It may be shocking to learn that a gas with the odor of rotten eggs is actually not good for you, but sure enough: the U.S. EPA is considering regulating hydrogen sulfide, a nasty-smelling gas that emanates from oil refineries, paper mills, landfills, CAFOs, and any other place where organic material containing sulfur decomposes. Hydrogen sulfide is known to be deadly in high concentrations, but recent research indicates it may also lead to health problems at low levels of exposure. If the EPA decides to list hydrogen sulfide as an air pollutant, companies would have to increase data reports and potentially step up efforts to not release it. “I think that there are some significant quality-of-life issues that might be in hand here,” says a toxicologist with the American Petroleum Institute. But “we don’t believe that [listing hydrogen sulfide] will provide any additional value to the EPA … other than affirming what we already know.” In other words: We know it’s hurting people — now leave us alone.