Mount Pinatubo explodes. The stratovolcano's eruption was one of the most violent of the 20th century. About 800 people died, but the event had also global consequences. For example, it caused a global temperature drop of 0.5 °C (0.9 °F).
Spain holds the first free elections since 1936. The transition to democracy followed nearly four decades of right-wing dictatorship under Francisco Franco. Adolfo Suárez became Spain's first democratically elected Prime Minister.
Charles Goodyear patents vulcanization. The American inventor is credited with developing the basic concept of strengthening rubber by adding sulfur or similar materials. Vulcanized rubber is today used for a wide array of products, such as tires and shoe soles.
The first human blood transfusion is administered. Jean-Baptiste Denys, physician to King Louis XIV of France, transfused sheep blood into a 15-year-old boy. He survived, most likely due to the relatively small amount of blood used.