Pollen and allergens
1. Buters J, Prank M, Sofiev M, Pusch G, Albertini R, Annesi-Maesano I, et al. Variation of the group 5 grass pollen allergen content of airborne pollen in relation to geographical location and time in season. J Allergy Clin Immunol 2015;136(1):87-95.
2. Galan C, Antunes C, Brandao R, Torres C, Garcia-Mozo H, Caeiro E, et al. Airborne olive pollen counts are not representative of exposure to the major olive allergen Ole e 1. Allergy 2013;68(6):809-812.
3. Buters JTM, Thibaudon M, Smith M, Kennedy R, Rantio-Lehtimaaki A, Albertini R, et al. Release of Bet v 1 from birch pollen from 5 European countries. Results from the HIALINE study. Atmos Environ 2012;55:496-505.
4. Durham SR, Nelson HS, Nolte H, Bernstein DI, Creticos PS, Li Z, et al. Magnitude of efficacy measurements in grass allergy immunotherapy trials is highly dependent on pollen exposure. Allergy 2014;69(5):617-623.
5. Sofiev M, Bergmann K. Allergenic pollen. A Review of the production, release, distribution and health impacts. Heidelberg: Springer Verlag; 2013.
6. Cecchi L. From pollen count to pollen potency: the molecular era of aerobiology. Eur Respir J 2013;42(4):898-900.
7. D'Amato G, Holgate ST, Pawankar R, Ledford DK, Cecchi L, Al-Ahmad M, et al. Meteorological conditions, climate change, new emerging factors, and asthma and related allergic disorders. A statement of the World Allergy Organization. World Allergy Organ J 2015;8(1):25.
8. Raulf M, Buters J, Chapman M, Cecchi L, de Blay F, Doekes G, et al. Monitoring of occupational and environmental aeroallergens-- EAACI Position Paper. Concerted action of the EAACI IG Occupational Allergy and Aerobiology & Air Pollution. Allergy 2014;69(10):1280-1299.
9. Caillaud DM, Martin S, Segala C, Besancenot JP, Clot B, Thibaudon M. Nonlinear short-term effects of airborne Poaceae levels on hay fever symptoms. J Allergy Clin Immunol 2012;130(3):812-814.
10. Thibaudon M, Sikoparija B, Oliver G, Smith M, Skjoth C. Ragweed pollen source inventory for France- the second largest centre of Ambrosia in Europe. Atmos Environ 2014;83:62-71.
11. Thibaudon M, Galán C, Lanzoni C, Monnier S. Validation of a new adhesive coating solution: comparative study of carbon tetrachloride and diethyl ether. Aerobiologia 2015; 31(1): 57-62.
12. Caillaud D, Martin S, Segala C, Besancenot JP, Clot B, Thibaudon M. Non linear short-term effects of airborne Poaceae levels on hay fever symptoms. J Allergy Clin Immunol 2012; 159(3): 812-4.
13. Eduard W. Fungal spores: a critical review of the toxicological and epidemiological evidence as a basis for occupational exposure limit setting. Crit Rev Toxicol 2009;39(10):799-864.
14. Ege MJ, Mayer M, Normand AC, Genuneit J, Cookson WO, Braun-Fahrlander C, et al. Exposure to environmental microorganisms and childhood asthma. N Engl J Med 2011;364(8):701-709.
15. D'Amato G, Bergmann KC, Cecchi L, Annesi-Maesano I, Sanduzzi A, Liccardi G, et al. Climate change and air pollution: Effects on pollen allergy and other allergic respiratory diseases. Allergo J Int 2014;23(1):17-23.
16. Baldacci S, Maio S, Cerrai S, Sarno G, Baïz N, Simoni M, Annesi-Maesano I, Viegi G; HEALS Study. Allergy and asthma: Effects of the exposure to particulate matter and biological allergens. Respir Med. 2015 Sep;109(9):1089-104. doi: 10.1016/j.rmed.2015.05.017. Epub 2015 May 22. Review. PubMed PMID: 26073963.
17. Annesi-Maesano I, Baiz N, Banerjee S, Rudnai P, Rive S, SINPHONIE Group. Indoor air quality and sources in schools and related health effects. J Toxicol Environ Health B Crit Rev. 2013;16(8):491-550. doi: 10.1080/10937404.2013.853609. Review. PubMed PMID: 24298914.
18. Bentayeb M, Simoni M, Norback D, Baldacci S, Maio S, Viegi G, Annesi-Maesano I. Indoor air pollution and respiratory health in the elderly. J Environ Sci Health A Tox Hazard Subst Environ Eng. 2013;48(14):1783-9. doi: 10.1080/10934529.2013.826052. Review. PubMed PMID: 24007433
Last updated: 03 December 2015
Brief descpription of the European Pollen Map project, under implemention by the Aerobiology & Pollution IG.
For the 30 million European citizens, who have seasonal allergies, rising pollen counts in the spring bring symptoms that can ruin a time of year the rest of us enjoy immensely.
Allergy symptoms are not only annoying, but for many people interfere with their ability to work, perform at school, or even sleep. Understanding the significance of pollen and fungi spore counts can help to better manage symptoms.
Pollens and fungi represent the clinically most important outdoor allergens. Researchers are interested in pollen and fungus sampling because these airborne allergens occur in easily identifiable units.
Attempts at counting pollens go back over 100 years. Initial investigators collected particles on an adhesive coated slide. However, variables such as wind speed and particle size changed the number of particles coming to rest on a slide, affecting the accuracy of this method.
More recently, researchers have developed volumetric techniques that measure the concentration of pollen grains or fungi spores in the air. This gives them a better estimate of how much pollen people in the sampling area are being exposed to.
The Interest Group on Aerobiology and Pollution has a project and a “dream” to build a project named European Pollens Map, which aim is to provide information on pollens to the members of the European Academy of Allergy and Clinical Immunology (EAACI), as well as to the public in general and to allergic patients throughout Europe, on the internet.
Our projects needs:
1. Collaboration of all European Allergy National Societies to gather information on:
a. Number of pollen stations in each Country
b. Selection of stations that use pollen samplers with similar characteristics. An ideal air sampler would be of the Hirst type.
c. Amount and type of pollens per weekly period. If this is not feasible, provide at least weekly data in the Spring and monthly data in the remaining months
d. To find an element of functional interlink between the Interest Group on "Aerobiology and Pollution" and each of the scientific societies. Whenever possible this element should be a member of EAACI.
e. To develop an informatics software system, such as a database on Excel format, where each station or each scientific society can upload the data, which will subsequently be added to the EAACI central server.
The EAACI website should have a dynamic tree structure with several pages, each page relating to a different subject, in a modular way to develop:
a. General information on allergies.
b. Data on the effects of pollination and allergies.
c. Characteristics of the allergic diseases that are more frequently related with pollens.
d. Characteristics of each pollen type, cross-reactivity among several species and power to induce allergies..
e. Images of the several types of pollens captured in the atmosphere and their implication in the allergies.
f. Amounts and types of pollens for each Country. Ideally, there should be a map of Europe and, with a simple click on a Country, the software should provide the data on that Country. Considering that each Country has several regional areas with different data, these should be accessible by region.
g. The amounts of pollens should appear in 3 different colours (red, yellow and green, for instance) according to the degree of the patients allergies
h. The levels of severity on pollination will be defined by the scientific committee of the IG group.
i. Information about the meteorological situation, with weather forecasts and weekly periodicity. This should easily work with connection to one of the satellites existent in Europe. .
j. The meteorological data, together with the pollinic data, will provide forecasts for next few days, or next week.
k. Weekly, monthly and yearly graphs showing the different pollen types, and those that more frequently cause allergies. Up to 20 types will be considered. Each pollen type should have its page, with the individual characteristics and statistical data on previous years.
l. Global page with an annual pollen calendar for Europe and for each Country.
m. A Forum area for IG members and other medical institutions should be provided.
n. Contact area through e-mail in each of the Countries integrating the European Network.
Finally we believe we can have some advantages such as:
1. Establishment of functional interlinks among the several European Allergy Societies;
2. Functional Interlinks among the community to share information in the area of the Aerobiology through the Forum;
3. The pages will be generated starting from a database;
4. It is possible to maintain the data obtained through research for subsequent viewing;
5. Technical information service for physicians in general and for allergists in particular
6. Information service for patients in general and for allergic patients in particular;
7. Real-time information for patients with pollinosis regarding the pollen levels in the residence area or in the place where someone intends to travel;
8. Possibility of easy up-grading (ORACLE or Windows).Last updated: 07 November 2014
Summary of Current Activities and Future Plans: The IG’s current and 2008 activities: 1. The second PGC “hands-on” on Aerobiology has been held in Barcelona last June and it was fully self-financed, being microscopes renting paid by a sponsor and pollen trap use and expedition paid by Lanzoni. 2. The first kick-off meeting of the Task Force EAACI-ERS (European Respiratory Society) on the “Effects of Climate change on respiratory allergic diseases and on asthma prevalence” has been held in Barcelona the 8th of June. Some decisions have been taken and some documents are in preparation. The next meeting will be held in Berlin the 5th of October 2008 in the framework of the ERS annual meeting. 3. Both Chairman and Secretary joined meetings as invited speakers, always mentioning IG activities. 4. Secretary joined the scientific committees of the 3rd International Meeting on Molecular Allergology (ISMA) in Salzburg and of the 1st International Meeting on Ragweed in Budapest. 5. Secretary (as Italian delegate) is involved in the management committee of the COST Action ES0603: “Assessment of production, release, distribution and health impact of allergenic pollen in Europe (EUPOL)” financed by EU Framework Programme. 6. IG served as platform for submitting an important European project on detection of allergens in ambient air. The project passed the first selection and it is under further revisions. A supporting letter from EAACI ExCom has been requested. The IG’s future plans for 2009: 1. To finalize the final documents of the Task Force within June 2009, in order to submit them to the ExComs and, then, to scientific journals (possibly Allergy and ERJ) 2. To organize the third PGC on Aerobiology for London 2010. 3. IG will be continue to be involved (through personal participation of Secretary as national delegates) in the COST EUPOL, looking for possible collaborations and common activities. 4. To plan a summer school for 2010 on “Environmental Allergology” (tentative title) to be organized in collaboration with the COST EUPOL which already officially approved the proposal, providing and supporting speakers and students. 5. To collect information about studies done inside EAACI context about Aerobiology and Pollution. 6. To promote having at least one EAACI member per national society member inside the Interest Group, to share information regarding pollution and pollinosis among different countries. 7. To connect with indoor allergen studies with other IG and Section of EAACI 8. To continue participating in the contents of the EAACI website with texts and information and deliver it ready for colleagues and patients over the EAACI websiteLast updated: 03 June 2009
Clinically important of pollinosis is primarily due to flowering plants with wind dispersed pollens. Although these anemophilous species form a minority of flowering plants, they produce prodigious amounts.
Entomophilies (insect pollinated) plants produce relatively few pollen grains. Plants having only a portion of their pollen grains airborne are termed amphiphilous. Their role in Pollinosis is not clear. The pollen producing organs, stamens, consist of an anther attached to a filament. Allergenic pollens develop in and are released from pollen sacs contained in the anthers. Pollen sacs are lined with a nutritive cell layer, the tapetum. During its formation, each immature pollen grain secretes about itself a clear layer, the intine. Around this the tapetum deposits a multi layer exine composed of a polymer, sporopollenin. Release of pollen from the anther is known as anthesis. Drying creates gaps in the anther wall through which pollen escapes. Airborne pollen levels tend to increase during warm, dry, clears conditions and fall during cool, moist periods. Although pollen grains can travel several hundred miles, concentrations of windborne pollens generally decrease sharply within a few hundred meters of their source.
Intact pollen grains are presumed to be the primary carriers of allergen, but ragweed allergens have been associated with particles < 5 gm, and Amb a 1 (antigen E) activity has been found in submicronic particles. Pollen allergens can be extracted from the somatic portion of ragweed plants and may become airborne in vegetable debris. Furthermore, allergens might be eluted from pollen grains deposited ort moist surfaces, with dispersion of the resultant extract in droplets.
Air sampling relies on recovery of pollen grains for microscopic evaluation. As air sampled we are using volumetric devices like those which catches wind oriented spore, such as Lanzoni or Burkard traps, which are among the most versatile collectors for a variety of particles, including pollens. These devices also are especially useful for collecting fungal spores and other agents well below 10 ìm. Samplers should be placed on an unobstructed rooftop. Sampling closer to the ground sometimes reveals exposures not reflected by rooftop samplers. Personal collectors using small filters and compact pumps can determine individual exposure patterns. High volume samplers with fibreglass filters have been used to collect aerosols that can be extracted for immunochemical analysis. This sampling may provide a better overall view of total allergen exposure.
Most airborne pollens range in size from 12 to 70 mm. Trees and other woody plants are the earliest to undergo pollination each growing season. Tree pollination especially varies in date and intensity. Non-woody perennial species (e.g., grasses) generally follow the trees from late spring to midsummer. In southern and west coast areas, grasses may pollinate throughout much of the year. Anemophilous annuals (e.g., ragweed) generally shed pollen in midsummer to late summer, depending on their seed germination dates.
Establishing a dose response relationship between pollen exposure and symptoms is difficult. The range of severity for individuals is quite broad, and symp¬toms often reflect concurrent exposure to several al¬lergens. Response usually increases with ongoing short term exposure (priming), and exposure involves aerosol fractions besides intact pollen grains. Pollens usually penetrate to the level of the glottis. Most de¬posit in the nose, pharynx, oesophagus, stomach, and eyes.
The protein molecules in pollens capable of sensitising patients generally range in size from 10,000 to 40,000 Daltons. Once the pollen grain is in contact with the upper airway mucous membranes, symptoms develop within a few minutes, suggesting that these proteins are rapidly eluted. Although individuals are exposed to many potentially allergenic pollens, only a relatively few pollens produce symptoms.
In the Urticaceae and Asteraceae families, nettle and pellitory show a lack of cross allergenicity. A 12,000 dalton allergen has been purified from pelli¬tory. Among the composites, major allergens have been identified from the tribe Ambrosicae. The most important is Ambrosia artemisia (short ragweed) allergen Amb a 1 (antigen E). Other purified antigens include Amb a 11 (antigen K), Amb a 111 (Ra3), Amb a V (Ra5), and Amb a VI (Ra6). Several other aller¬gens have been partially characterized. Some anti¬genic differences exist between giant and short rag¬weed species. In areas where Asteraceac other than ragweed are clinically significant, adequate immu¬notherapy will not be achieved by using ragweed ex¬tracts alone if pollen levels are significant.
The Chenopodiaceous and Amaranthaceae families contain major inducers of pollinosis in the western United States. An antigen from Russian thistle (Sal p 1) has been isolated. Members of the Chenopodiaceous are closely related and cross react strongly with the amaranth family. Russian thistle, however, appears to contain potent allergens (some of which are unique) that require special treatment. Russian thistle may provide relevant materials for some of the other chenopods, such as lamb's quarters, but generally chenopods of local significance require indi¬vidual therapy.
There are pollen productions over all months, however on spring the pollens concentration in the air in Europe, released from trees, weeds, and grasses, which rides on currents of air, enter human noses and throats, triggering a type of seasonal allergic rhinitis with several symptoms such as sneezing, eye and nasal itching, rhinorrea, etc. Of all the things that can cause an allergy, pollen is one of the most widespread. Many of the foods, drugs, or animals that cause allergies can be avoided to a great extent; even insects and household dust are escapable. Short of staying indoors when the pollen count is high and even that may not help, there is no easy way to evade windborne pollen.
Allergic Rhinitis is the most common of the allergic diseases and refers to seasonal nasal symptoms that are due to pollens.
Plants produce microscopic round or oval pollen grains to reproduce. In some species, the plant uses the pollen from its own flowers to fertilize itself. Other types must be cross-pollinated; that is, in order for fertilization to take place and seeds to form, pollen must be transferred from the flower of one plant to that of another plant of the same species. Insects do this job for certain flowering plants, while other plants rely on wind transport. Most allergenic pollen comes from plants that produce it in huge quantities.
Grasses and trees, too, are important sources of allergenic pollens. Although more than 1,000 species of grass grow in Europe, only a few produce highly allergenic pollen. These include timothy grass, poa, phleum pratense, bluegrass, grass, Bermuda grass, redtop grass, orchard grass, and sweet vernal grass. Trees that produce allergenic pollen include birch, olive, oak, ash, hickory, pecan, box elder, etc. Also in Southern European countries nettle and pellitory of the wall are produced in larges quantities and provoke sensitisation to a higher number of patients, who have allergic rhinitis or even asthma.
It is common to hear people say that they are allergic to colourful or scented flowers like roses. In fact, only florists, gardeners, and others who have prolonged, close contact with flowers are likely to become sensitized to pollen from these plants. Most people have little contact with the large, heavy, waxy pollen grains of many flowering plants because this type of pollen is not carried by wind but by insects such as butterflies and bees.
One of the most obvious features of pollen allergy is its seasonal predominance.
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.
A pollen count, which is 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 in the air in a certain area at a specific time. It is expressed in grains of pollen per square meter of air collected over 24 hours. Pollen counts tend to be highest early in the morning on warm, dry, breezy days and lowest during chilly, wet periods. Although a pollen count is an approximate and fluctuating measure, it is useful as a general guide for when it is advisable to stay indoors and avoid contact with the pollen. Please contact your national Aerobiology Network or an European network, such as the European Aeroallergen Network (E.A.N.).
Information to Patients
Last updated: 07 November 2014
- There are several things that can be done against pollen allergies. The first and most effective is to avoid or minimize the contact with the allergen, such as pollen
- Avoid outdoor activities
- Avoid outdoor activities when the pollen count is high. Walks in the garden, mowing the lawn, camping or outdoor sports will increase exposure to pollens and the risk of allergy.
- Keep windows closed while driving. This will dramatically cut exposure to pollens. Cyclists should wear closed-visor helmets. Keep windows closed at home when the pollen count is high.
- Wearing dark classes whenever you are outside is an efficient and practical way to avoid eye problems.
- Take the medicine prescribed for you.
- Medication is the most efficient way to fight allergy symptoms. Make an appointment with a trained Clinical Immunologist for a correct diagnosis and the prescription of the most suitable medication.
- Prevention might be achieved via anti-allergy vaccines.
- No physical exercises outdoors during the pollen season
- Avoid alcohol beverages
- Wear sunglasses, which prevent to some extent your eyes from pollen contact and protect them.
- Schedule your holidays: to avoid contact with specific pollen you are allergic to, schedule your holidays in places with a low pollen count, for example snow or beach holidays. The Pollen Bulletin will tell you the high pollen season.
View the 2004 allergy pollen distribution of ragweed, grasses and pellitory of the walll in Central, Southern and North Europe.Last updated: 01 December 2009
Key words: Allergenic pollens; Outdoor air-pollution; Pollinosis; Respiratory allergy; Seasonal allergy.
Division of Pneumology and Allergology
Azienda Ospedaliera ad Alta Specialità A. Cardarelli Napoli Italy
Rione Sirignano, 10
(Riviera di Chiaia)
80121 Napoli Italy
Address for correspondence:
Prof. Gennaro D’Amato
Director, Division of Pneumology and Allergology
Via Rione Sirignano,10
80121 Napoli, Italy
Fax +39 081 7473331
Leaning on two servants, he brought himself upright and immediately collapsed again, I suppose because his breathing was affected by the dense fog that obstructed his airways that were of a weak nature, narrow and subject to inflammation.
Plinius the Younger- Letter to Tacitus (1)
It is to Plinius the Younger that we owe the first description of a fatal respiratory disorder induced by natural air pollution. The patient was Plinius the Elder, head of the Roman fleet, who had moved to Pompeii in the Bay of Naples (Italy), to observe the eruption of Mount Vesuvius and to help Pompei inhabitants in the year AD 73.
We do not know if Plinius the Elder experienced allergic bronchial asthma, but more than 2000 years later, millions of people in the nearby city of Naples are inhaling high levels of photochemical smog and many of these are affected by respiratory allergic disorders mainly induced by pollens of Parietaria the Pellitory-of-the-wall, which grows abundantly in the city (2, 3).
Pollen allergy has a remarkable clinical impact all over Europe and there is a body of evidence suggesting that the prevalence of respiratory allergic reactions induced by pollens in Europe is on the increase, a trend that is clearly evident also in the Mediterranean area (3-7). Since airborne-induced respiratory allergies do not recognise national frontiers, and like most diseases that can be prevented by avoiding exposure to the causative agent, the study of pollinosis cannot be limited to national boundaries. In Europe, the main pollination period covers about half the year, from spring to autumn, and the distribution of airborne pollen taxa of allergological interest is related to five vegetational areas (Table I).
Because of its climatic conditions, characterized by mild winters and sunny days with dry summers, the vegetation of the Mediterranean area is different from that of central and northern Europe. Allergenic-pollen-producing plants typical of the Mediterranean climate are Parietaria, Olive and Cupressaceae. However, during the last thirty years or so, aerobiological and allergological studies have been developed rapidly in most parts of Europe and also in Mediterranean area. This has led to an increased density of observational networks of pollen-counting stations, and also to the need for multilateral exchange and cooperation in aerobiological and allergological studies.
The allergenic content of the atmosphere varies according to climate, geography and vegetation. Data on the presence and prevalence of allergenic airborne pollens, obtained from both aerobiological studies and allergological investigations, make it possible to design pollen calendars with the approximate flowering period of the plants in the sampling area. In this way, even though pollen production and dispersal from year to year depends on the patterns of preseason weather and on the conditions prevailing at the time of anthesis, it is usually possible to forecast the chances of encountering high atmospheric allergenic pollen concentrations in different areas.
Aerobiological and allergological studies show that the pollen map of Europe and of Mediterranean area is changing also as a result of cultural factors (for example import of plants such as birch and cypress for urban parklands) and greater international travel (e.g. the colonization by ragweed in France, northern Italy, Austria, Hungary etc.).
By virtue of aerobiological sampling of the pollen content of the atmosphere of various Mediterranean cities, three pollen seasons have been identified (3, 6, 7): a low winter pollen season (from December to the end of March) marked by the presence of the pollens of such trees as Cupressaceae (Cupressus and Juniperus), Corilaceae (Hazel), Acaciae (Mimosa) and some Betulaceae.
A high spring-summer pollen season (from April to July), of marked allergological interest, dominated by the pollination of Grasses, Parietaria and Olea (Olive). Slightly overlapping this season, from March to May, Platanus flowers, and has some allergenic importance in some Mediterranean areas as Southern France, Spain etc.
A summer-autumn season (from August to October) marked by the second, less pronounced, peak of Parietaria and sometimes of Gramineae and the pollens of herbaceous plants, such as mugwort (Artemisia) and Chenopodiaceae.
Grass pollen is by far the most important cause of pollinosis throughout the European continent and also in the Mediterranean area. It is interesting to note that in various European cities, whilst the prevalence of allergic rhinitis and allergic asthma is increasing, the atmospheric concentration of grass pollen is decreasing (3,8). The decrease in grass pollen concentrations has been attributed to substantial decreases in the area of grassland over large areas of the continent. In fact, the last 25 years have seen a reduction in grassland of about 40% (8). However, the observation that cases of allergic rhinitis and asthma induced by grass pollen are increasing is probably related to various factors, including increased air pollution (8-10).
Parietaria is a genus of the Urticaceae family, and P. officinalis and judaica are the most common allergenic species of this genus.
P. judaica grows in coastal Mediterranean areas such as Spain, southern France, Italy, Yugoslavia, Albania, Greece .This allergenic plant, which is responsible for many cases of severe pollinosis, has two very long flowering periods. Its pollen appears first at the beginning of the spring and persists during the spring and summer months, often reaching a peak level with daily mean values of more than 5 hundred pollen grains per cubic meter of air at the end of April or in May, depending on the climate of the area. A shorter pollination period is observed from the end of August to October.
In the Oleaceae family, the most allergenic pollen is produced by Olea europaea, the olive tree, which in the Mediterranean area has been recognized as being one of the most important causes of seasonal respiratory allergy (11). The olive pollination season lasts from April to the end of June and sometimes causes severe symptom (rhinoconjunctivitis and/or bronchial asthma). Olive tree, like Birch, has reproductive rhythms of high and low years for the abundance of pollen and subsequent seed. The alternating patterns may be modified or even obscured by the influences of weather during the times of pollen formation and dispersal.
Frequently the sensitization to pollen allergens of Olea is associated with other atopic sensitizations such as allergy to grasses and it is frequently difficult to know whether sensitization to grasses prevails or whether it is Olive that prevails.
Another interesting aspect of olive allergy is that in subjects with sensitization to the allergens of this pollen the clinical symptoms are frequently not limited to the pollination season (May-June) but are present all year round without an explanation.
As for Birch, which is the most potent of the pollen-allergen-producing trees in northern Europe, this arboreal plant is spreading down into the Mediterranean area. For example Birches are becoming increasingly abundant in northern Italy where landscape artists tend to use them in new urban parks. The typical peaks of birch pollens are recorded in northern Europe during May, whereas in southern Europe the birch pollen concentration generally peaks in April. This tendency for spring-pollinating plants, like birch and grass, to flower earlier in the warmer southern regions of Europe is reversed for the Autumn-pollinating types such as mugwort (3).
Cypress pollination is characterized by a wide variability with very high concentrations in Mediterranean coastal areas, where it frequently induces rhinoconjunctivitis. This pollen taxa is the most common airborne allergen of the winter months in some Mediterranean cities.
The increasing epidemiologic impact of pollinosis induced by Cupressaceae plants is related to the increasing use of these species for gardening and reforestation (12). So again, like with birch, we have a case of fashion influencing the epidemiology of pollen-induced disorders.
Pollen grains from herbs like mugwort (Artemisia) and Plantain (Plantago) are of limited but, nevertheless, real clinical importance. Mugwort in particular has a marked sensitizing capacity. In the same Compositae family of mugwort, we find also ragweed (Ambrosia), which is colonizing Europe, and not only Central Europe, but also some parts of the Mediterranean area such as northern Italy.
Interaction between urban air pollution and pollen allergy
Studies have demonstrated that urbanization and high levels of vehicle emissions and westernised lifestyle is correlated with the increasing frequency of pollen-induced respiratory allergy and people who live in urban areas tend to be more affected by pollen-induced respiratory allergy than those of rural areas (13). In urban cities of the Mediterranean area among the components of air pollution there are frequently high concentrations of ozone favoured by sunny days and ultraviolet radiations. In particular ozone trends depend not only on substrate supply (emissions of nitrogen dioxide by cars), but also on weather conditions and sunny days facilitate the transformation of nitrogen dioxide into ozone, thereby producing the so called “Los Angeles smog”.
There is a growing body of evidence that components of air pollution interact with inhalant allergens carried by pollen grains and may enhance the risk of both atopic sensitization and exacerbation of symptoms in sensitized subjects (14, 15), since urban air pollution affects both airborne allergenic pollen and the airways of exposed subjects.
Pollen allergy has been one of the most frequent models used to study the interrelationship between air pollution and respiratory allergic diseases. Pollen grains or plant-derived paucimicronic components carry allergens that can produce allergic symptoms (15, 16). They may also interact with air pollution (particulate matter, ozone) in producing these effects. (Table II). Furthermore airway mucosal damage and impaired mucociliary clearance induced by air pollution may facilitate the access of inhaled allergens to the cells of the immune system (14-16) (Table III). In addition, vegetation reacts with air pollution and environmental conditions and influence the plant allergenicity. Several factors influence this interaction, including type of air pollutants, plant species, nutrient balance, climatic factors, degree of airway sensitization and hyperresponsiveness of exposed subjects. The city of Naples serves as a good model with which to study the interaction between pollen-derived allergen and air pollution. It has about 2 million inhabitants and very dense traffic. It is located in a coastal area enclosed on three sides by hills and mountains. The year-long sunny days favour high levels of ozone. This situation, on days with absence of wind and rain, favours critical episodes of air pollution. The climate also favours the pollination of Parietaria, which grows in abundance throughout the city (2, 6). About 30% of inhabitants are allergic to this plant and more than 50% of these Parietaria pollen-allergic subjects experience bronchial asthma and its equivalent, with high level of bronchial hyperresponsiveness (2, 6, 15 ).
During spring the prevalence of Parietaria-induced allergic respiratory disorders tends to increase and there is a peak in the number of emergency room visits for allergic asthma attacks when there is an increase in airborne concentrations of Parietaria pollen grains and a parallel increase of ozone levels from April to June. This parallel increase usually starts in February and peaks between May and June when Parietaria pollen grains reach levels of about 1000 grains/m3 of air. After July the production and release of Parietaria pollen usually decreases, while ozone levels remain high also in autumn during which the concentration of Parietaria pollens is low. There is also a diurnal correlation of both peaks, since Parietaria pollen and ozone reach their highest levels in morning. Parietaria peaks earlier than ozone because of the time required for the photochemical reaction to develop.
So, the conditions of Naples favour the interaction between Parietaria pollen, ozone and inhalable PM and on sunny days in the atmosphere of Naples there is a parallel increase of ozone, PM10 and of Parietaria pollen grains. This parallel increase usually starts in January or February and the increasing trend reaches June or July. At this time the production and release of Parietaria pollen usually decreases, while ozone and PM10 are high also in autumn and frequently also during winter.
References1) Plinius the Younger. Letter to Tacitus (letter VI.16).105 AD.Rome, Italy.
2) D’Amato G, Dal Bo S, Bonini S. Pollen-related allergy in Italy. Ann Allergy 1992;68:433-437.
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Review article published in Allergy
Pollen allergy in EuropeLast updated: 07 November 2014
A first observation on Thunderstorm-associated asthma in the Mediterannean area by the Aerobiology and Pollution IG Chairman.
People affected by pollen allergy should be particularly alert to the danger of being outdoors during a thunderstorm in the pollen season.
Six adults and a girl of 11, experienced severe asthma attacks - nearly fatal in one case – during a thunderstorm in Naples, Italy on June 4, 2004. All patients received treatment in emergency departments, where it was registered that four of them had a history of asthma and the other two a history of rhinitis. None of them were taking antiallergic and/or antiasthma drugs on a regular basis at the time when the thunderstorm struck.
It is interesting to note that all patients were outdoors at the time of the thunderstorm and, according to the findings of Pr.G. D’Amato, EAACI Aerobioloy & Pollution IG Chairman, and his research team at the "Cardarelli” Hospital in Naples, the allergic respiratory symptoms of all seven patients were due to exposure to Parietaria pollen, an Urticarea widely spread in the Naples area. According to the pollen diary, the concentration of airborne Parietaria pollen grains was particularly high - a peak of 144 grains/m3 being recorded on June 3. However, air pollution levels were not particularly high on June 3rd and 4th.
Full article is published at BMJ Q & A Archive.Last updated: 07 November 2014
Evidence suggests that allergic respiratory diseases such as rhinitis and bronchial asthma have become more common over the last few decades. Why this is so, has yet to be established. Among the factors implicated in this ''epidemic'' there are the followings:
- Better diagnosis: more patients with positivity to allergological tests
- Modern lifestyle: increased exposure to household irritants
- Reduced incidence of infections with a switch of T cells from Th1 to Th2
- Increased mobility with consequent exposure to new allergens
- Increased indoor and outdoor airborne pollutants.
Allergic respiratory diseases are known to be genetically determined. Therefore, the dissection of the relative contribution of environmental and genetic factors will provide a deeper understanding of the pathophysiology underlying the trends in allergic diseases.
Drastic environmental modifications have been targeted as the mean culprit for the rise. However, to induce an atopic- allergic sensitization, the environmental factors act in this way
EAACI-2-NapoliLast updated: 07 November 2014