Air

We don't usually think, or have to think, about access to breathable air, because air is all around us, and it's free. We never imagine that access to breathable air could be compromised, but the Corona Virus pandemic has got us thinking that, maybe, it can.

In a survival situation, the "Rule of Threes" prioritizes what the body needs in order to survive. Normally, the rule states that we can survive

3 minutes without breathable air, and
3 days without water, and
3 weeks without food.
Some people even add shelter to the list: 3 hours (in a harsh environment) without shelter.
Although it is a generalization, it is still very useful in determining priorities in an emergency situation.

One of the ways of ensuring that you have access to breathable air is by using a mask, or a respirator. A respirator is a mask that creates a facial seal causing the air to be filtered entering and exiting the wearer. The wearer must decide the type of respirator, or mask, based on the situation.