Heat dome and Canadian wildfire smoke push NYC-area air quality to "Unhealthy" for all

A heat dome trapping temperatures above 90°F converged with Canadian wildfire smoke over New York City on July 17, 2026, creating a compounding health hazard. Long Island's AQI for fine particulate matter hit 195 — "Unhealthy," meaning the general population, not just sensitive groups, faces health risks. Mayor Zohran Mamdani urged residents indoors; the city distributed free KN95 masks citywide.