08-09-2008, 12:54 AM
The WHO recommends levels below 50 for healthy air, while China considers anything above 100 to be harmful to sensitive groups including children and the elderly.
Posted on Fri, 08 Aug 2008 12:58:43 GMT at http://www.msnbc.msn.com/id/26089120/
Posted on Fri, 08 Aug 2008 12:58:43 GMT at http://www.msnbc.msn.com/id/26089120/