I think I should start with that the story you're trying to tell really isn't suited for the Item format. The actual anomaly seems of very little interest to you, and you focus mostly on an insu op that just happens to use this Item for world domination. Without further details on how that thing works (reminder, we're predominantly a horror site, you can go wild with the side-effects and squick!) and where it came from, I suggest you write a tale instead.
Second, you treat this thing as far more powerful than it really is — even the SCP wiki generally agrees that the Foundation has plenty of airborne agents including strong hallucinogens and amnestics. Sure, you "changed the atmosphere", but do you really think they haven't dealt with worse? Especially since your John Doe schmuck from off the streets who suddenly gained awareness of the Foundation isn't going to do much. Even if he somehow knows of all their locations (which even we don't) and defences, it's just your average Joe without any expertise in breaching fortified installations or handling anomalies. These people are essentially smarter, but frail zombies, unless we somehow managed to provide gear and training for each of them.
Narratively, this win feels completely undeserved and more like somebody's power fantasy. The Insurgency can resort to powerful weapons, yes, but they usually have a cost, a drawback, or at least a story, instead of being mere diabolos ex machinae for easy wins. Your story condenses down to "Insurgency uses magic anti-foundation gas. Insurgency wins." which isn't a particularly compelling plot which on top of that runs into the problem of clashing with every other article on here (even baron's A Possible World!) and when faced with accepting either everything else they like, or your incumbent story, I'm afraid you fall victim to Zawinski's other law: "Don't remind the audience of a better movie they could be watching instead."
Normally I give tips on salvaging drafts, but frankly I don't even know what you were trying to do here, so all I can give is generic pointers.
