【科普知识型---阅读理解】
Housed in Milan, one of Europe's dirtiest cities, Leonardo da Vinci's masterpiece The Last Supper still faces a threat from air pollution, researchers say, despite preventative measures that have significantly decreased pollutants in the church where the famous painting is on display.
In 2009, Italian authorities installed a heating, ventilation (通风) and airconditioning system to protect the painting from Milan's polluted air. To see whether the system could improve air quality, a team of researchers led by Constantinos Sioutas, a professor of civil and environmental engineering at the University of Southern California, placed two airquality monitors inside the church for a year to collect samples from around painting. Results showed the levels of fine and coarse particulates were reduced near the painting by 88 percent and 94 percent, respectively, compared with the corresponding outdoor levels. “It's a spectacular reduction，” Sioutas said in a statement. “It is, frankly, very impressive.”
