Im gonna go out on a lim....... window cleaners working safely will not contribute to the spread of covid-19.
Someone has already beaten you to that little gem. And he claims The Chief Medical Officer backs him up.
Perhaps you could make up a slogan.
I had a window cleaning mate with a similar attitude. Addicted to sugar. Always eating Bounty bars, chocolate raisins and marshmallows. I warned him about diabetes but he said he was immune and that it wouldn't spread in the window cleaning fraternity. But he did catch diabetes and had to have a leg amputated. I picked him up from the hostipal and got him a wheelchair but he wouldn't have it. Pig headed, as ever, he even refused crutches and said he'd get to the car by himself.
He went out on a limb.
Stay safe.