Thick, acrid smoke from Canadian wildfires has blanketed the eastern United States, casting a pall over preparations for the World Cup final scheduled for Sunday in New Jersey. The hazardous air quality forced residents in New York, Washington, and parts of the Midwest to remain indoors, disrupted team training sessions, and left tournament organizers closely monitoring conditions. Main Developments On Saturday, New York City briefly became the most polluted city in the world, according to air quality tracker IQAir, followed closely by Toronto and Washington. The smoke obscured the city skyline, and people wore masks outdoors as air quality readings plunged into dangerous territory. The World Cup final between Argentina and Spain will be played at an open stadium in New Jersey, directly across the Hudson River from Manhattan. Tournament organizers are “monitoring closely,” said Andrew Giuliani, executive director of the White House World Cup task force, during a briefing. Read also: Why Latin America Rallies Against Argentina in World Cup Finals Heavy thunderstorms forecast for Saturday afternoon in the New York area offered a potential reprieve, as rain could wash some smoke from the air. However, New York Mayor Zohran Mamdani warned that the storms could also trigger flash flooding and damaging winds strong enough to down trees and power lines. Background More than 950 wildfires were burning across Canada as of Saturday morning, according to the Canadian Wildland Fire Information System. The smoke has drifted south across the border repeatedly in recent years, creating recurring public health emergencies in U.S. cities. President Donald Trump has blamed Canada for the smoke pollution, threatening additional tariffs and accusing the country of “willful negligence” by “not properly maintaining” its forests. Meanwhile, advocates have stressed the connection between repeated wildfire smoke episodes and climate change. Why It Matters The hazardous air quality poses direct health risks for millions of people, particularly children, the elderly, and those with respiratory conditions. The U.S. National Weather Service said smoke would continue to affect the area through Saturday afternoon, and in Washington, D.C., officials warned that air quality was “unhealthy for at-risk groups.” The disruption to a marquee global sporting event like the World Cup final highlights the tangible consequences of climate-driven wildfire seasons. It also underscores the policy tensions between the U.S. and Canada over transboundary pollution. What's Next Forecasters expect the incoming thunderstorms to temporarily improve air quality by clearing some smoke, though the storms themselves bring risks of flash flooding and high winds. Tournament officials have not announced any changes to the match schedule but continue to monitor conditions. The long-term outlook depends on whether Canadian fire crews can contain the hundreds of active blazes.