We have 4,052 square miles in a county of 180,000 people. There’s more cows and manure spreaders but there’s still runs on Clorox and toilet paper. That’s about 400 square yards per person but most of it is wilderness. Northwesterly winds off the coast keep the air clean.
Of course Ferndale is where the (non-)fiction movie Outbreak was filmed so it’s already happened here, except a monkey and not a bat..a big ugly Chinese bat...be scared, be very scared.
Where did you get 4052 square miles for the US? The actual area is 3.8 Million square miles