The first example concerns the use of agricultural fuels and, in particular, the use of the so-called “biodiesel” in lieu of diesel fuel. The overall environmental impact of this product has been evaluated by examining all quantifiable effects. From an examination of the results, it can concluded that biodiesel is less detrimental than diesel fuel where the greenhouse effect, energy and non renewable raw materials and biodegradability are concerned. On the other hand, where all other aspects are concerned, its effects are equivalent or even more adverse.The second example deals with the evaluation of the impact on the environment of substances meant to replace CFC's both as expanding agents for polyurethane foams and as cooling fluids in air conditioning systems.The use of such subtonics has become necessary to prevent a further reduction in the ozone layer present in the stratosphere. Alongside this benefit, the evaluation of other environmental impacts has made possible to identify important additional benefits in the greenhouse effect.