It was baseball as played in a sensory-deprivation tank. No smell of hot dogs or popcorn. A silence so pure you could hear the bullpen phone ringing from the dugout. Nothing but empty, green seats as far as the eye could see. It was still baseball, but a grotesque, distorted version that no one who was there, at Oriole Park at Camden Yards in Baltimore on April 29, 2015, ever wanted to witness again.

“Fans play such a big part in generating the intensity when you’re playing at home,” said Jim Palmer, a Hall of Fame pitcher across a 19-year career with the Orioles and now a television broadcaster who was in the booth that day, when civil unrest in Baltimore following the death of Freddie Gray forced the team to play a home game against the Chicago White Sox with no fans present. “All of that was gone.”

The question of whether a sporting event is still a sporting event if played without fans is suddenly and unsettlingly pertinent again this week as the major North American leagues, including the NBA, NHL and Major League Baseball, prepare contingency plans for the growing coronavirus outbreak.

It is a step that has already been taken in Europe, where top-level soccer matches in Spain, Portugal, France, Germany and Slovakia have been or will be played in empty stadiums. Italy, among the countries hardest hit by the coronavirus, has canceled all matches for the next month. In Asia, Japan’s Nippon Professional Baseball league and South Korea’s KBO have pushed back the starts of their regular seasons indefinitely.

American teams could be deciding soon whether to postpone or relocate games, or play them without fans. Chief among them are the NHL’s San Jose Sharks, who play in Santa Clara County in California, where public health officials, citing an increase in coronavirus cases and the dangers of community spread, have banned public gatherings of more than 1,000 people for three weeks. The countywide ban could affect three Sharks home games, as well as NCAA women’s basketball tournament games at Stanford and one home game of the MLS San Jose Earthquakes. The Mid-American Conference and Big West Conference announced Tuesday that their men’s and women’s basketball tournaments would be held this week without spectators.

Both the NHL and NBA are in the final weeks of their regular seasons, with the playoffs set to begin in April, adding a complicating factor to decisions about how to proceed in the event the outbreak gets worse. The NBA this week circulated a memo instructing teams to prepare for the possibility of games in empty arenas — a notion that initially did not appear to sit well with one star player.

“I play for the fans; that’s what it’s all about,” LeBron James said days ago. “If I show up to the arena and there ain’t no fans there, I ain’t playing.”

James clarified his comments Tuesday.

“It’s funny because when I was asked the question, ‘Would you play without no fans?’ I had no idea that it was actually a conversation going on behind closed doors about that particular virus,” James said. “Obviously I would be very disappointed, you know, not having the fans, because that’s what I play for. I play for my family. I play for my fans.

“They’re saying no one could actually come to the game if they go to that point, so I’d be disappointed in that, but at the same time, you got to listen to the people that are keeping track of what’s going on. If they feel that it’s best for the safety of the players, safety of the franchise, safety of the league to mandate that, then we’ll all listen to it.”

MLB, if only because its Opening Day is still more than two weeks away, is in a somewhat better spot, though league officials informed teams in a conference call Monday night to begin making contingency preparations for the possibility of the outbreak spreading. Baseball is also used to having individual teams’ schedules upended by weather, with Florida- and Texas-based teams occasionally having games moved to other locations.

An MLB spokesperson said Tuesday that no decision had been made on altering its schedule for the coronavirus, but that it would be moving forward on a team-by-team basis; in other words, the Seattle Mariners, whose home city is among the hardest hit in the United States, could require more urgent action than a team farther from an outbreak. At this point, MLB is more likely to move games — to spring training facilities in Arizona and Florida or minor league stadiums away from major outbreaks — than to play them in empty stadiums.

For U.S. sports, the situation is perhaps most reminiscent of the fall of 2001, in the aftermath of 9/11, when the NFL postponed Week 2 of its regular season, moving those games to the end of its schedule, and MLB took a six-day pause before resuming the final month of its regular season, with World Series games pushing into November for the first time.

The notion of games played in empty stadiums or arenas, however, goes against the very nature of sports as entertainment. For example, when it was determined it was too risky to bring massive crowds to the Coachella Valley Music and Arts Festival in mid-April, organizers postponed the event until October, rather than have the bands play to an empty California desert.

“It would be awful,” Washington Nationals first baseman Ryan Zimmerman, speaking before a spring training game in West Palm Beach, Fla., said of the possibility of playing in empty stadiums. “… We’re entertainers. That’s what we get paid to do. We enjoy playing in front of fans. Playing in an empty stadium — it’s hard enough to play [spring training games in front of] two, three, four, five thousand people.

“That’s why it’s so hard to play down here. You know the games don’t count, and there is no atmosphere. So having to play games that count in no atmosphere, I think the product would be tough. We’re all professionals, and I’m sure we would do it, but I don’t think it would be good.”

Staging games without fans also goes against the concurrent nature of sports as massive businesses. Although broadcast rights have long since passed ticket sales as the top revenue driver of professional sports, teams and leagues stand to lose untold millions of dollars with each gate that is lost.

That helps explain why, to this day, the April 29, 2015, game between the White Sox and Orioles in Baltimore remains the only game in major North American professional sports to have been played with no fans.

The decision came four days after Camden Yards was briefly placed on lockdown because of public-safety concerns near the end of an Orioles-Boston Red Sox game, when protests just outside the stadium became violent. In the aftermath, the first two games of a scheduled three-game series between the Orioles and White Sox were postponed until the following month, but MLB needed the third game to be played. (A subsequent three-game home series against the Tampa Bay Rays was moved to Florida.)

Because bringing tens of thousands of fans to Camden Yards in such an atmosphere would have required dozens of police officers who were needed elsewhere in the city, MLB made the decision — late in the afternoon the day before — to stage the game without fans. And because the city had implemented a 10 p.m. curfew, the game was moved to the afternoon. That left the Orioles with less than 24 hours to prepare.

Although team officials and stadium personnel tried to keep everything as normal as possible, from batting practice to the exchange of lineup cards to the playing of the national anthem, when White Sox leadoff man Adam Eaton stepped into the batter’s box to face Orioles right-hander Ubaldo Jiménez, nothing about it felt normal.

“I underestimated” how jarring it would be, Eaton, now the Nationals’ right fielder, told the Baltimore Sun. “When I first went into it, I didn’t think it would be a big deal. There was almost this half-asleep feel because there was no energy. There were no people there. … As baseball players, as teams, we feed off energy, and where there’s nothing there, it’s a very surreal and weird feeling that I’ll never forget, but I kind of wish I could.”

The Orioles pumped music over the loudspeakers between innings, and the public-address announcer recited the names of each batter before he stepped into the box — if only to maintain the normal rhythms of a game — but otherwise the stadium was free of manufactured sounds: No trumpet-call “Charge!” No scoreboard exhortations to “Make some noise!”

Palmer, who called the game for MASN alongside play-by-play man Gary Thorne, recalled being able to hear every word coming from the booth next door, where Ken “Hawk” Harrelson and Steve Stone did the visitors’ broadcast.

“It was surreal,” Palmer said. “People [later] told me they could hear my voice in the dugout. Normally we have to talk over the crowd. It’s in our headphones. But that day you could hear everything.”

When Orioles first baseman Chris Davis hit a three-run homer in the first inning — the decisive blow in the Orioles’ 8-2 victory, played in a crisp 2 hours 3 minutes — Harrelson called it in typically understated fashion on the White Sox telecast, saying, “Get foul. . . . It won’t.”

But alongside Harrelson’s voice, loud as day, was Thorne’s voice from the next booth over, rising to a crescendo as Harrelson’s trailed off. “Goodbye!” Thorne said. “Home run!”

Jesse Dougherty in West Palm Beach, Fla. contributed to this report.