A preprint submitted to arXiv on May 4, 2026, deploys Nano-CT to map the 3D microstructure of soot released during lithium-ion thermal runaway, revealing core-shell particles whose thin outer layers contain carcinogenic phases that conventional XRD mass-fraction measurements miss. The study uses laboratory-scale battery abuse tests whose exact cell count and capacity remain unspecified, limiting statistical power yet still demonstrating that even trace surface-bound toxins can become respirable hazards. Traditional two-dimensional imaging or bulk chemistry overlooks these geometries; Nano-CT instead shows how the shells adhere to carbonaceous cores, dramatically increasing inhalation risk during garage or tunnel fires. This work arrives amid surging EV adoption and documented incidents such as the 2023 Hyundai Kona and 2024 Rivian battery fires, where first responders lacked particulate-specific respiratory protocols. Complementary findings from the 2022 Nature Energy review on thermal-runaway emissions and a 2024 Environmental Science & Technology study of urban EV-fire aerosols indicate that current NIOSH and EPA guidelines underestimate ultrafine metal-oxide fractions. Regulators must now incorporate tomographic particle profiling into certification tests rather than relying solely on total-mass thresholds. Limitations include the preprint status, absence of in-vivo toxicology data, and focus on a single chemistry, underscoring the need for multi-lab validation before policy adoption.