The biggest game in soccer is set for Sunday, when Argentina and Spain will meet in the World Cup final, held just outside of New York City. There’s just one problem. Wildfire smoke now threatens the match—and FIFA, the sport’s governing body, doesn’t appear to have any plan in place to protect the health of players or fans.

Wildfire smoke blowing from Canada has blanketed large swaths of the Midwest and East Coast in recent days, impacting more than a dozen states, with some of the worst-hit cities facing air quality in ranges considered hazardous. New Yorkers are among those who have been watching their air turn orange and hazy this week. On Thursday, the state issued an alert as the air quality index climbed to “unhealthy” and “very unhealthy” levels. “Avoid spending time outdoors, if possible,” officials advised.

As of Friday morning, air quality near the stadium remained in the unhealthy range, and while it’s forecast to improve to “moderate” by Sunday’s kickoff, smoke patterns could still change. If concerns continue during the finals, there’s no way to close off the open-air stadium where stars Lionel Messi and Lamine Yamal are slated to square off. That means fans and players would almost certainly be exposed to smoke, which could lead to symptoms such as a burning throat, coughing, or headache, among others. This can be particularly dangerous for sensitive groups, including children, older individuals, and people with respiratory conditions such as asthma.

Players have also practiced outdoors during air quality events in the lead-up to the game—the Spanish team held a practice Thursday in New Jersey. “These are high-level athletes who are moving a lot of air ...