As flames rip through Los Angeles County, burning restaurants, businesses, and whole blocks of houses, it’s clear that the threat of urban fire has returned to the United States. But this time, the urban landscape is different: Modern homes are full of plastic, turning house fires into chemical-laced infernos that burn hotter, faster, and more toxic than their predecessors.
Firefighters are warning that the smoke pouring out of neighborhoods in Southern California is a poisonous soup, in part because of the ubiquity of plastics and other petrochemical products inside them. “It’s one of the reasons why we can’t put firefighters in front of these houses,” the Cal Fire battalion chief David Acuna told me on Monday. After any lifesaving work has been done, keeping firefighters in the toxic air is too great a risk.
Very few fixtures of the modern home are entirely free of plastic. If your couch is like many available on the market today, it’s made of polyester fabric (plastic) wrapped around polyurethane foam (plastic). When polyurethane foam burns, it releases potentially deadly hydrogen-cyanide gas. Perhaps those plastic-wrapped plastic cushions sit on a frame of solid wood, or perhaps the frame is made from an engineered wood product held together with polymer-based glues (plastic). Consider, too, the ubiquity of vinyl plank flooring, popular for its resistance to scuffing, and vinyl siding, admired for its durability. Then there is foam insulation, laminate countertops, and the many synthetic textiles in our bedding and curtains and carpets. Nearly all house paint on the market is best understood as pigment suspended in liquid plastic.
Research has long shown that exposure to the tiny particles that make up wildfire smoke is a major health hazard; as I’ve written before, wildfire smoke kills thousands of people prematurely each year and is linked to a range of maladies. Burning trees release gases such as carbon monoxide and carbon dioxide, along with tiny solid particles called PM2.5, which can penetrate deep into a person’s lungs and circulate in their blood stream, and are linked to heart and lung problems, low birth weight, preterm birth, and cognitive impairment. A burning town takes many of the chemical hazards of a burning forest and adds in a suite of new ones, Nadine Borduas-Dedekind, an atmospheric chemist at the University of British Columbia, told me. As structure fires eat through the plethora of materials inside a home, they can release not just hydrogen-cyanide gas but also hydrochloric acid, dioxins, furans, aerosolized phthalates, and a range of other gaseous contaminants broadly known as volatile organic compounds. Some may be harmless. Others are associated with health problems. As gas-detection technology improves, “we’re discovering new molecules of incomplete combustion that we didn’t know existed,” Borduas-Dedekind said. “When you’re burning a home or an entire neighborhood, we don’t have a handle on the breadth of VOCs being emitted.” And many of these can react with one another in the atmosphere, creating yet more compounds. Whereas N95 masks are good for filtering out the fine particles associated with fire smoke, they do nothing for these gases; only a gas mask can filter them out.
Plastic is made from petroleum, and petroleum burns fast and hot. A retired Maryland state fire marshal told Newsweek that, from a fire perspective, a typical couch is akin to a block of gasoline. Acuna invited me to think of placing a log on a campfire: It takes some time to heat up, charring first. It eventually ignites and becomes a steady fire, releasing its heat at a slow, consistent rate over, say, 20 minutes. If you threw a two-liter soda bottle on a campfire (which is a highly inadvisable thing to do), it would begin to distort immediately. Within several seconds it would ignite and burn fast.
In 2020, the Fire Safety Research Institute set two living rooms on fire, on purpose. Both were identical in size and full of furnishings in an identical arrangement. But in one room, almost everything was synthetic: a polyurethane-foam sofa covered in polyester fabric sat behind an engineered-wood coffee table, both set on a polyolefin carpet. The curtains were polyester, and a polyester throw blanket was draped on the couch. In the other room, a wood sofa with cotton cushions sat on a hardwood floor, along with a solid-wood coffee table. The curtains and throw blanket were cotton. In the natural-material room, the cotton couch appeared to light easily, and then maintained a steady flame where it was lit, releasing little smoke. After 26 minutes, the flames had spread to the other side of the couch, but the rest of the room was still intact, if smoky. Meanwhile, in the synthetic room, a thick dark smoke rose out of the flame on the polyester couch. At just under five minutes, a flash of orange flame consumed the whole room all at once. “Flashover,” firefighters call it—when escape becomes impossible. In the natural-material room, flashover took longer than 30 minutes. Perhaps that difference helps explain why, although the rate of home fires in the U.S. has more than halved since 1980, more people are dying in their homes when they do catch fire.
When I spoke with Acuna, of Cal Fire, he was sitting in his office, fielding calls from reporters. He looked around the room. “I’m struggling right now to find anything that is of a natural material. In fact, the only thing I can find is my notebook,” he said. Plastic, he added, is undeniably useful. But it comes with a clear risk. One day, if fire strikes, “it will burn faster, and it will burn hotter.” The advantages will turn to threats.
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