the Bunker Hill smelter just vented the sulfur dioxide out into the atmosphere, resulting in massive environmental damage in the Silver Valley. My neighbor relates his arrival in Idaho in 1970 ...

Instead, it's the opposite: Significant amounts of sulfur dioxide in a planet's atmosphere is a good sign that the world is uninhabitable and we can safely cross it off the list of candidates.

significant concentrations of sulfur dioxide in a planet's atmosphere can suggest that the planet is likely uninhabitable, allowing researchers to eliminate it from further consideration.