1. Lithium-Ion Batteries
Lithium-ion batteries are among the top fire hazards in household trash. They’re found in a surprising number of devices — phones, laptops, e-cigarettes, power tools, kids’ toys — and if the casing gets punctured or crushed during garbage collection, they can short-circuit and ignite almost instantly. These fires are now common enough that many cities run public awareness campaigns and some waste haulers have changed their safety procedures in response.
Most communities offer battery drop-off sites at municipal recycling centers and hardware stores — many Home Depot locations, for example, are equipped with Call2Recycle bins that accept lithium-ion batteries. If a battery is built-in, select electronics retailers and local e-waste programs will often take the device as is, offering a safer alternative to the trash.
2. Aerosol Cans
Even a seemingly empty can of hairspray or spray paint may have some pressurized gas left inside, and those contents are flammable. Toss it in the trash, and a compactor can rupture the can and ignite the trapped gas. While some cities accept empty aerosol cans in curbside recycling, check your local rules first — or take them to a household hazardous waste collection site instead.
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3. Oily Rags
This one surprises people. Rags soaked in linseed oil, oil-based wood stains, varnishes, and polyurethane can spontaneously combust without an external heat source. As the oil oxidizes, it generates heat — and if the rag is balled up in a trash bag, that trapped heat can start a fire. Lay oily rags flat outdoors on a noncombustible surface, keeping them out of direct sunlight, to dry completely before disposal — or seal them in a metal container filled with water.
4. Old Paint and Paint Thinner
Leftover paint — especially oil-based — is considered household hazardous waste. It’s flammable and doesn’t belong in a landfill. Paint thinner poses an even greater risk because its vapors can ignite if a container leaks or is left open. Many municipalities hold household hazardous waste collection events throughout the year or have permanent drop-off facilities.
5. Propane and Butane Canisters
Small camping canisters and larger grill tanks shouldn’t go in household trash — most trash services won’t take them even when empty. Instead, drop off small canisters at a household hazardous waste collection site or take grill tanks to a retailer that offers propane exchange.
6. Lighters and Matches
A disposable lighter with fuel left inside can rupture and ignite if a spark is present when it’s crushed in a garbage truck. Take partially full lighters to a household hazardous waste collection site instead. As for matches, always soak them in water before throwing them away.
7. Broken Glass Thermometers
Older glass thermometers contain mercury (a silver liquid), which can be released if the glass shatters in the trash. Because mercury is highly toxic, these should always be taken to a household hazardous waste collection site. If your thermometer has red or blue liquid, it contains alcohol — not mercury — and can go safely into the regular trash. While alcohol is flammable, a thermometer doesn’t contain nearly enough fluid to catch fire inside a trash truck. Just remember to wrap the glass shards in something so they don’t tear the bag or harm the trash collectors.
Most household trash is harmless, but a few common items require special handling. Taking an extra 15 minutes to drop off batteries, old electronics, or leftover paint at the proper collection site helps prevent fires, protect sanitation workers, and keep hazardous materials out of landfills.
