The exceptional ability of alpha-tocopherol (alpha-TOH) for scavenging free radicals is believed to also underlie its protective functions in respiratory epithelia. Phenols, however, can scavenge other reactive species. Herein, we report that alpha-TOH/alpha-TO- reacts with closed-shell O-3(g) on the surface of inert solvent microdroplets in <1 ms to produce persistent alpha-TO-O-n(-)(n = 1-4) adducts detectable by online thermospray ionization mass spectrometry. The prototype phenolate PhO-, in contrast, undergoes electron transfer under identical conditions. These reactions are deemed to occur at the gas/liquid interface because their rates: (1) depend on pH, (2) are several orders of magnitude faster than within microdroplets saturated with O-3(g). They also fail to incorporate solvent into the products: the same alpha-TO-O-n(-) species are formed on acetonitrile or nucleophilic methanol microdroplets. alpha-TO-O-n = 1-3(-) signals initially evolve with [O-3(g)] as expected from first-generation species, but alpha-TO-O- reacts further with O-3(g) and undergoes collisionally induced dissociation into a C19H40 fragment (vs C19H38 from alpha-TO-) carrying the phytyl side chain, whereas the higher alpha-TO-O-n >= 2(-) homologues are unreactive toward O-3(g) and split CO2 instead. On this basis, alpha-TO-O- is assigned to a chroman-6-ol (4a, 8a)-ene oxide, alpha-TO-O-2(-) to an endoperoxide, and alpha-TO-O-3(-) to a secondary ozonide. The atmospheric degradation of the substituted phenols detected in combustion emissions is therefore expected to produce related oxidants on the aerosol particles present in the air we breathe.