A caveat to the implications above is that the particles used in our work were 60 to 120 µm in diameter, which is at least several times larger than atmospheric particles (approximately 10 nm to 10 µm in diameter). Finite size effects can suppress liquid-liquid phase separation when the diameter is ≲ 40 nm. In addition, finite size effects may sharply decrease viscosities of organic aerosols when the diameter is ≲ 100 nm. 138 Thus, we anticipate that our results apply to particles larger than approximately 100 nm, which covers most of the mass of BBOA in the atmosphere, but experiments are needed to verify this hypothesis.