1.2 — The Rule of Threes, and Triage Thinking

A person can survive roughly:

Three minutes without air.

Three hours without shelter in a hostile temperature.

Three days without water.

Three weeks without food.

**The numbers are approximate and they vary enormously with the person and the conditions. What they are for is not precision. They are for ordering.

Why the ordering is the point

Because in almost every emergency, people work on the wrong thing.

The lost hiker looks for food. **They have three weeks. They have three hours if the temperature drops and they are wet.

The person in a flooded house saves possessions. They have minutes.

The person at a collapse pulls at rubble with their hands. Somebody nearby has an airway problem that will kill them in three minutes.

The rule of threes tells you, in ten seconds and without expertise, what has to be dealt with first.

And the general form is: work in the order of how fast it kills.

Air, in three minutes

Fastest, and it is what every medical protocol starts with.

What blocks it: an obstruction in the airway (3.4), an unconscious person's own tongue, cardiac arrest stopping circulation (3.2), smoke, water, or being unable to expand the chest.

What to do first, in any situation with an unresponsive person: check whether they are breathing. Ten seconds. Look at the chest, listen, feel.

And if not, that is the whole of your problem until it is fixed.

Blood, in minutes

Not in the traditional rule and it belongs here, because severe bleeding kills on a similar timescale.

A major arterial bleed can be fatal in minutes and is completely controllable by pressure (3.4).

The order that emergency services use is airway, breathing, circulation — and in trauma with obvious catastrophic bleeding, the bleeding is dealt with first, because it is faster.

Temperature, in three hours

The most underestimated item on the list, and the one that kills people who thought they were fine.

Hypothermia does not require snow. **It requires being wet and in wind at temperatures that feel mild — 10 to 15 degrees is entirely sufficient. Water conducts heat away roughly twenty-five times faster than air, which is why wet clothing is the single most dangerous condition in the wilderness chapters (7.2).

And heat kills faster than most people expect (5.10).

What to do: get dry, get out of wind, get insulation between you and the ground. The ground takes more heat than the air does, and people lying on cold ground lose heat far faster than they expect.

Water, in three days

Roughly three days without any, and functionally you are impaired long before that.

Dehydration degrades judgement early, which is what makes it dangerous in a situation requiring decisions.

And the practical note: do not ration water in a way that leaves you dehydrated while carrying full bottles. The advice from search-and-rescue is to drink when thirsty and spend the effort finding more, because a dehydrated person makes worse decisions about finding water.

Food, in three weeks

Last, and it is nearly always the thing people worry about first.

You will be unpleasant to be around and you will not be dead. In almost every short-term survival situation, food is irrelevant.

The triage version

And the same ordering, applied when there is more than one person.

Formal triage systems exist and are used by emergency services, and the amateur version that matters is short.

If several people are injured, help in this order:

People who are not breathing but have a chance — an unconscious person whose airway is blocked, a drowning victim, a cardiac arrest. These are the ones where seconds of your time buy the most.

People with catastrophic bleeding.

People who are seriously injured but breathing and conscious.

And people who are walking and talking. They can wait, and they can help.

And the counter-intuitive part, which is the whole of triage: the loudest person is usually not the most urgent. **A person screaming has an airway and is conscious. The silent one is the one to check.

The other kind of triage

And this belongs here because Part 2 uses it constantly.

The same ordering applies to a non-physical crisis, and the question is the same: what fails fastest?

In a job loss (2.3): not the career plan. The runway. **How many months of essential spending you have, and what the order of cuts is. The career question can wait a fortnight; the money question determines how long you have to answer it.

In a medical crisis in the family (4.1): not the long-term prognosis. This week's practicalities — who is doing what, what has to be arranged, and who is sleeping.

And the general form: identify the thing that has the shortest fuse, deal with that, and refuse to be pulled into the larger and more distressing question until it is done.

This is not avoidance. It is sequencing, and it is the difference between a crisis you are managing and one that is managing you.

The one-minute assessment

Which is what the rule of threes actually gives you, and it is worth memorising as a sequence.

Am I safe where I am standing? **First, always. Rescuers who become casualties help nobody, and this is the most common single error in bystander incidents — approaching an electrical hazard, entering smoke, going into water.

Is anybody not breathing?

Is anybody bleeding badly?

Is anybody getting cold or too hot?

Do we have water?

What is the next single action?

Six questions, about a minute, and they correctly order almost anything.

What to do with this page

Memorise the four numbers. Three minutes, three hours, three days, three weeks.

Remember that the silent person is the urgent one.

Check your own safety before you approach anything. Every time. It is the most broken rule in this volume.

And apply the shortest-fuse question to non-physical crises too. What fails fastest, deal with that, and let the larger question wait a week.

Next: 1.3 — a protocol for the first sixty seconds that works for essentially any emergency.