Funny, but yours is the first sci-fi anything I read that plays with dark matter. It's nice that you're keeping it almost entirely in the background, though, with no one in the story having any idea about how the tech works.
It does seriously amuse me to read about dark, black, malicious mist as a bi-product, when dark matter doesn't interact with EM radiation at all so our eyes or sense of temperature would be utterly useless.