On the afternoon of January 27, 1967, three American astronauts, clad in space suits, boarded the Apollo 1 test capsule for a simulated liftoff. The hatch was sealed, pure oxygen was pumped into the cabin, and the routine countdown procedures got underway. Suddenly, the crew’s biomedical readings skyrocketed, and sensors detected a brief power surge. Then came a frantic report from inside Apollo 1.

“Fire! We’ve got a fire in the cockpit,” yelled pilot Roger Chaffee, “we’re burning up.”

Outside the capsule rescuers were stopped from reaching the escape hatch by heat and heavy gray smoke,” Twenty-seven of them would succumb to smoke inhalation. But the real horror came when teams were finally able to open the hatch of Apollo 1, a full five minutes after Astronaut Chaffee’s initial shout.

The interior of the command module was a scene of charred devastation. Gus Grissom, Ed White and Roger Chaffee had perished. Investigators later found the fire was started by a spark from an electrical short circuit fed by pure oxygen, and a fuel supply of nylon nets and polyurethane panels an inferno took hold. For the crew, shrouded in toxic smoke there was no escape.

After the astronauts were laid to rest, NASA set to work. U.S. Air Force pathologists conducted examinations, concluding that the astronauts died of asphyxia from carbon monoxide and other toxic gasses resulting from the fire. The burns they received were likely survivable.

The use of plastics had come close to derailing America’s lunar goals. Combined with spark and heat, they had shown their lethal capabilities. Over the next year, wool was introduced as a fire retardant, wire bundles were encased in metal, and nylon was eliminated. Pure oxygen was replaced with a more stable nitrogen and oxygen mix, and a single-piece hatch was installed that could be sprung in seconds with a push from an astronaut’s pinkie.

While the space program recognized the problems with plastics, the military continued to advance with synthetic materials. In the 80’s and 90’s new synthetic fabrics were all the rage. Chemical companies were spinning out nylon, rayon, and polyester for new uniforms and combat clothing. The gear from these fibers didn’t feel good or breathe, but the military was attracted to more affordable uniforms that were easy to care for, wrinkle-free, and rugged. Later, synthetic fabrics like Gore-Tex offered breathability and waterproofing, and polypropylene was introduced as a miracle fiber for base layers.

By 2003, synthetic clothing technology had been integrated into military uniforms. However, as combat operations began in Iraq and Afghanistan, two significant issues with synthetic base layers emerged.

“The first was that synthetic athletic apparel took on a permanent stink,” explains Mitch Driggers, a textiles engineer and retired US Air Force Lt. Colonel. “Soldiers complained that their synthetic base layer clothing quickly developed an intolerable odor that persisted even after washing.”

According to Driggers, the second problem was far more severe. During combat missions involving high exposure to blasts, heat, or flame, the synthetic base layers would literally melt into the soldiers’ skin.

The hard lessons learned from the space program and military offer important insights for consumers as well. The durable and waterproof capabilities of synthetics have made them an affordable and long-lasting option for apparel and equipment in the outdoor adventure and leisure markets. However, these materials carry significant risks.

Our boats, RVs, and backpacks, campsites are literally stuffed with petroleum-based materials that ignite easily, burn furiously, shed toxic smoke, and melt to the skin. When exposed to high temperatures, sleeping bags, tents, and clothing made from nylon, acrylic, or polyester will ignite, melt, and produce a hot, sticky substance that causes severe burns.

“It should be safety first, but it’s comfort and low prices that shoppers seem to focus on,” says Driggers. But he notes that change is on the way. In the civilian world, Merino Wool products from companies like SmartWool have gained popularity. Driggers points out, “There was no wool fabric at the major outdoor retailer shows 15 years ago. At an outdoor show now, mixed in with the synthetics, you’ll find a multitude of wool and wool/synthetic blends.”