Is it safe to burn cardboard?

Short answer

Why people ask this

People often have extra boxes and think cardboard is like wood or a convenient fire starter. They may want to dispose of it quickly in a fireplace, fire pit, or burn barrel without realizing the smoke, chemical coatings, and ember risks.

When it might be safe

There are no commonly accepted situations where this is considered safe.

When it is not safe

• Inks, glues, and coatings can release toxic fumes and soot when burned
• Lightweight pieces create flying embers that can start unintended fires
• Flattened boxes burn fast and hot, increasing flare-ups and loss of control
• Smoldering cardboard can boost carbon monoxide indoors
• Burning trash may violate local laws and result in fines

Possible risks

• Respiratory irritation, asthma flare-ups, and eye/throat discomfort
• Harmful pollutants like VOCs and PAHs from inks and coatings
• Chimney or stovepipe creosote buildup and potential chimney fires
• Outdoor spread to structures or vegetation, causing wildfires
• Legal penalties or liability for nuisance smoke or open burning

Safer alternatives

• Recycle clean, dry cardboard via curbside pickup or a drop-off center
• Reuse boxes for storage, moving, or donate through local groups
• Compost small amounts of plain, uncoated cardboard after shredding
• Use seasoned firewood and commercial fire starters instead of cardboard
• Break boxes down and give away on community marketplaces

Bottom line

Don’t burn cardboard. It can produce harmful smoke and stray embers and may be illegal. Recycle or reuse it, and use proper firewood and safe fire starters instead.

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