<http://schema.org/about>
"Yes, it's true that our air -- especially in smoggy cities like Los Angeles -- has gotten cleaner since important environmental legislation was passed back in the early 1970s. The EPA and the Clean Air Act have helped"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.treehugger.com/corporate-responsibility/us-had-2000-unhealthy-air-alerts-in-2011-so-far.html>