Smoke, by Dan VyletaRead about another entry on the list.
Vyleta’s Victorian England setting looks deceptively like the one that actually existed, with one very big difference: impure thoughts and evil doings cause you to leak black “smoke” as a visual symbol of sin. As a result, the upper classes maintain power by demonstrating a lack of smoke, thus establishing their moral superiority over everyone else. There’s a mystery to the phenomenon, which is relatively recent, and half the fun is tracing how smoke has altered life in this alt-London.
--Marshal Zeringue