It's called hypoxemia, it's low levels of oxygen in the blood, to be more specific, it's oxygen loss in your blood from your arteries. It can cause respiratory disorders, and tissue hypoxia, as a result of the blood not providing much oxygen to your body.
I hope I helped :)
A carbon atom can form a maximum of 4 single covalent bonds
Because skin falls off, or are you talking bout why don't people stick together?
Jobs. Like a snow blowing company. They would not have that in Puerto Rico. But Canada might. Because they have a different enviornment.