Bioegenic aerosols : pollen

Theme headed by Alain Miffre 

    Pollen play a crucial role as indicators of the Earth's climate disruption, with periods of pollination becoming earlier, more frequent and more intense, with colossal impacts on human health and the health of the environment. As an example, 15.8 million people in Europe are clinically sensitised to ragweed pollen, with a colossal economic cost of around 7 billion euros (Schaffner et al., 2020).  

    Pollen are complex particles exhibiting an overall spherical shape with small-scale complex morphological features such as spikes, apertures and sub-micrometric cavities (Halbritter et al., 2018). As a result, no analytical solution to Maxwell's equations exists for pollen, which, due to their large size, are beyond the reach of numerical light scattering models. To face this complexity, a controlled-laboratory instrument, called LIAPS (for Laboratory Instrument for Aerosol Polarimetry and Spectroscopy) has been developed at iLM at exact lidar backscattering angle, the key direction for lidar remote sensing experiments (Miffre et al., 2020). This new instrument allows evaluating the backscattering lidar particles’ depolarization ratio of various pollen such as birch, ragweed, pine or cypress (Cholleton et al., 2022), hence opening new insights in lidar remote identification of pollen. 

Figure 1. Scanning electron microscopy (SEM) images of the studied pollen grains, respectively,
(a) ragweed, (b) ash, (c) birch, (d) pine obtained at the CTμ at Lyon University, as well as cypress and spruce.

Figure 2. Lidar PDR of pure pollen at 355 and 532 nm wavelengths measured for the first time in the laboratory at lidar exact backscattering angle of 180.0° (Remote Sensing, 2022).

Latest publications :

Laboratory evaluation of the (355, 532) nm particles depolarization ratio of pure pollen at 180.0° lidar backscattering angle, Remote Sensing, 14, 3767, (2022).

Laboratory evaluation of the scattering matrix of ragweed, ash, birch and pine pollens towards pollen classification, Atmos. Meas. Tech., 15, 1021-1032, (2022).  

Laboratory evaluation of the (VIS, IR) scattering matrix of complex-shaped ragweed pollen particles, JQSRT, 254, (2020).

Latest communications :

Invited talk : Les pollens : du laboratoire à l’atmosphère, Conférence PAMO, Société Française d’Optique, Session Lidar et Sciences du Vivant, Rouen, (2024).

Evaluation en labroratoire de la matrice de diffusion de pollens : applicabilité à leur classification, Congrès Français des Aérosols, ASFERA, (2022). 

Diffusion optique de bioaérosols résolue en polarisation : étude de cas sur le pollen d’ambroisie, Congrès Français des Aérosols, ASFERA, (2021).

Laboratory evaluation of the scattering matrix of pine, birch, ash and ragweed pollen, European Aerosol Conference, Manchester (on-line), Great Britain, (2021).