The libertarian argument here would be "burning leaded gas is a tort against everyone else breathing the air", right? You clearly have to special case it becau

The libertarian argument here would be "burning leaded gas is a tort against everyone else breathing the air", right? You clearly have to special case it because the harm is so diffuse; you could presumably either have a government ban it, or have some objective standard where non-compliance is itself taken as a tort, and then something like class-action. There's the California option -- Prop 65 has this weird way for private people to find violations and be paid for them, although the enforcement action is taken by the state. I can't see "someone with a $0.0001 harm files suit against the aggressor" x 7b being a scalable solution without some kind of optimization. Maybe you could imagine some kind of little automated lawyer-agent which sues behind on your behalf, with everything happening at a micro-transaction level, but that seems kind of silly.