Air Day
Air Day falls on November 11, marking the mixture that is mostly nitrogen, was made breathable by bacteria, and still kills millions a year when polluted.
2 holidays
Air Day falls on November 11, marking the mixture that is mostly nitrogen, was made breathable by bacteria, and still kills millions a year when polluted.
Origami Day falls on November 11, honoring a paper craft that turned out to contain serious mathematics and now folds solar arrays and heart stents.