Acute effect of air pollution on respiratory complaints, exhaled NO and biomarkers in nasal lavages of allergic children during the pollen season.

During 2 months of the pollen season, the acute and putative adjuvant effect of traffic-related air pollution on respiratory health was investigated in children sensitised to grass pollen or house dust mite (HDM). Respiratory complaints were objectified via measurement of exhaled NO and inflammatory mediators in nasal lavage (NAL). During the study children, skin prick negative (n = 31) or positive to grass pollen (n = 22), HDM (n = 34) or grass pollen + HDM (n = 32), kept a daily diary on respiratory symptoms, and NAL and exhaled air was sampled twice a week. The level of air pollutants and pollen was monitored continuously. Like children sensitised to HDM, those sensitised to pollen reported respiratory complaints (shortness of breath, itchy eyes or blocked nose) more frequently than non-sensitised children during (but not before) the pollen season; the respiratory complaints of sensitised children were independent of the pollen level. In addition, exposure to increased levels of PM(10) induces 'shortness of breath' in pollen- and HDM-sensitised children, whereas ozone induces a blocked nose in HDM-sensitised children. Combined exposure to PM(10) + pollen and O(3) + pollen induces a blocked nose in both HDM-sensitised children and children sensitised to pollen + HDM. Significant positive associations were found between eNO and the levels of NO(2), CO, PM(2.5) and pollen in both sensitised and non-sensitised children. At the start of the pollen season, the NAL concentration of eosinophils and ECP in pollen-sensitised children was increased compared to winter, but their levels were not further affected by increased exposure to pollen or air pollution. In conclusion, during the pollen season, sensitised children continuously report a high prevalence of respiratory complaints which coincides with increased levels of upper and lower airway inflammatory markers. No additional pro-inflammatory effect of air pollution was observed, which indicates that air pollution does not facilitate allergen-induced inflammatory responses.

Exhaled NO level and number of eosinophils in nasal lavage as markers of pollen-induced upper and lower airway inflammation in children sensitive to grass pollen.

OBJECTIVES: This study investigates the upper and lower inflammatory response induced by natural exposure to grass pollen in atopic and non-atopic children. METHODS: After children's atopic profile had been assessed, their nasal lavage fluid (NAL) and exhaled air was sampled once before and once during the pollen season. Level of nitric oxide (NO) was determined in exhaled air, and the following mediators were measured in NAL: ECP, IL-6, IL-8, albumin, uric acid, and urea. The number of eosinophils in NAL was determined after Giemsa staining. During the experiment ozone and pollen levels were measured continuously. RESULTS: During the pollen season the level of grass pollen was 95 pollen grains per cubic metre. At baseline, 8.0% and 5.4% of total cells in NAL of children sensitive to, respectively, house dust mite (HDM) and pollen + HDM were eosinophils, whereas virtually no eosinophils were observed in NAL of non-atopic children. In contrast to the non-atopic and HDM groups, in children sensitive only to grass pollen, grass pollen induced a threefold increase in the percentage of NAL eosinophils and a 2.5-fold increase in the NAL level of ECP ( P<0.05). In all groups, the NAL levels of albumin, uric acid, urea, IL-6 and IL-8 were not significantly increased by pollen exposure. At baseline, children sensitive to HDM showed significantly higher exhaled nitric oxide (eNO) values than non-atopic subjects and children sensitive only to pollen (79 to 141% increase). During pollen exposure eNO of children sensitive only to pollen increased from 35.8 to 64.5 ppb ( P<0.05), whereas no increase in eNO was observed in the other children. CONCLUSION: Pollen-sensitive children show a season-dependent upper and lower airway inflammatory response, resembling the continuous inflammation in HDM-sensitive children.

Relation between airborne pollen concentrations and daily cardiovascular and respiratory-disease mortality.

In a time-series study in The Netherlands, we found a strong association between the day-to-day variation in pollen concentrations and that of deaths due to cardiovascular disease, chronic obstructive pulmonary disease, and pneumonia.

Similarity in seasonal appearance between atmospheric birch-pollen grains and allergen in paucimicronic, size-fractionated ambient aerosol.

BACKGROUND: Specific allergen from various pollen types has been found to be carried through the outdoor air, not only by intact pollen grains, but also by much smaller, paucimicronic particles. There is no complete agreement on whether, for birch (Betula), the seasonal appearance of atmospheric pollen allergen follows the fluctuation pattern of the pollen season. METHODS: Assessment of birch-pollen allergen in size-fractionated ambient aerosol was performed by descending elution of allergen from impaction strips of a five-stage cascade impactor, and compared with atmospheric birch-pollen concentrations as measured with a volumetric pollen trap. RESULTS: An overall similarity in the courses of the seasonal presence was found for both birch pollen and allergen in particles of all paucimicronic size fractions, although some airborne allergen was detected before and after the birch-pollen season. CONCLUSIONS: Transfer of pollen allergen to both natural and pollutant environmental dust particles is thought to be the probable explanation of secondary allergen carriage by paucimicronic particles. Until simple techniques for direct and rapid assessment of atmospheric pollen allergen become available, the pollen count gives sufficiently reliable information about the seasonal course of airborne pollen allergen.

Pollen-related allergy in Europe.

The increasing mobility of Europeans for business and leisure has led to a need for reliable information about exposure to seasonal airborne allergens during travel abroad. Over the last 10 years or so, aeropalynologic and allergologic studies have progressed to meet this need, and extensive international networks now provide regular pollen and hay-fever forecasts. Europe is a geographically complex continent with a widely diverse climate and a wide spectrum of vegetation. Consequently, pollen calendars differ from one area to another; however, on the whole, pollination starts in spring and ends in autumn. Grass pollen is by far the most frequent cause of pollinosis in Europe. In northern Europe, pollen from species of the family Betulaceae is a major cause of the disorder. In contrast, the mild winters and dry summers of Mediterranean areas favor the production of pollen types that are rarely found in central and northern areas of the continent (e.g., the genera Parietaria, Olea, and Cupressus). Clinical and aerobiologic studies show that the pollen map of Europe is changing also as a result of cultural factors (e.g., importation of plants for urban parklands) and greater international travel (e.g., the expansion of the ragweed genus Ambrosia in France, northern Italy, Austria, and Hungary). Studies on allergen-carrying paucimicronic or submicronic airborne particles, which penetrate deep into the lung, are having a relevant impact on our understanding of pollinosis and its distribution throughout Europe.

Effects of photochemical air pollution and allergen exposure on upper respiratory tract inflammation in asthmatics.

Asthma is an inflammatory disease of the airways, and exacerbations of this disease have been associated with high levels of air pollution. The objective of this study was to examine whether ambient air pollution and/or allergen exposure induces inflammatory changes in the upper airways of asthmatics. Sixty patients with intermittent to severe persistent asthma visited the Hospital's Out Patient Clinic every 2 wk for a period of 3 mo, and on each visit a nasal lavage was obtained. Associations between nasal inflammatory parameters and seasonal allergens and/or air pollution exposures were analyzed using linear regression analysis. The study ran from July 3 to October 6, 1995, during which period ozone (8-h mean: 80 micrograms/m3) and PM10 (24-h mean: 40 micrograms/m3) were the major air pollutants; the major aeroallergen was mugwort pollen (24-h mean: 27 pollen grains/m3). Effects on both cellular and soluble markers in nasal lavage were demonstrated for both ozone and mugwort pollen, but not for PM10. Ambient ozone exposure was associated with an increase in neutrophils (112% per 100 micrograms/m3 increase in 8-h average ozone concentration), eosinophils (176%), epithelial cells (55%), IL-8 (22%), and eosinophil cationic protein (ECP) (19%). Increases in environmental mugwort pollen counts were associated with an increase in nasal eosinophils (107% per 100 pollen/m3) and ECP (23%), but not with neutrophils, epithelial cells, or lL-8. This study demonstrated that both ambient ozone and allergen exposure are associated with inflammatory responses in the upper airways of subjects with asthma, although the type of inflammation is qualitatively different.

Seasonal appearance of grass pollen allergen in natural, pauci-micronic aerosol of various size fractions. Relationship with airborne grass pollen concentration.

In a study during the 1993 grass pollen season at Leiden, the relationship between atmospheric pollen allergen carried by five size fractions of pauci-micronic (few microns) particles and the grass pollen count was investigated. Sampling was carried out on dry days, and atmospheric pollen allergen in the particle fractions was assessed by a RAST-inhibition assay while grass pollen quantities were measured with a volumetric pollen trap. It appears that the atmospheric presence of grass pollen allergen in all size fractions is restricted mainly to the period of presence of grass pollen grains. Before and after the grass pollen season atmospheric grass pollen allergen quantities are generally very low. It is concluded that a routinely performed grass pollen count is a reliable measurement for the estimation of the amount of atmospheric grass pollen allergen, also in the pauci-micronic particle fraction.

Temperature influence on differentiation and release of hazel pollen.

The aim of the present work was to identify the classic phenological stages, and to understand its relation to catkin differentiation and growth, and its consequences for the start of pollination. Phenological observations and an aeropalynological survey on Corylus avellana, which is an example of an economically and allergologically interesting arboreal plant, were carried out during 1991-1992. The comparison between the different phenological phases and the aeropalynological data, showed that the pollen trap recorded hazel-pollen presence in the atmosphere immediately after the pollen release from the orchard. The start of catkin elongation in late winter, after the chilling requirement has been fulfilled, could be used to indicate the beginning of heat accumulation necessary for pollination.

Evidence of grass-pollen allergenic activity in the smaller micronic atmospheric aerosol fraction.

In June 1988, during the grass-pollen season in Leiden, The Netherlands, outdoor airborne particulate matter was collected and separated into fractions according to aerodynamic sizes (greater than or equal to 10 microns, 4.9-10 microns, 2.7-4.9 microns, 1.3-2.7 microns, 0.6-1.3 microns, less than or equal to 0.6 microns), with a cascade impactor mounted on top of a high volume sampler. The different fractions were tested for the presence of grass-pollen allergenic activity using a RAST-inhibition assay: specific IgE-antibody-containing patient serum was applied on the particle-loaded impaction strips, and the serum was recovered by descending elution for further analysis in the RAST. Simultaneously, continuous measurements were made of the airborne grass-pollen concentration using a volumetric pollen trap. Sampling observations lasting 7-9 hr during a period with relatively high airborne grass-pollen concentrations showed reliably detectable amounts of grass-pollen allergen, not only in the first impaction stage where intact pollen were collected, but also in the lower stages collecting the smaller, paucimicronic and submicron atmospheric aerosol fraction. It is evident that this result has serious implications for the understanding of the bronchial symptoms frequently seen in hay fever patients on days with high pollen concentrations in the air.

City spore concentrations in the European Economic Community (EEC). VII. Oleaceae (Fraxinus, Ligustrum, Olea).

In this paper we present the results of volumetric sampling of the airborne pollen grains of the Oleaceae family (Fraxinus, Ligustrum and Olea) in some European towns, in the period from 1982 to 1986. The sampling and appraisal of pollen content in the air is of particular interest to clinicians and allergic patients in order to assess exposure to the various pollen types in relation to allergy. In the Oleaceae family, the most allergenic pollen is produced by Olea europaea, the olive tree, which in the Mediterranean area has a pollination period lasting from May to the end of June and sometimes causes severe symptoms of pollinosis. In Northern and Central Europe, where there are no olive trees, there are two other commonly occurring genera of the Oleaceae family, namely Fraxinus and Ligustrum, but these have a low frequency of allergic sensitization.

Birch pollen asthma in The Netherlands.

The occurrence of birch pollen asthma is related to high birch pollen concentrations in the air, and therefore this type of asthma is rather common in Scandinavia. High birch pollen concentrations are rare in The Netherlands, but in the spring of 1984 extremely high levels were reached, whereas the concentrations of alder and hazel pollen were very low. During this period nine pollinosis patients known to the allergist developed asthmatic complaints. The appearance and disappearance of the asthmatic symptoms in these patients showed strong correlation with the course of the birch pollen concentration in the air, which strongly suggests that birch pollen asthma can occur in The Netherlands. The significance of this finding may be that this type of asthma can be observed regularly when the birch pollen concentrations are very high. This may also hold for other western European countries.

Daily hay fever forecast in the Netherlands. Radio broadcasting of the expected influence of the weather or subjective complaints of hay fever sufferers.

The literature on local pollen counts and their significance for hay fever is reviewed and a system for forecasting hay fever is described. Such forecasts have been broadcast by radio in The Netherlands since 1977. The hay fever forecast takes the form of a prognosis (in terms of three grades) of the influence of the expected whether situation on tomorrow's course of the subjective complaints of hay fever sufferers. It is not a forecast of the pollen count. When the subjective complaints of about 150 hay fever patients were used as reference for evaluation, the forecasts proved to have been correct in 72, 85, and 88% of the cases in 1977, 1978, and 1979, respectively. The practical usefulness and the limitations of the system are briefly discussed, with emphasis on the principle that not the local pollen count but the weather should be taken as the main determinative factor for the expected subjective experiences in a group of hay fever sufferers in a certain region.

City spore concentrations in the European Economic Community (EEC). IV. Summer weed pollen (Rumex, Plantago, Chenopodiaceae, Artemisia), 1976 and 1977.

This paper describes observations on the airborne pollen concentrations of four anemophilous weeds of very common occurrence in Western Europe, viz. Rumex spp .(sorrel and dock), Plantago spp. (plantain), Chenopodiaceae (goosefoot family) and Artemisia spp. (mugwort). Comparative results are recorded from London, Leiden, Brussels, Munich and Marseilles for the summers of 1976 and 1977 and this study is one of a series involving international collaboration between workers in cities of the European Economic Community. The literature on the clinical significance of summer weed pollen is reviewed and it is concluded that the pollen of Artemisia is likely to be of importance in areas where the weed is of common occurrence in late summer. The pollen of the other summer weeds is unlikely to be important, but may contribute to the problems of the pollen sensitive patient under exceptional circumstances.