London is breathing easier: deaths linked to air pollution have fallen by 40%, according to a new study from Imperial College, marking a major public health victory for the capital.

The dramatic decline reflects years of targeted policies and cleaner technology. However, researchers also discovered that air pollution remains more harmful to human health than previously understood—a sobering reminder that even improved air quality demands continued vigilance. Read the full story →

Today's takeaway: Progress on pollution shows that environmental policy works—but the job of protecting public health is far from finished.