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Home > Guides > Shipping hazmat basics
More everyday items than you'd expect: aerosols, perfume, nail polish, some cleaning products, and lithium batteries all count as hazardous materials to a carrier. The rules exist because these items can catch fire, leak, or react in a truck or cargo plane. Carriers can refuse an undeclared hazmat package outright, and shippers face fines. LetterAgent labels are for ordinary parcels only: anything classified as hazardous material can't go on one.
| Item | Why carriers flag it |
|---|---|
| Aerosol cans | Pressurized: they can burst in heat or if crushed |
| Perfume and cologne | Alcohol-based flammable liquid |
| Nail polish and remover | Flammable solvents |
| Lithium batteries | Fire risk if damaged, shorted, or defective |
| Bleach and strong cleaners | Corrosive: they eat through packaging and skin |
| Lighters and matches | Ignition source |
| Dry ice | Sublimates into carbon dioxide gas, which builds pressure |
The rules split three ways. Batteries installed in the device they power, like a phone or a laptop, are the least restricted: the device itself protects them. Standalone batteries, like spares and power banks, face tighter limits on quantity and packaging, because loose terminals can short against metal. Damaged, swollen, or recalled batteries can't be shipped through normal channels at all: they need specialized hazmat handling. The distinction matters because most people mailing a phone are fine, while someone shipping a box of loose power banks is not. The rules are also stricter for air than for ground: a battery that's fine on a truck may be restricted on a plane.
Sometimes. Carriers recognize limited-quantity rules for small amounts of certain everyday hazmat, like a single bottle of perfume, but the package still needs the right marking, and the exception varies by carrier and by whether the parcel flies. Ground shipping is generally more permissive than air. Never assume the exception applies to your item: check the carrier's dangerous-goods guide for the specific product. In the US, the rules come from the Department of Transportation; in Canada, from Transport Canada's dangerous-goods regulations. The carrier's guide translates those rules into what you can actually drop off.
The best case is the carrier catches it and returns or destroys the package. The worse cases are fines and liability: if an undeclared item causes damage, the shipper is on the hook, and carriers take a dim view of surprises in their sorting facilities. Parcels are screened routinely, and a leaking or hissing package gets attention fast. When in doubt, declare it or don't ship it: there is no version where sneaking it through works out well.
This is general information, not legal advice.
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