Elena Gottardini This email address is being protected from spambots. You need JavaScript enabled to view it.1, Fabiana Cristofolini1, Antonella Cristofori1, Mario Meier2, Juanita Rausch3, David Jaramillo Vogel3, Benjamin Michen4 

1 Fondazione Edmund Mach, Via E. Mach 1, 38010 S. Michele all'Adige (TN), Italy
2 FUB, Forschungsstelle für Umweltbeobachtung AG, Alte Jonastrasse 83, 8640 Rapperswil, Switzerland
3 Particle Vision GmbH, c/o Friup, Annexe 2, passage du Cardinal 11, 1700 Fribourg, Switzerland
4 passam ag, Laboratory for environmental analysis, Schellenstrasse 44, 8708 Männedorf, Switzerland

Received: January 13, 2021
Revised: March 26, 2021
Accepted: April 11, 2021

 Copyright The Author's institutions. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited. 

Download Citation: ||https://doi.org/10.4209/aaqr.210010  

Cite this article:

Gottardini, E., Cristofolini, F., Cristofori, A., Meier, M., Rausch, J., Vogel, D.J., Michen, B. (2021). Automated Microscopy Techniques on Passively Collected Samples Provide Reliable Quantitative Data on Airborne Pollen. Aerosol Air Qual. Res. https://doi.org/10.4209/aaqr.210010


  • Optical microscopy (OM) and SEM/EDX are applied on aerobiological passive samples.
  • Filtering criteria are used to automatically detect the total pollen fraction.
  • By OM, the 20–80 µm bright particle fraction represents well the pollen-candidates.
  • By SEM/EDX, morpho-chemical features allow to filter the pollen-like particles.
  • Passive sampling & automated analysis allow intensive air quality studies.


Data on airborne particles are of great importance for human health. Anthropogenic (e.g., soot, tire and brake wear) as well as biogenic (e.g., pollen, spores) particles are usually monitored by active samplers located in urban environments; thus, very few data are available for remote, mountainous areas. In addition, bioaerosol analysis is time-consuming and skill-demanding. This study was carried out to explore if passive sampling combined with automated analysis methods for pollen detection could be an option to overcome the constraints of active sampling (i.e., costs, electricity need) and to simplify data analysis. For this purpose, two Sigma-2 passive samplers were exposed during twelve one-week periods in 2018 in San Michele a/A (Italy), where airborne pollen has been monitored since 1990 by a volumetric Hirst-type sampler. Samples were analyzed by (i) automated optical microscopy (OM) followed by image analysis based on particle size and grey values, and (ii) automated scanning electron microscopy coupled to energy dispersive x-ray spectroscopy (SEM/EDX), delivering morpho-chemical information of single particles. By the automated OM, bright particles (i.e., from natural source) in the size range of 20-80 µm well represented the total pollen amount. By filtering the particles for size, shape and chemical composition, the SEM/EDX allowed to select the pollen-like fraction. In conclusion, automated analytical approaches can simultaneously provide data on anthropogenic, geogenic and biogenic airborne particles, including pollen. In addition, passive sampling is a reliable option for aerobiological studies, especially suitable in remote areas, where the maintenance of active samplers is challenging.

Keywords: Aerobiology, Sigma-2 sampler, Hirst-type sampler, Airborne particles, SEM/EDX

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