The New York Times is reporting a number of companies have increased the production of dangerous chemicals in order to profit from the carbon credits earned by reducing the pollution they cause. Since 2005, manufacturers of gases used in air-conditioning and refrigeration have sharply boosted their production of a waste gas just to obtain the large number of credits they get for ultimately destroying it. The credits have then been sold to other polluters, yielding earnings of tens of millions of dollars a year. The United States and European Union have taken recent steps to thwart the scheme, but critics say it has become so pervasive it could be difficult to slow down.