New Pope Smell

Most people know (and enjoy) the smell of a car fresh off the assembly line. Avid book readers know the comforting paper-and-ink smell of a new book, and every parent can identify the milky scent of a newborn baby’s head. But what does new pope smell like?

After the passing of the pope, the College of Cardinals gathers in Rome to elect his successor. The process, known as the papal conclave, is an intense period of discussion, meditation and prayer, during which the cardinals attempt to divine the will of God. Upon reaching a decision, the joyous event is signaled to the world through the release of white smoke out of the Sistine Chapel’s chimney.

During the conclave, the chimney oozes a sooty black smoke composed of sulphur, anthracene (derived from coal tar) and potassium perchlorate (an oxidizer commonly found in fireworks). From this, we can deduce that the lack of a pope smells like bad eggs on the Forth of July.

The white smoke, however, is produced using potassium perchlorate and lactose (to initiate combustion) and pine resin. Pine resins are composed of terpenes, organic molecules built mainly of carbon and hydrogen atoms. Without sufficient oxygen present, these terpenes undergo partial combustion, producing small carbon particles (soot) and a flurry of volatile compounds known as resin acids. In other words, the resin makes smoke - white smoke. This smoke is, of course, accompanied by the sweet, pleasant smell of . . . pine.

Brian Rutter, PhD, is the cofounder of Hundredfold Video and plant biologist working for 2Blades at the University of Minnesota. Subscribe to our newsletter to receive our “Sower Stories – Odd Facts About Plants” and video production tips in your inbox every month!

Works Cited:

Ball Philip. “Science behind the Vatican’s smoke signal explained.” BBC, 12 March 2013, https://www.bbc.com/future/article/20130313-science-behind-vaticans-smoke, Accessed 28 April 2025.