The hazy, orange skies hanging above cities in the Western United States this week have cast another layer of pall over an already unsettled sports world. San Francisco 49ers coach Kyle Shanahan described the scene at practice this week as looking like an “apocalyptic state.”

Experts in climate science and epidemiology say sports organizations and fans should get used to it. Major weather events like the wildfires burning in California, Oregon and Washington this week — which forced the postponement of one women’s soccer game Saturday — are expected to have an increasing impact on sports in the years to come.

The NFL, MLB, MLS and NWSL all spent time this week monitoring the air quality near game sites along the West Coast. The NWSL and the clubs agreed to postpone the Portland Thorns’ home opener against OL Reign on Saturday, when the city’s air pollution levels were consistently in the “very unhealthy” range on the scale set by the Environmental Protection Agency (EPA).

Projected air quality levels in Los Angeles and the Bay Area, where other leagues plan to host games this weekend, hovered in ranges that could cause health problems for some people but are considered generally safe for outdoor activity. Teams and leagues planned to continue monitoring those levels and could change plans up until game time.

More than 4.5 million acres of land in the U.S. have been torched by wildfires so far this year. The annual number of days with “extreme fire weather” in California has more than doubled since the 1980s, according to a study published earlier this week. The huge plumes of smoke from those fires can create unhealthy air conditions for large swaths of the surrounding area. In California and other Western states, the number of days when the air has been deemed unhealthy or hazardous to breathe has risen sharply over the past five years, according to data gathered by the EPA.

Climate scientists say those numbers are going to continue to worsen in the foreseeable future. Maddy Orr, an assistant professor at SUNY Cortland and co-director of the Sport Ecology Group, says sports leagues need to be doing more to prepare for the problems that will come from a changing climate.

“I can unequivocally say that there will be more fires moving forward. All the evidence suggests that it’s only going to get worse because things are getting dryer, it’s getting hotter, and when you put those factors together you get fire,” Orr said. “American pro sports leagues are really far behind, frankly, when it comes to policy change on these issues.”

The Air Quality Index is a 0-500 scale created by the EPA to measure a variety of pollutants in the air. Anything above 200 is considered “very unhealthy,” but risks start to increase for even elite athletes at lower levels on the scale. People with asthma or other health conditions may start to notice problems in the 100-150 range. In the 150-200 range, those people might experience serious health issues and others without preexisting conditions will start to feel the effects of poor air.

When the air quality rises above 200, trying to exercise outside would feel like running wind sprints in a smoke-filled bar, according to Roby Greenwald, an assistant professor at Georgia State who studies air quality epidemiology.

The NFL’s game operations manual says the league “will be prepared to relocate a game if there is definitive evidence that the AQI will remain consistently above 200 for a significant period of time, including the day of the game being played in the affected stadium.” The decision to move or postpone a game can be made right up until kickoff. An NFL spokesman declined to answer questions about when the policy was put in place or how it was formed. While the decision to change plans ultimately is made by the commissioner, it’s the result of an ongoing conversation among the league office, local health officials in the host city and representatives from the NFL Players’ Association.

Some changes were made to preseason practice schedules for teams in California due to the air quality, according to Sean Sansiveri, the NFLPA vice president who oversees health and safety. Sansiveri said he knows this will become a regular annual conversation moving forward and the union has had no issues to date with how the league has handled air quality threats, “but that doesn’t mean it’s not going to improve as these issues continue to arise.”

The MLB league office directs teams hosting games to follow the advice of local government agencies, according to a league spokesman. The MLS does not have a formal policy but usually starts to evaluate its options when the AQI level rises above 150 near a game site. The NWSL starts to consider postponements when levels are in the 180-200 range.

California Occupational Safety and Health Administration (OSHA) regulations passed last year dictate that employers must provide respirators (N95 masks) to their workers when the AQI goes above 150. Dr. John Balmes of the California Air Resources Board said that provision was put in place largely to protect farmers and construction workers who are doing some type of physical activity outdoors. Balmes said he imagines pro football players could “probably tolerate” slightly higher levels because in general not many in the population have preexisting heart and lung issues.

Greenwald, the Georgia State epidemiologist, says exercising in areas with less intense air pollution is safe, but researchers have not yet had the opportunity to study whether the type of exertion expected from athletes would create additional problems during extreme air pollution scenarios like a wildfire.

“When you’re doing physical activity, of course, the amount of air that you inhale goes up,” Greenwald said. “And so you’re getting a larger amount of air pollution inside your body, and you would expect that maybe that would have bigger health effects.”

Medical experts say it makes sense for leagues to avoid a hard-and-fast AQI number for postponing games because there is some ambiguity on when poor air quality can cause problems for different individuals. The wiggle room allows leagues to consider a variety of factors that could impact the level or risk posed to athletes and fans. For instance, some studies published this year have shown that exposure to poor air quality might raise the risk of death or other serious problems for people who contract the coronavirus.

Nick Watanabe, an associate sports management professor at the University of South Carolina, says while some flexibility is a good thing most pro leagues would benefit from a better-defined plan for dealing with air quality problems in the future.

“These policies probably need to be more detailed than just slapping a number down,” Watanabe said. “On one hand, the NFL has done a good job because they’ve started to put these policies into place. On the other hand, I think they could add more detail to really implement something that protects both their fans and the players.”

Watanabe and medical experts said exposure to poor air quality poses short-term and long-term health threats. Studies have shown it can also impact performance for both the athletes and the referees or umpires officiating their games.

Looking into the future, the experts who study the impact climate change will have on sports say there are multiple ways that leagues and teams can start to brace for inevitable problems. Along with creating more robust or clearer policies, Orr said sports organizations can start to build facilities that are equipped to withstand extreme weather or, in the case of wildfire risk areas, come with improved air filtration or air exchange systems. She said weeks like this one also present opportunities to raise awareness and provide better education to athletes, coaches and fans about the risks approaching their doorstep.

Orr says she hopes warnings like this weekend are enough to effect change but fears it will take a more tangible problem to push many in the sports world to act.

“Unfortunately, I think it’s going to come down to the bottom line financially,” she said. “And I think it’s going to take you know one or two really bad incidents or one or two really bad lawsuits or one or two really bad game cancellations for people to start looking around and say, ‘Oh shoot, this is happening a lot.’ When that starts to happen we’ll see the needle move.”