Airborne pollen transport

Abstract

This chapter reviews the present knowledge and previous developments concerning the pollen transport in the atmosphere. Numerous studies are classified according to the spatial scales of the applications, key processes considered, and the methodology involved. Space-wise, local, regional and long-range scales are distinguished. An attempt of systematization is made towards the key processes responsible for the observed patterns: initial dispersion of pollen grains in the nearest vicinity of the sources at micro-scale, transport with the wind, mixing inside the atmospheric boundary layer and dry and wet removal at the regional scale, and the long-range dispersion with synoptic-scale wind, exchange between the boundary layer and free troposphere, roles of dry and wet removal, interactions with chemicals and solar radiation at the large scales. Atmospheric dispersion modelling can pursue two goals: estimation of concentrations from known source (forward problem), and the source apportionment (inverse problem). Historically, the inverse applications were made first, mainly using the simple trajectory models. The sophisticated integrated systems capable of simulating all main processes of pollen lifecycle have been emerging only during last decade using experience of the atmospheric chemical composition modelling. Several studies suggest the allergen existence in the atmosphere separately from the pollen grains - as observed in different parts of the world. However, there is no general understanding of the underlying processes, and the phenomenon itself is still debated. Another new area with strongly insufficient knowledge is the interactions of airborne allergens and chemical pollutants.