I know that the title can be subjective, what is and can be hazardous? I think something that can bite or sting is right up there. It could be a dog, snake or bug or someone who is driving recklessly. But in my day to day it’s the bugs that can be the most dangerous. Let’s say you’re cleaning the garage, you put your hand into a box handle and something bites you. That is bad news cause it could be a Black Widow spider. I personally would rather be stung by a scorpion than bitten by a Black or Brown Widow. So wear gloves (IPM) and always protect yourself when gardening or moving stuff. That storage shed that you haven’t been in for 1+ years might hold a few bugs or pests including honeybees.