Giant Helium Balloon in Paris Displays Air Pollution Levels

physorg.com — People in Paris won't have to look far to see the city's air pollution levels. A giant tethered helium balloon will display real-time reports of atmospheric pollution using an innovative lighting system, which can be seen from more than 20 km (12.4 miles) away. The balloon turns different colors depending on the air pollution levels. Jul 9, 2008 View in Crawl 4