The 2016 Environmental Performance Index (EPI), a Yale-based initiative that evaluates how 180 countries protect ecosystems and human health, finds cause for both optimism and serious concern. The world's nations have expanded access to water and sanitation while creating more protected areas than ever before, yet countries have failed to reverse degradation of air quality and decline in fisheries, the report finds. The EPI, which measures national and global protection of ecosystems and human health from environmental harm, draws out trends and highlights data gaps in priority areas including air quality, water management, and climate change.