Search

Pollen is a major cause of allergy and monitoring pollen in the air is relevant for diagnosis, treatment and prevention, as well as for biomedical and biological research. Many aero-biological studies have been conducted all over the world to ascertain aerial concentrations and seasonality of pollen grains.Monitoring of airborne biological particles is carried out by various gravimetric, impaction, and suction sampling devices. The Hirst trap, later modified to Burkard(®) or Lanzoni(®) traps, is the most widely used sampler. Counting and identifying pollen grains is then performed under optical microscopy. Based on differences in airborne pollen recorded over several years of observation, pollen calendars have been drawn up as aids to allergy diagnosis and management but they could be replaced advantageously by allergy-risk calendars. Pollen counts also provide valuable information about the geographical origin of pollen grains.Since the identifying and counting of pollen grains in ambient air samples is still a demanding and time-consuming task, there is an increasing interest in the automation of pollen monitoring. Furthermore, the divergence sometimes observed between clinical observations and pollen counts provides an incentive to collect aero-allergens directly. Lastly, pollen monitoring could be improved through the use of personal bioaerosol samplers.Great progress has been made in aerobiology for over a century, but much remains to be accomplished, particularly in relation with the standardization of methods.

The pollinic season of ambrosia in 2003 present strong disturbances due to the meteorology of the end of this summer. The areas with the allergenic risk are concentrated on the area of Rhône-Alpes (more than 40 days with a risk equal to or higher than 3) and on the peripheral areas: the area Centre Auvergne with Saint Etienne, Clermont-Ferrand and Montlucon with approximately 10 days with a the allergenic risk equal to or higher than 3; the Saône-Savoie area with the towns of Macon and Grenoble with about twenty days with a allergenic risk equal to or higher than 3 and Dijon, Châlon-sur-Saône with 6 days with a allergic risk equal to or higher than 3; the Mediterranean area with the towns of Avignon and Aix-in-Provence presenting ten days with allergenic risk equal to or higher than 3, Marseille and Toulon with 7 days with a allergenic risk equal to or higher than 3. The allergic risk related to the ambrosia in 2003 had peaks overall less high, but the season is spread out and had during until September 20. The daily peaks for the Rhône-Dauphiné-Drôme area were noted between 6 h and 8 h or 8 h and 10 h, for 2003. On the peripheral areas, we remark a diversity of the daily peaks (Châlon-sur-Saône between 18 h and 20 h). Are these pollens local grains or immigrants grains? On Lyon I (Gerland), the follow-up of the data of the ambrosia since 1987 permit to remark a stagnation of the number of days with an allergic risk, despite a reduction of the number of pollens.

Currently, two techniques of analysis are classically used by the aerobiological networks: the technique of the 12 vertical lines allow to follow the evolution by bi-hourly periods of pollination, but the segmentation of the sample doesn't allow to visualise pollen clouds of short duration; the technique of 2 or 3 horizontal lines allow to follow the daily evolution, but only the daily totals are recorded. The MICROVISION system adapted by the RNSA to the pollen analysis allow to keep the horizontal method, which is faster and continue, and to record automatically in the database the hourly or bi-hourly data. So each pollen is recorded by its coordinates with a precision of 1 micron (1.8 seconds). First, we realised a cartography of the impaction of the pollen grains on the strip, in order to locate the more representative horizontal lines. Secondly, the coupling of the microscope with the Microvision system and the software of data acquiring elaborated by the RNSA allow to propose a more reliable and faster procedure for pollen analysis.

The pollen of Ambrosia, highly allergenic, can be found in high quantities in the French regions of Burgundy, Auvergne and mostly a great part of the Rhône-Alpes region. The aim of this study was to establish some forecast models of the Starting Date of the Pollen season (SDP) of Ambrosia, in order to provide early information to allergists and allergic people. The pollen data came from the Hirst trap set up in Lyon since 1987 by the RNSA, and the meteorological data for the same period were provided by Météo-France. Two models were used, a sum of daily average temperatures and a multiple regression on all the 10-day period meteorological data. The results were quite accurate, except for 2003 with the temperature sums, probably because of very special meteorological conditions. So the models will have to be updated in this way.

The principal objective of the French aerobiology Network (RNSA) is to provide to the doctors, the authorities of health and general public, information on the allergic risk related to pollens. To provide only information on the pollinic contents of the air is not sufficient, it acts of past information which can only contribute to the comprehension of some symptoms. On the other hand, by using these last pollinic data, of clinical information present and weather forecasting, it becomes possible to establish information on the Allergic Risk related to such or such pollen, or their whole for the days to come. Thus the RNSA, with more than fifteen years of data of pollinic and clinical present information, could establish correlations enabling him to provide an index of allergic risk going from 0 to 5 (0 = no one; 1 = very weak; 2 = weak; 3 = average; 4 = high; 5 = very high) dependent of: the pollinic accounts, the geographical situation of each site, the weather forecasting for each site, the period of the year, the type of taxa etc. This index makes it possible to provide information accessible to all and useful for the situation present and to come.

The french network of aeropalynology includes traps very close together and vast areas without any trap as well. A study was launched in order to optimise this network, without the number of traps increasing too much. Five criteria are successively reviewed to rationalise the spatial cover. Equi-distance of sites has to be balanced by the number of concerned people. But the need for having long time series is incentive to delete only as a last resort the traps which are reliable for a long time. Moreover, apart from the general network, some local or regional features make indispensable a trap in such-and-such a place (health resort), or justify a higher density of traps in such-and-such an area (the Rhône-Alpes concerning ragweed, the Mediterranean South concerning cypress).

Ragweed in France is a rather recent pollen which causes strong allergies on the populations concerned. This pollen, mainly located in the area Rhone-Alpes, extend more and more on totality of France. Indeed, the pollinic data highlight the presence of ragweed on all the territory with very low, as for Brittany, to several hundreds grains in the area of Rhone-Alpes. So four towns of this area have followed closely the extend of this pollen during the year 2002 through five pollen-traps (2 for the town of Lyon). The trap of Lyon I (Gerland) made it possible to follow temporal the extend of ragweed from 1987 to 2002 and the increase of the number of grains as that of the number of days with a significant allergic risk. The study shows also the differences in quantity of pollens, the differences between the daily allergic risks of the five sites, as well as the differences, between the cities, of the number of days when the allergic risk is significant. It is necessary that pollen of ragweed can be followed closely because of its strong allergenic capacity, in the area of Rhone-Alpes, where the plant prevails mainly, but also on the totality of the own territory, this to supervise its evolution and the speed of proliferation of the plant.

It was traditional until these last years to supervise the evolution of pollination by taking account only of the evolution of the number of grains of pollens present per m3 of air per year on each site. If this factor is significant, it is not sufficient. Indeed, it is essential to be able to supervise the evolution of the number of days in the year when the allergic risk related to a pollen is significant. The work which is presented shows over the years 1992 to 2002, for some sites of the RNSA (Amiens, Paris, Rouen, Strasbourg, Montlucon, Bordeaux, Lyon, Marseille, Toulouse) that there can be parallelism of the curves "pollinic counts" and "allergic risk", but also of light discordances. Should a thorough study of the dates of appearance supplement this work because these modifications can be the consequence of the climatic motions of these last decades.

The aim of this study was to determine the main characteristics of the Poaceae pollen season in France (seasonal and daily quantities) in 2001, and to compare them to those of the previous years. The data came from seven volumetric Hirst traps, located in the cities of Amiens, Paris, Lyon, Nîmes, Bordeaux, Montluçon and Strasbourg. The study period range from the beginning of March to the end of August. The pollen quantities of 2001 were particularly high in three sites (Montluçon, Bordeaux et Lyon); they were higher than those of 2000 in Amiens and Strasbourg, but in those sites the peak of the whole series was situated in 1994; lastly the pollen quantities of 2001 were little different or lower than those of 2000 in Nîmes and Paris. This was probably not without effect on allergic people.

Within the framework of the decrees taken on the departments of Isère and Rhone concerning the protection of the population with respect to ambrosia, the object of this study is to relate the analysis of the daily pollen counts in the of air along the Lyon-Grenoble axis. With this intention, three sensors of the type HIRST were positioned according to standards of the European networks in Lyon-Gerland, Bourgoin-Jallieu and Grenoble. The results presented show the curves of the daily pollen counts on the three sites and by indicating the allergic thresholds of risks associated defined by the RNSA. The number of days with high risk, for each of the three sites, can thus be compared. Experiment must be prolonged to follow, these comparative results and moreover, possible effectiveness of the obligations of pulling up of the plant on atmospheric pollination.

Marseille has two sites (Centre and North) where airborne pollens are collected and counted. The most numerous pollens are from Cupressaceae Taxaceae. We compared the quantities collected with both pollen traps during February, March and April 1988 and 1989. Most of pollinization takes place in March. In Marseille's Centre, there were three times more trapped pollen during 1989 than in 1988. In 1989, there was 40% more pollen on northern site as compared with the other one. As indicated in 1989 with both sites, it suggests a circadian periodicity of Cupressaceae Taxaceae pollen: their highest count is usually between 9 and 11 hours a.m.

The permanent recording of air pollen contain from more than 25 sites distributed all over France using the same method gives homogeneous results with every two hours daily measures. Among usual pollen taxa harvested in the city of Lyon, Ambrosia pollen data is to be emphasized due to its high allergenic potency. Between years 1987 and 1990, Ambrosia pollen data observed in Lyon have been recorded and completed with data obtained from other places in France where Ambrosia is also to be found during the summer and autumn seasons. Significant annual variations have been observed while the daily repartition of records appear quite steady. Data obtained do emphasize the high allergenic potency of Ambrosia of air pollen origin in a great number of french regions.