The main research area of Stig Irving Olsen is environmental assessment of products and systems. This is for example assessments of how a product impacts the environment in relation to e.g. climate changes, toxicity and acid rain throughout the whole life cycle of the product. The life cycle of a product begins at the extraction of raw materials for example in mining and it ends when the product is worn out and ends its life at a landfill or in an incineration plant. Assessments of systems are alike but in stead of a product the object of assessment is a system like e.g. waste treatment systems or energy production systems. The latest years his focus has been on environmental assessment of micro/nano production. Products manufactured by micro/nano production are special because they are so small and therefore they often entails particular impacts like the use of scarce metals or the risks associated with nano particles.