What country has the dirtiest bank notes?

As of recent studies, the United States has been cited as having some of the dirtiest bank notes due to the high volume of cash transactions and the extensive circulation of its currency. Research has shown that U.S. dollar bills often carry a variety of germs, including bacteria and viruses. Other countries, like India and Brazil, also report similarly high levels of contamination on their bank notes. The cleanliness of currency can vary widely based on usage, handling, and sanitation practices.