USC researchers help clean air around da Vinci's 'Last Supper'

You can breathe some pretty clean air if you get to stand in front of a 15th-century masterpiece in Milan. USC researchers are looking into how to keep it that way.

With timed reservations and limited ticketing, it ain’t easy for tourists to glimpse Leonardo da Vinci’s Last Supper in the monastery of Santa Maria delle Grazie. Costas Sioutas, who teaches at USC’s Viterbi School of Engineering, says that’s to protect the painting and keep pollution out. Sioutas got a rare view around its back when he installed pocket-sized air monitors on the wall below the 15th-century masterpiece.

"Very few monitors are so small in size and have such a noise level, so they wanted something very small, discreet," Sioutas said.
It doesn’t interrupt the day-to-day operations of such a sensitive facility. And by the way, it’s battery operated."

Italian museum authorities engaged the services of USC and Sioutas to determine how well a sophisticated air filtration system would cut pollution in the room. He says the monitoring system he installed in Milan was designed to measure air pollution inside Metro subway and light rail trains in Los Angeles County.

"This device actually allows you to classify particulate matter into different size ranges," Sioutas said. "We can also determine the chemical composition. This is what determines our sources."

What he found is that the filters reduce airborne pollution, big particles and small ones, by 80 to 90 percent inside the facility. Sioutas says pollution from indoors, some of it from surprising sources, remains a threat.

"Cleaners and fire retardants — also, believe it or not, some of the stuff from skin flakes, we ourselves emit some particulate matter, oils, waxes," Sioutas said. "Frankly, the painting itself."

People already pass through an airlock chamber to get inside the monastery’s dining hall. Visitors are limited to 15 minutes in front of "The Last Supper." What else can people do to minimize their impact?

"One simple example while I was there the last time was to put some simple adhesive layer on the floor," Sioutas said, "so that before the visitors actually go in, part of the dust that comes with them indoors actually gets taken up by this layer."

Sioutas says the success of his findings could help direct his team at USC toward a new line of work — measuring air pollution and improving air quality at museums.