Phosgene breaks down in the environment on timescales measured from hours to days. The five-day evac window was more than enough to remove all appreciable amounts of phosgene from the environment. And given how reactive it is, you can trust the lack of anyone showing up in a hospital in east Ohio looking like they climbed out of an eastern-front trench as indicative that the phosgene has not caused harm.

It's real easy to over-estimate the damage this spill will do. In practice, people have been using (and spilling) vinyl chloride for over 180 years; we have a pretty good sense of the damage it can do. Not a good situation, but far on the low end of environmental impact risks (somewhere north of "a car full of diapers" and far, far south of "a car full of perchloroethylene").