You are! First off, handkerchiefs are less hygienic than single-use tissues. When you blow your nose in a handkerchief, you’re providing a fresh influx of snot to any germs already there. If these germs are viruses, the protein in your snot can help protect them from drying out; if they’re bacteria, the extra moisture can help them to grow.
When you next use your handkerchief, any germs that survived from the previous use are transferred back to your hands, which will contaminate the next door handle you touch. You can do a lot to limit this spread by washing your hands every time you blow your nose, but this isn’t always practical. Far more hygienic is to use a tissue and then throw it out.
What’s more, handkerchiefs are worse for the planet, too. A 2012 study by environmental consultants Ecosystem Analytics found that the CO2 emissions and pollution produced during the manufacture of a cotton handkerchief outweighed any savings over its lifetime compared to disposable tissues, even if you kept the same hanky for nine years.
Handkerchiefs do have the advantage that you don’t have to stockpile them, but that’s about all they’ve got going for them. Still, we wouldn’t recommend stockpiling tissues – leave some for others!