The masks came out again this month—only, contrary to the covid years, New Yorkers donned them outdoors and slid them off when they stepped inside. As smoke from hundreds of Canadian wildfires drifted across the northern U.S. border, engulfing much of the eastern seaboard in an orange miasma, it sent New York’s air quality to the worst levels on record, and, at one point, the worst in the world.