When you see the nuclear symbol, you know you are walking in a radiation area (like chernobyl). We need those, so we are aware of where we are, in which reality we are, so we can respond, and so that it will make sense to follow those strict guidelines, like keeping 6 feet away (since it takes a lot of time for people to start responding to that, they only start when people are already dying). That's what I did here, I gave a very clear indication of what people should do when they are outside their houses, since social isolation is the second most important rule after quarantine. Used the bio safety symbol: akin to the nuclear symbol, although I am using it very small(we don't need panic, just information). -Color orange - it is very much used on public signage when things are at a pause, like stopping at traffic, waiting, or ambulance in many cities, etc.