there with that population density. Almost everyone is in an apartment. If/when you go out to the grocery, you're touching doorknobs and doors that have been touched by everyone in the building. You have to be crazy vigilant on almost every surface outside of your home. Heck, even if someone sneezed in the foyer 10 minutes before you entered that area, you'd never know they sneezed and it could still be airborne.

As opposed to most of us suburbanites, or less dense city dwellers. On the occasions I've gone to the grocery store, I know my car hasn't had anyone else touch it, nor my house doorknobs, nor the garage switch. My exposure is while I'm in the store, and I can mitigate that fairly well.