergic to dust” does notindicate our actual reactions, therefore has been ceased to be used.The life of allergic people is getting worse even by other harmful substances, which donot start the actual allergic process, but get worse its development.

Pollen information service

The most frequent factor, which causes and starts the allergic reaction, is pollen. Thepollen count in the air directly influences the clinical symptoms, whereas there is a directrelationship between the amounts of pollen in the air and the seriousness of the symptoms. The seasons, when the flowers are in bloom and hence the pollen count is higher, can bepredicted approximately according to the usual duration of blooming time of the particularflower, which is stated in all botanic guidelines.However, the pollen calendars do not always correspond to the real time a flower is in bloom.The real bloom period can differ from the assumption even in several weeks. Moreover thelevel of the air pollen is noticeably influenced by meteorological conditions (rain, wind, coldheat,etc).

The up-to-date information about the situation i.e. what is the amount of pollen grainsand what kind of pollen grains are in the air, are necessary for the doctor and the patient, aswell.Within the information as a part of diagnosis the important anamnestic information –worsening or bettering of the patient’s health within a particular period, follows.Even more important is this information for the planning and conduction of the medicaltreatment.

While the air contains “our” particular allergen in the sufficient amount, the clinicalsymptoms arise.This can be prevented by taking the medicine on time. Its advantage lies in the fact, that in“our” season we can adjust our daily schedule (less walks, travelling to clinically betterenvironment and so on).The pollen count started to be examined already in 1873 by the English doctorBlackeley.

He suffered the allergy himself, and hence was interested in the possibleconnection between the amount of pollen in the air and the clinical seriousness of the allergy.He placed in different levels small glasses covered by glue, which caught the pollen.The need of exact information let to the gradual establishment of pollen stations,which measure the amount of pollen and other substances in the air. In 1930s first stationswere founded in Canada and USA.