Dave Mayer arrived outside Nationals Park on Tuesday morning, bringing the total number of major league ballparks the retired anesthesiologist and die-hard Chicago Cubs fan has visited this year to 13. No matter that the 67-year-old, nor any other spectator, would be allowed inside the stadium for the Washington Nationals’ game against the Toronto Blue Jays that night.

Mayer, the executive director of the MedStar Health Institute for Quality and Safety and the CEO of the Patient Safety Movement Foundation, a nonprofit dedicated to eliminating preventable medical harm, is in the midst of a walk and drive across America to raise awareness for patient and caregiver safety. He’s covered more than 1,100 miles on foot over the last six months and hopes to complete his tour of all 30 MLB parks by the start of spring training in 2021.

“If I was 25, maybe I’d say, ‘Oh, I’ll just do this next year,’” Mayer said Tuesday. “But I don’t know how long my knees and hips will hold out. I also just felt like there was an urgency. This pandemic has exposed gaps in our system that I think many people have been warning about. We could’ve done better, we should’ve done better.”

In February, inspired in part by a re-watching of the Oscar-nominated film “Forrest Gump,” Mayer resolved to walk from Miller Park in Milwaukee to Wrigley Field in Chicago to shine a light on preventable medical harm, which one 2016 study claimed is the third-leading cause of death in the United States behind heart disease and cancer.

Mayer, who has Cubs season tickets, planned to bookend his week-long trip by seeing his favorite team play in both cities. He had started taking long walks near his home in Arizona to build his endurance for the roughly 100-mile trek from Milwaukee to Chicago when the novel coronavirus pandemic postponed the baseball season and prompted Mayer to alter his plans.

“I felt helpless,” Mayer said. “I wanted to do something for my friends and colleagues on the front lines, who I knew were going through some very challenging times.”

On May 22, the day he was originally scheduled to be in Milwaukee, Mayer began a 10-day, 128-mile walk to all 10 Cactus League spring training ballparks and Chase Field, the regular season home of the Arizona Diamondbacks. With his wife Cathy’s blessing, he then set a goal to visit all 30 major league ballparks while completing a “virtual” walk across America. He started his quest, which he has been documenting on Twitter and Instagram, on the drive with Cathy from Arizona to their apartment in Columbia, Md.

The couple stopped in Colorado, where Mayer walked 20 miles from Red Rocks Park and Amphiteatre to Coors Field, home of the Rockies. He then visited Kansas City and St. Louis and walked from Milwaukee to Chicago, albeit without the excitement of a baseball game at either end of the journey. On Sunday, after previous stops in Detroit, Cleveland and Pittsburgh, Mayer completed a two-day, 19-mile walk from the MedStar Health corporate office in Columbia to Oriole Park at Camden Yards.

Mayer has walked at least five miles for more than 170 consecutive days and said he’s often joined by at least a dozen people, including colleagues, family and friends. He dedicates most of his walks to individuals who have lost their lives due to preventable medical harm and leaves painted stones inscribed with their names along the way.

Tuesday’s walk to Nationals Park began at Arlington National Cemetery, where Mayer held a brief ceremony to honor the lives of all of the patients and caregivers lost due to medical errors every year.

“This walk was really special to me, being from this area now,” said Mayer, who walked past the White House, Capitol building and Freedom Plaza en route to the Navy Yard. “Today it was really for everybody.”

Tuesday wasn’t Mayer’s first visit to Nationals Park, as he makes it a point to attend at least a couple games whenever the Cubs are in town. He snapped a photo of a banner of Nationals Manager Dave Martinez outside the ballpark and had nothing but praise for the former Cubs bench coach, who helped Chicago end its 108-year World Series title drought in 2016.

“When he got the lead job here in Washington, I told friends, ‘You watch, the guy will bring a championship to your city,’” said Mayer, who has the date and time — 12:46 a.m. Eastern time — that the Cubs clinched their most recent World Series tattooed on his right ankle. “When the team got off to a rough start last year, I told my friends, ‘Trust him, let him ride out this year. I’ve seen what the guy can do.’ I was happy they won last year, especially for him.”

Mayer plans to drive to Atlanta on Wednesday and complete a walk to the Braves’ Truist Park. From there, he will meet his daughter and her fiance in Tampa Bay, and check Tropicana Field off his list. His next stop was supposed to be Marlins Park, but with coronavirus cases surging in South Florida, he said he will return to Maryland instead and visit Miami at a later date.

In his more than 20 years advocating for patient and caregiver safety, giving PowerPoint presentations and lectures at symposiums and conferences across the country, Mayer said he’s seldom been as encouraged by the response to an awareness campaign as he has been in the past few months. He also acknowledged his work is far from done.

“I don’t know how much time I have left on this planet,” he said, “but I’m going to keep walking until people start noticing this issue."

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