Explainer Zone on Instagram: "In some large stadiums, flame cleaning (also called flame treatment) is used to quickly sanitize and refresh plastic seats. A controlled propane or natural gas flame is passed over the seat surfaces, which burns away dirt, dust, chewing gum, paint marks, and surface bacteria without damaging the plastic. The process works because the flame briefly heats the surface, loosening or vaporizing unwanted residues, while workers move the flame rapidly to avoid overheating.