admium Levels in the Environment. Cadmium levels in the environment increased rapidly in the period from 1800 to 1960, due predominantly to industrialization in the Western World and the huge increase in fossil fuel combustion during that period and since cadmium is a naturally occurring impurity found in all fossil fuels. For the 50 years since 1960, cadmium levels in the general environment have been decreasing due to improved emission control for fossil fuel combustion and improved technology for the production, use and disposal of cadmium and cadmium-containing products. These trends are shown in Figure 2 below.w.