Environmental impact assessments started in the 1960s, as part of growing understanding of the environment. EIAs included a professional evaluation intended to lead to a more informed decision taking process. Environmental impact assessments in the United States received legal recognition in 1969, with the National Environmental Protection Act being passed.
EIAs were increasingly being used around the world. This year, the number of environmental assessments submitted "has greatly surpassed the amount of more rigorous environmental impact statements." EIA is an activity that is undertaken to evaluate the impact that will be made before construction takes place.
Environmental Assessment (EA) is an environmental impact assessment of a plan, policy, program or actual project prior to the decision to move forward with the proposed action. The term "environmental impact assessment" is typically used in this sense when applied by individuals or organizations to particular projects and the term "strategic environmental assessment" refers to policies , plans and initiatives most frequently implemented by state bodies.It is an environmental management tool that forms a part of project approval and decision taking.
The aim of the evaluation is to ensure that policy makers consider the effect on the environment when determining whether to continue with a project or not. The International Association for Impact Assessment (IAIA) defines an environmental impact assessment as "the process to identify, predict, evaluate and mitigate the biophysical, social and other relevant effects of development proposals before major decisions and commitments are taken."