Richard Skolnik, lecturing for Yale's Essentials of Global Health course, examines how environmental conditions shape disease and mortality worldwide. He covers air and water pollution, sanitation, indoor cooking smoke, and climate change as drivers of respiratory illness, diarrheal disease, and other health burdens, with particular attention to how these risks fall hardest on low income countries. The lecture ties environmental exposure to broader global health metrics, showing how contaminated water supplies and poor waste management translate into measurable disease rates. Skolnik frames the material as one of several cross-cutting themes in the course, alongside humanitarian emergencies and nutrition, and uses data and examples to explain why environmental health interventions, like clean cooking fuel or water treatment, are treated as core public health priorities rather than side issues. The session runs about twenty five minutes and functions as a self-contained overview of the topic within the larger course.