Your Dollar Bills Harbor 3,000 Types of Bacteria

The next time you hand over a crisp dollar bill, consider this: you're not just passing currency—you're exchanging a thriving microbial ecosystem. Researchers at New York University analyzed 80 one-dollar bills and discovered roughly 3,000 different types of bacteria living on each one.

That's not a typo. Three thousand. Your wallet is basically a mobile petri dish.

What's Actually Living on Your Cash?

The bacterial lineup reads like a greatest hits album of germs you'd rather avoid. Scientists have found bugs linked to pneumonia, food poisoning, staph infections, and acne just chilling on ordinary bills. In one study, 94% of tested dollar notes were harboring bacteria, including some nasty enough to cause serious infections.

Some specific troublemakers identified include:

• Staphylococcus aureus (including antibiotic-resistant strains)
• Escherichia coli (yes, that E. coli)
• Klebsiella pneumoniae
• Pseudomonas aeruginosa

But here's where it gets interesting: lower-denomination bills are the dirtiest. Your ones, fives, and tens get passed around more frequently than bigger bills, making them bacterial breeding grounds. That crumpled single at the bottom of your pocket? It's seen some things.

Why Dollar Bills Are Bacterial Magnets

American currency has a unique problem. Unlike the slick polymer bills used in Australia, Canada, and the UK, U.S. dollars are made from 75% cotton and 25% linen. This fabric blend creates a porous, textured surface that bacteria absolutely love.

Cotton fibers trap moisture and provide plenty of nooks and crannies where microbes can settle in for the long haul. Some bacteria can survive on bills for weeks—Staphylococcus aureus can hang out for over 19 days, while flu viruses (when accompanied by mucus) can survive up to 17 days on certain currencies.

Should You Panic and Go Cashless?

Before you swear off physical money forever, here's the twist: money is actually terrible at transmitting diseases. Yes, it's covered in bacteria, but that same porous surface that traps microbes also prevents them from easily transferring to your hands.

Current research suggests that banknotes and coins don't pose a significant infection risk to the general public. The bacteria are there, sure, but they're mostly just along for the ride. Your phone screen, keyboard, and kitchen sponge are probably bigger health concerns.

That said, washing your hands after handling money is still smart hygiene—especially before eating. Those 3,000 bacterial roommates on your dollar bill might not jump ship easily, but why take chances?

Next time someone says "money is dirty," you can hit them with the exact number: roughly 3,000 types of dirty, give or take a few hundred microbes.