<p>Organic films containing unsaturated lipids are widespread, yet their oxidation pathways with associated impacts on contaminant lifetimes and human exposure remain poorly explored under indoor environmental conditions. This study demonstrates that UVA radiation and radical exposure drive rapid autoxidation of thin films of methyl linolenate (ML) and canola oil (which contains polyunsaturated triglycerides), primarily producing organic hydroperoxides. For ML films this fast chemistry occurs at the same rate under entirely dark, genuine indoor conditions as it does when the films are exposed to significantly higher ^•OH radicals in a flow reactor. Both ^•OH and organic radicals are detected within the oxidized films, propagating fast autoxidation in dark indoor environments with minimal sensitivity to the radical initiation rate. When mixed into the films, bisphenol A is hydroxylated, illustrating potential transformation pathways for toxic organic contaminants. This study uncovers insights into lipid autoxidation processes under environmental conditions and underscores their potential health impacts.</p>