That's a line in Dorian Gray--- the movie and the novel. Is, or was, there an expression like that, or some superstition, or concern about the fog that way? I couldn't find out with a little googling. But it's a good line, isn't it? A poem should start with it.
How would your poem go, if it started with that line?
I'll write one if you will. We could all write one. Just off-the-cuff, even. Or not.