Abstract
Exposure to elevated air pollution levels can aggravate pollen allergy symptoms. The aim of this study was to investigate the relationships between airborne birch (Betula) pollen, urban air pollutants NO2, O3 and PM10 and their effects on antihistamine demand in Gothenburg and Malmö, Sweden, 2006–2012. Further, the influence of large-scale weather pattern on pollen-/pollution-related risk, using Lamb weather types (LWTs), was analysed. Daily LWTs were obtained by comparing the atmospheric pressure over a 16-point grid system over southern Sweden (scale ~3000 km). They include two non-directional types, cyclonic (C) and anticyclonic (A) and eight directional types depending on the wind direction (N, NE, E…). Birch pollen levels were exceptionally high under LWTs E and SE in both cities. Furthermore, LWTs with dry and moderately calm meteorological character (A, NE, E, SE) were associated with strongly elevated air pollution (NO2 and PM10) in Gothenburg. For most weather situations in both cities, simultaneously high birch pollen together with high air pollution had larger over-the-counter (OTC) sales of antihistamines than situations with high birch pollen alone. LWTs NE, E, SE and S had the highest OTC sales in both cities. In Gothenburg, the city with a higher load of both birch pollen and air pollution, the higher OTC sales were especially obvious and indicate an increased effect on allergic symptoms from air pollution. Furthermore, Gothenburg LWTs A, NE, E and SE were associated with high pollen and air pollution levels and thus classified as high-risk weather types. In Malmö, corresponding high-risk LWTs were NE, E, SE and S. Furthermore, occurrence of high pollen and air pollutants as well as OTC sales correlated strongly with vapour pressure deficit and temperature in Gothenburg (much less so in Malmö). This provides evidence that the combination of meteorological properties associated with LWTs can explain high levels of birch pollen and air pollution. Our study shows that LWTs represent a useful tool for integrated daily air quality forecasting/warning.
Highlights
Pollen allergy affects up to 40% of the population in Northern Europe (d’Amato et al 2007)
We studied the effect of concurrent high birch pollen and high air pollution levels on OTC sales of antihistamines, as compared to the effect of high birch pollen alone
This study has shown that airborne birch pollen concentrations varied closely in relation to Lamb weather types (LWTs) in both cities
Summary
Pollen allergy affects up to 40% of the population in Northern Europe (d’Amato et al 2007). In a study, assessing the situation in west Sweden from 2012, 29% of the population aged 20–46 was sensitized to grass and 24% to birch allergens (Bjerg et al 2016). Air pollutants act as irritants and can induce airway inflammation and disruption of epithelial barrier homeostasis, which facilitates the access of allergens to effector cells of the allergic immune response (Traidl-Hoffman et al 2009). It is important to understand conditions for coincident high exposure to pollen and air pollution, and to what degree pollutants contribute to airway symptoms. Such information is useful in forecasting and early warning systems integrating air pollution and pollen
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