... kilometers of tunnels, 10-20 years of construction work, thousands of trucks trips for transportation of materials to and from the site, million tons of excavated material to be disposed of, thousands ... villas, churches and abbeys, castles and fortresses, which attract thousands of tourists every year. At the time of the Romans, the alpine crossovers of the valley acquired strategic and military ... radioactive gas, and radon decay products. Radon is colorless, odorless, and chemically inert; it is formed by the radioactive decay of uranium in rock, soil, and water, and has a half-life of about...