During the 1990s business and many governments have become strong proponents of voluntary approaches to reducing pollution in preference to mandatory regulation. To this end, significant work has been done to develop and promote programs aimed at supporting efforts by business to engage in more sustainable practices through better pollution prevention planning and the setting of sectoral emission reduction targets. Many businesses have also come to favour the concept of emission rights trading. Under an emssion "cap and trade " regime, governments identify key emission sources, set a limit or cap on overall emissions, and allocate a portion of that cap to each source. The idea is that putting a concrete value on the right to pollute, and allowing rights holders to sell these rights, strong incentives will be created for companies to reduce their emissions so that they can sell or save their pollution rights.
The concept of emissions trading remains controversial and untested in Canada although in the United States it has met with some success. The Ontario government has recently announced an emissions trading system that will allow the Ontario Power Generation corporation to meet newly imposed emission caps on acid gas by purchasing emission credits. This proposal has come under heavy criticism from environmental groups: see "Pollution Loopholes" at www.cleanair.web.net.