Step 1: Understanding the Concept:
The question asks for the name of the main environmental body within the United Nations Organization (UNO).
Step 2: Detailed Explanation:
The principal body of the United Nations dedicated to environmental issues is the United Nations Environment Programme (UNEP). Established in June 1972 after the UN Conference on the Human Environment in Stockholm, UNEP is responsible for coordinating the UN's environmental activities. Its mandate is to provide leadership, deliver science, and develop solutions to a wide range of environmental issues, including climate change, biodiversity loss, and pollution. Its headquarters is in Nairobi, Kenya.
Step 3: Final Answer:
The name of the environmental unit of the UNO is the United Nations Environment Programme (UNEP).