At the height of the COVID-19 lockdowns, traffic was pretty light. So was the air: light and relatively lower in pollutants than when the economy was going full-throttle.
Scientists have marveled at the reduction in emissions produced by the lack of human activity, and they've put research papers out to quantify the differences.
Rob Jackson at Stanford University is one of the scientists studying the changes and the implications for pollution and climate change. He visits to give texture and detail to the changes in the air.