Characterization of Particulate Matter Emissions from Fuels Used in Beekeeping Smoking Practices

Biomass combustion is a major source of particulate matter (PM) [1]. While emissions from residential and industrial biomass burning have been widely studied, limited attention has been given to smoking applications used in beekeeping, where smoke is routinely generated to calm bees during hive management. These emissions may represent a relevant but underexplored source of exposure for beekeepers. The aim of this study is to compare particulate emissions from different fuels commonly used in beekeeping smokers and to assess their emission characteristics and potential health implications. Representative fuels, including wood pellets, compressed fuels, jute, paper, and cardboard, were investigated under controlled laboratory conditions. The elemental composition of both raw materials and emitted particulate matter was determined by inductively coupled plasma mass spectrometry (ICP-MS) following collection using electric smoker and personal air-sampling pumps equipped with mixed cellulose ester (MCE) filters. Real-time particulate matter monitoring and high-resolution field emission scanning electron microscopy (HR-FESEM) were used to characterize PM fractions (PM₁, PM₂.₅, PM₁₀) and particle morphology. Marked differences in particulate emissions were observed across fuel types. Pellet fuels showed higher PM₁/PM₂.₅ ratios, indicating a predominance of fine particles, whereas processed cellulosic materials exhibited broader size distributions, highlighting the influence of fuel structure on particle formation mechanisms. Elemental analysis revealed the presence of several potentially toxic elements in both fuels and emitted particulate matter, including Cd, Cr, Cs, Cu, Mn, Pb, and Zn. Significant variability in elemental concentrations was observed across fuel types, indicating fuel composition as a key driver of exposure risk. In occupational context, repeated inhalation of contaminated smoke may pose health risks, particularly due to elements such as Cd and Pb, which are associated with chronic toxicity. The environmental dispersion of these emissions also raises concerns regarding pollinator health and the potential transfer of contaminants to honey and other hive products. Acknowledgements: This research was partially funded by Sapienza University of Rome, project 2025, grant number AR125199C0876C2A, and project 2023, grant number RM123188F73F6255.