By Deborah Franklin, NPR

Staying snug within a watertight tent as a storm rages around you is one of the joys of modern camping and modern tents.

But if the weather suddenly turns nasty on your next camping trip, or nights are just colder than you expected, don’t be tempted to bring your cook stove inside. Levels of poisonous carbon monoxide (CO) from the burning stove can build up fast.

That’s the warning from several Michigan emergency room doctors who wanted to know if varying the type of stove fuel might make a difference in such situations. They also wondered if the more rugged, four-season tents favored by those who like to be ready for anything would raise the concentration of carbon monoxide more than airier three-season versions. Quick answers from their small, first-pass test: Yes and yes.

All in the name of science: Volunteers hike in Colorado during their one-week hiatus from electrical lighting.

“Four-season tents are built really well to keep out the elements,” says David Betten, a medical toxicologist in the Department of Emergency Medicine at Sparrow Hospital in Lansing, Mich. “Unfortunately, that same tight construction means they’re not all that well ventilated.”