Emergency blanket: how to use one
An emergency blanket (space, foil or mylar blanket) is a thin sheet of aluminized plastic film that reflects body heat back and keeps wind off. Wrap it close around the person, silver side toward the body, with something thick and dry between them and the ground. It holds in heat the body makes and produces none. If someone may have hypothermia, call 911.
What the blanket is made of
NASA developed the material to protect Apollo astronauts: "aluminized polymer film" that, in a space suit, "reflects the astronauts' body heat back to them for warmth." The same film, often sold as mylar, became the space blanket.
Germany's statutory accident insurers (DGUV) explain why it works in first aid: the silver side toward the body reflects body heat, and because the blanket is windproof it stops further cooling, especially outdoors.
Six ways to use it
Warmth is the main job. The others come free.
| Use | How | Source |
|---|---|---|
| Keep a cold person warm | Silver side to the body, wrapped close, head covered | DGUV, St John Ambulance |
| Wear it under your jacket | The Tyrolean wrap, step by step below | German Alpine Club (DAV) |
| Block the cold ground | Spread it under the person, on top of a thick dry layer | UC3M, St John Ambulance |
| Keep off rain and wind | Use it as a raincoat or windbreaker | UC3M |
| Be seen | The reflective surface marks where an injured person lies | UC3M |
| Shade in hot sun | Silver side out, with room for air to move underneath | UC3M |
UC3M is the prevention service of Carlos III University of Madrid. Which side faces in, from each source, is in the steps below.
How to wrap it
Two ways: around someone who is cold, or on yourself before you get cold.
01Around someone who is cold
- Get them out of the wind, indoors if you can.
- Swap wet clothes for dry ones if you have spares, and cover their head.
- Put a thick layer of dry material between them and the ground.
- Wrap the foil blanket around them, silver side in. Germany's DGUV says "Silberseite innen" (silver side inside).
- Call 911, stay with them and keep checking their breathing.
Source: St John Ambulance, DGUV
02On yourself, under a jacket (Tyrolean wrap)
- Lay the blanket flat against your back, over your base layer.
- Pull it up under your jacket from the bottom.
- Draw the top over your head like a headscarf and knot it under your chin.
- Bring the lower part around one side under the arm to the chest, and tuck the rest into your trousers.
- Put every other layer you have on top.
Source: DAV
What it won't do
Know these before you count on one.
- It makes no heat. It reflects what the body gives off. Wilderness Medical Society guidance says moderate and severe hypothermia need active warming, which is a job for emergency services.
- Laid loosely on top it does little. The German Alpine Club says plain draping "bringt wenig" (brings little); wrap it close, like the Tyrolean wrap.
- It is too thin to insulate from the ground on its own. St John Ambulance asks for a thick layer of dry material underneath.
- It doesn't stand in for a real blanket. Ready.gov's home kit still holds a sleeping bag or warm blanket for each person.
- It is first aid. Anyone who may have hypothermia needs emergency services as well.
How many to pack
One per person is the pattern across the lists.
| Kit | What the list says | Source |
|---|---|---|
| Go bag | "Lightweight raingear and Mylar blanket" in every household member's bag | NYC Emergency Management |
| Emergency backpack, Romania | Thermal foil in the minimum list per person, next to a blanket or sleeping bag | DSU |
| Day hike | An emergency shelter: a tent, space blanket, tarp or bivy | National Park Service |
| Mountain tour | At least 1 emergency blanket and 1 bivy sack per 2 people | DAV |
| Home kit | A sleeping bag or warm blanket for each person | Ready.gov |
| Car, winter | Blankets or sleeping bags | NWS |
For the trunk, see the car emergency kit. For a cold house, how to stay warm in a winter power outage.
Questions people ask
What is an emergency blanket made of?
A thin plastic film coated with aluminum. NASA calls the material "aluminized polymer film"; mylar is a common brand of that film.
Which side of a space blanket goes toward the body?
For warmth, the silver side faces the body, per Germany's DGUV and Madrid's UC3M. In hot sun, UC3M turns the silver side out for shade.
Do mylar blankets really keep you warm?
They cut heat loss by reflecting body heat and blocking wind, which works best wrapped close with dry insulation under the person. They don't produce heat.
How many emergency blankets should I pack?
One per person in each go bag, as NYC lists. Germany's Alpine Club asks for at least one per two people on a mountain tour, with a bivy sack.
Where should I keep one?
In every go bag, the car and the first aid kit. Germany's DGUV first aid handbook reaches for "the rescue blanket from the first aid kit", so that is where people look for it.
Read next
Sources
- NASA Spinoff 2004: Consumer Goods Radiant Barrier, aluminized polymer film, space blankets.
- DGUV Information 204-007: Handbuch zur Ersten Hilfe, Thermische Schädigungen (in German) Silver side to the body, windproof, no alcohol.
- St John Ambulance: Hypothermia Shelter, dry layer under, foil survival blanket, call for help.
- Deutscher Alpenverein: Unterkühlung und Erfrierung am Berg (in German, Feb 2026) Tyrolean wrap, 1 blanket and 1 bivy per 2 people.
- American Family Physician: Accidental Hypothermia, guidelines from the Wilderness Medical Society (2020) Insulation and a vapor barrier, active warming for moderate and severe cases.
- UC3M Prevention Service: Primeros auxilios (in Spanish) Which side out in cold and heat, other uses.
- NHS: Hypothermia
- CDC: Preventing frostbite and hypothermia
- NYC Emergency Management: Gather Supplies
- National Park Service: The Ten Essentials
- DSU and Bucharest Community Foundation: 72 de ore după cutremur (PDF, in Romanian)
- Ready.gov: Build a Kit
- National Weather Service: Before a winter storm