Emergency mylar blankets can be a useful tool for keeping warm under the right conditions, but they do have their limitations. Under certain circumstances they may not be as effective as expected and when used under the wrong conditions, the result can be death. Their primary purpose is to keep you warm under limited conditions, not get you warm.
How They Work
It is important to understand that these emergency blankets work by reflecting a portion of your body heat. Therefore, you must have sufficient body heat to begin with for them to be effective. The colder you become before using the blanket, the less effective it will be. They are not as effective in long-term use or when in severe weather. They are completely ineffective in the case of hypothermia. In the case of hypothermia, external sources of heat are required for survival. Again, they will keep you warm under limited conditions, but not get you warm.
Things to Keep In Mind
With this in mind, it is prudent to use the blanket early in an emergency situation before body heat is lost. Most of your body heat is lost through your head, so keep your head covered with a good hat or alternative covering. Also, you can create body heat by exercising before covering yourself with the blanket. You will need to use prudence here, however, as moisture created from sweat and physical exhaustion are contributing factors to hypothermia. Dry clothing is also essential for maintaining body warmth. Do all that you can to keep dry or to change into dry clothes. Keep yourself hydrated. Try out the blanket in various conditions and for various lengths of time before needing one in an emergency.
Other Ideas for Keeping Warm
Be prepared to engage an alternative plan for creating heat and/or insulating. Other things that you may want to include in your 72-hour kit are waterproof matches, a can of Sterno, a change of clothes, a hat, mittens, and hand/body warmers. Keep warm blankets in your car for additional insulation. Should you get stranded in your car, you can use the foam in your seats to insulate your body by stuffing it inside your clothing.
Besides keeping you warm under the right and limited conditions, your emergency blanket can provide some limited protection from the elements, be useful as a ground cover, as a reflector to signal for help, to collect water or for reflecting the sun away from you or toward something you want heated. Emergency mylar blankets can be a useful tool…just remember that any tool is only useful when used correctly and safely.
Click here for a printable PDF file of these warnings to insert into your 72 Hour Kits.