Most people know they need to bundle up before venturing into the arctic conditions gripping Kansas these days.
But most people don’t do it properly.
They throw on extra sweatshirts and jackets to keep the torso warm and ignore the rest of the body, said an expert on cold-weather garb.
“You want to cover as much as the body surface as possible, and you want to evenly distribute the insulation over the body surface,” said Elizabeth McCullough, a professor of textiles and co-director the Institute for Environmental Research at Kansas State University.
McCullough conducts tests to determine temperature ratings of cold-weather clothing for manufacturers like L.L. Bean and the North Face.
She recommends using thick clothing materials like down and polyester fiber with a low-bulk density that trap still air, using several layers of garments, and covering the head, legs, hands and feet as well as the torso.
“You have to think of body as a system,” she said.
Layering helps trap body heat. When you layer garments, you trap a layer of air between each garment, and that air is what is doing the insulating, McCullough said.
Layering also allows for flexibility. You can remove a layer if you get too hot, she said. You may need a lot of insulation when you first step outside on a bitter day, but the temperatures and your levels of activity can change during the day.
“Your body should be in thermal balance,” McCullough said. “The amount of heat the body is producing should be equal to amount of heat that you are losing to the environment.”
Thickness of clothing is the most important variable, she said. That includes footwear.
While most people – no matter how well bundled – head into the cold weather in street shoes or sneakers, she recommends fiber-filled thick boots that cover the foot and the calf. They may not look fashionable, but you can change them when you get to the office, she said.
For the hands, mittens are warmer than gloves. In mittens, fingers keep each other warm, she said.
Also, she said, there is a smaller surface area for heat loss in a mitten.
“If a fabric is wrapped around each finger, you will lose heat faster than if they were all together inside the mitten,” McCullough said.
People may not be outside for long in this weather, McCullough said, “but if you’re stranded, you better have this stuff.”
And you’d better have a hat.
The head usually is the last thing that people cover in cold weather. That’s because the head doesn’t get as cold as quickly as the hands and feet.
When your body begins to feel cold, the surface blood vessels in the hands and feet constrict because they are carrying warm blood to your extremities, McCullough said. It’s the body’s first line of defense against the cold.
“This doesn’t happen in the head,” she said. “Your brain has to continue to receive blood flow, so your head surface stays warm while your hands and feet get cold.”
Which means you will lose heat from your head at a faster rate than from your extremities if you don’t cover it.
“Putting clothing all over your body and leaving the head sticking out is like leaving a hole in a bucket of water,” McCullough said. “If the head is the only part of the body not covered, of course more heat will be lost through the head.”
Children should be bundled for frigid weather along the same principle as adults – with an even distribution of layered clothing over all body surfaces, McCullough said. Children have a higher surface area relative to their mass than adults, so they lose heat faster, McCullough said, but they offset that by having a higher metabolic rate when sedentary.