Each year, as dry seasons settle over the Indonesian archipelago and fires consume Sumatra and Kalimantan, the smoke does not stay where it begins — it travels, carried by wind across borders and into the breathing spaces of millions. Singapore, a city-state of extraordinary density and order, found itself once again reminded that the air it shares with its neighbors cannot be governed by any single authority. After briefly crossing into unhealthy pollution levels for the first time in nearly three years, the city exhaled a cautious relief on Saturday morning — though the fires that caused the