Think twice before tossing these things in the fire—they could poison your air and damage your lungs.
Lighting up a fireplace or backyard fire pit feels like pure comfort—until you realize what’s actually going up in flames. Most people think if it burns, it’s fair game. But experts are waving red flags over what we’re casually tossing into the fire. From old magazines to pressure-treated wood, the smoke you’re breathing in could be laced with toxins you’d never knowingly inhale. It’s not just bad for your health—it’s rough on your chimney, bad for the environment, and dangerous for kids and pets nearby.
1. Burning pressure-treated wood can release toxic chemicals into your lungs.
You might think repurposing old deck boards or construction scraps in your fire pit is a clever way to clean up, but pressure-treated wood is no friend to fire. This stuff is saturated with chemicals like arsenic, chromium, and copper to prevent rot and insect damage. When burned, it releases those same chemicals into the air—and you end up breathing them.
Even worse, those toxins don’t just float away. They settle on your skin, your clothes, and the ground where your pets and kids might play. It might just look like another log, but this one comes with invisible hazards. A cozy evening around the fire shouldn’t involve inhaling carcinogens, so it’s worth double-checking your firewood pile before you light up.
2. Tossing in colored paper can coat your home in harmful metal particles.
Holiday wrapping paper, flyers, party décor—it’s all just paper, right? Not quite. The bright inks, foils, and coatings on colored paper contain heavy metals like lead, chromium, and cadmium. Burning them releases fine particles that float into your living space and cling to surfaces. You might not see them, but you’re definitely inhaling them. And if you’ve got kids or pets nearby, that risk doubles.
Plus, all that gunk lines your chimney, upping your risk of a chimney fire. So that impulse to burn old gift wrap for fun or convenience? Not worth it. A trash bin or recycle bin is where that flashy paper belongs—not the flames.
3. Burning trash can turn your fire into a chemical disaster zone.
It might feel satisfying to toss everyday garbage into a backyard blaze, but burning trash is a straight-up recipe for toxic chaos. Plastics, food wrappers, and old packaging are loaded with synthetic compounds that release carcinogens like dioxins and furans when burned. That black smoke you see isn’t just ugly—it’s hazardous. You’re essentially building a mini hazardous waste incinerator in your yard. Plus, it’s illegal in many places, with good reason.
The environmental damage and health risks are serious. Even paper products in your trash might be coated with chemical residues. If you care about your lungs, your neighbors, and the planet, keep the trash far away from your flames.
4. Green wood might look harmless, but it creates a dangerous smoke storm.
Freshly cut wood seems like the obvious choice for a cozy fire—especially if it’s from your own yard. But “green” or unseasoned wood still contains a ton of moisture, and that spells trouble when it hits the flames. It doesn’t burn cleanly. Instead, it hisses, smokes, and releases creosote, which builds up in your chimney and can trigger a chimney fire.
Even worse, the thick smoke it produces is loaded with irritants that can trigger asthma or respiratory issues. Just because it’s natural doesn’t mean it’s safe to burn. Always let your firewood season for at least six months before throwing it on the fire. Trust me, your lungs—and your chimney—will thank you.
5. Tossing in cardboard might seem fine, but it pollutes more than you think.
Everyone’s done it—throwing a pizza box or Amazon package into the fire to watch it flame up fast. But burning cardboard is far more harmful than it looks. Most boxes are printed with inks and coated with adhesives that give off toxic fumes when burned.
Some also contain synthetic glues and plastic fibers. That quick blaze sends all those pollutants straight into your airspace, and you’re breathing them in whether you’re indoors or outside. Plus, flaming bits of cardboard can fly out of the fire and start a real fire hazard. Recycling is a far better fate for that box. Skip the smoke show and do your lungs a favor.
6. Painted or stained wood releases fumes that can make you sick.
Old furniture scraps or leftover construction wood might seem like perfect kindling—but if it’s painted or stained, it’s a big no. Paints and finishes often contain volatile organic compounds (VOCs) and heavy metals that don’t just disappear in the flames. They vaporize, releasing toxic smoke you do not want in your lungs. Lead paint? That’s even worse.
And even water-based stains can be harmful when burned. It might smell “woody” or even nostalgic, but what you’re inhaling could cause headaches, dizziness, or worse. Bottom line: if you wouldn’t roast marshmallows over it, don’t throw it in your fire.
7. Wet leaves might smell earthy, but they create harmful smoke and soot.
Those damp fall leaves might seem like free fire starter, but burning them is both illegal in some areas and terrible for your air quality. Wet leaves create thick, smoldering smoke packed with particulate matter that aggravates asthma and heart conditions.
They also produce benzene and formaldehyde—yep, the same stuff used in embalming fluid. It’s not the kind of ambiance you’re going for. That smoke clings to clothes, seeps into homes, and irritates your eyes and lungs. Plus, burning leaves releases carbon monoxide, especially dangerous in enclosed spaces. Raking and composting is the smarter move. Save your fire pit for actual firewood.
8. Styrofoam turns your fire into a cocktail of cancer-causing chemicals.
Styrofoam cups, takeout containers, or old packing materials should never meet a flame. When burned, Styrofoam releases styrene gas—a chemical classified as a possible human carcinogen. The fumes are not only hazardous to inhale but also linger in the air and settle into soil and surfaces. You might not notice the effects immediately, but regular exposure can take a real toll. That quick, bright flare-up may seem fun, but it’s anything but safe.
It’s also terrible for the environment. Styrofoam doesn’t break down cleanly, and burning it just turns the problem airborne. Toss it in the trash instead—not the fire pit.
9. Dryer lint soaked in synthetic fibers or scented sheets is toxic in flames.
Dryer lint might seem like a firestarter hack—and sure, it catches quickly. But if your laundry includes synthetic fabrics or you use scented dryer sheets, that fluffy lint is full of chemicals. Burn it, and you’ll release VOCs, phthalates, and other toxins right into the air.
Those fresh-smelling residues aren’t so friendly when they’re airborne. It might be tempting to scoop lint into your fire pit, but you’re better off composting it if your clothes are made of natural fibers—or just tossing it in the trash. That little lint ball carries more risk than you think. And it’s just not worth breathing in the side effects of your last laundry cycle.