The Effect of Atmospheric Aging on the Toxicity of Bare and Coated Soot Particles

YINON RUDICH, Michal Pardo, Hendryk Czech, Svenja Offer, Sebastiano Di Bucchianico, Astrid Kiendler-Scharr, Ralf Zimmermann, AeroHealth Team , Weizmann Institute of Science

     Abstract Number: 89
     Working Group: Health-Related Aerosols

Abstract
Soot particles (SP) are ubiquitous components of atmospheric particulate matter. They are known to cause adverse health effects. In the atmosphere, freshly emitted SP can be coated by condensed low-volatility secondary organic and inorganic species. In addition, gas-phase oxidants may react with the surface of soot particles. We investigated the biological responses of lung epithelial cells following exposure to fresh- and photochemically aged-SP at the air–liquid interface. In addition, we studied how coating SP by biogenic and anthropogenic model SOA affects SP toxicity. A comprehensive physical and chemical aerosol characterization was performed to depict the atmospheric transformations of bare SP, showing that photochemical aging increased the organic carbon fraction and the oxidation state of the SP. We will present RNA-sequencing and qPCR analysis showing varying gene expression profiles for fresh-, aged- and coated SP. Exposure to aged- SP increased DNA damage, oxidative damage, and upregulation of NRF2-mediated oxidative stress response genes compared to fresh SP. Furthermore, aged-SP augmented inflammatory cytokine secretion and activated AhR-response, as evidenced by increased expression of AhR-responsive genes. These results indicate that oxidative stress, inflammation, and DNA damage play a vital role in the cytotoxicity of SP in lung epithelial cells, where aging leads to higher toxic responses. Our results suggest that photochemical aging increases SP toxicity through surface modifications that lead to an increased toxic response by activating different molecular pathways. Coating by SOA and atmospheric aging further increases SP toxicity. This work was partially funded by the Helmholtz International lab AeroHealth and the Weizmann Institute.