Air pollutants like sulfur dioxide and nitrogen oxides are causing problems across borders, not just in the areas where they are emitted. Many countries are now working together to reduce the amount of pollution that drifts into other nations. This shift in policy is driven by rising emissions, better monitoring, and a deeper understanding of how pollution travels and affects health. While some regions lack international agreements on air pollution, others have multiple agreements in place. Air pollution is a serious issue, causing millions of deaths each year and significant damage to crops.