Latest death for me was acid rain.
I was being chased by zombie dogs and I hole up in a miscellaneous evac shelter because it had started drizzling acid.
First I had to fight off the zombie dogs, they break a window, attracting nearby wildlife. 2 cougars show up, then some giant spiders, then a pack of wolves, no big deal.
A zombie hulk sneaks up sideways from the window and promptly rips my arm off while shredding my rain coat, I back off a step and throw a molotov in front of him and run, the hulk burns to death trying to chase me over a row of benches.
I barely escape the burning ruin of the evac shelter and run towards the nearest building, my heavily damaged rain coat breaks almost immediately, then I disintegrate in the acid rain about halfway to my destination.
Lesson learned: Take off your rain coat when you get inside.