Note: The following article was taken from China Daily. If you compare modern photographs of colleges in the English university city of Oxford, with those taken little more than 50 years ago, you will instantly notice a remarkable difference. Today the picturesque sandstone buildings are a near pristine golden yellow in color, but, before the passing of the Clean Air Act in the UK in 1956, they were more or less uniformly black. Years of choking fumes from open fireplaces in