When America first reported an alarming wave of coronavirus cases this year, police departments across the country swiftly raised alarm about a lack of masks and other equipment that would protect officers as they went about their essential jobs.

“We just don’t have enough,” a spokesman for the Chicago Police Department complained in March about a shortage of personal protective equipment for officers.

But in Chicago as well as in other cities across the nation, police officers have been seen doing their jobs in recent weeks without masks, even in places where officials have mandated they wear them and even in situations such as crowded protests over racial injustice and police abuse, in which social distancing is nearly impossible. Sightings of officers without masks have come amid an uptick of virus cases in the South and the West in the weeks since many areas began reopening.

It is a worrisome development, according to medical experts, who warn that such moves increase the risk of infections both for officers and the residents they are charged with protecting. It is a puzzling turn, too, for people like Early Walker, an Illinois resident who was so moved by pleas from the police for personal protective equipment that he helped pay for hundreds of masks — handmade, with filters and customized with the Chicago Police Department logo. He handed them out to police officers in April, along with hot meals of chicken and mashed potatoes, at a funeral for Marco DiFranco, the first Chicago officer known to die of complications from COVID-19.

“They weren’t free,” Walker said, speaking of his donations. “I would think they would wear them, you know, especially considering the seriousness of this disease. One of the reasons I partook in buying them was because one of their fellow officers lost his life.”

Since tens of thousands of people began pouring into the streets to protest the death of George Floyd last month, images of lines of barefaced officers in Chicago, Seattle, Phoenix, New York City and elsewhere have circulated on social media.

In recent days, police officers without masks have been spotted on regular patrols and at protests in cities where policies require masks and where broader social distancing rules are still in place. During several protests in Phoenix, dozens of officers patrolled the streets as protesters marched. While a vast majority of protesters wore masks, almost none of the officers — a mix of city officers and state troopers — did so. In California, several sheriff’s departments have said they would not comply with the governor’s new rules requiring masks when social distancing was not possible.

Some protesters complained that officers who opted not to wear masks were endangering residents — another piece of a pattern that had sent people to protest police conduct in the first place.

“I do feel like it’s hypocritical,” said Mitchell Brooks, 30, a web developer in Raleigh, North Carolina, who said he had been at several demonstrations where most officers were not wearing masks while most protesters were. “Just trying not to risk being a disease vector is a pretty straightforward and easy way to mitigate any hardship you might do to your community and to protect it.”

Police officers and representatives for departments defended the actions of officers. They described a fast-moving situation in recent months that began with urgent concerns about the virus but quickly turned to contending with large protests over the death of Floyd and others.

In San Jose, California, some officers were not wearing virus protection gear in the first days of protests despite a policy requiring them to wear masks, gloves and glasses during interactions with the public. They needed to put on gas masks to keep safe while deploying tear gas, said Lt. Todd Trayer, a police spokesman, noting that both types of masks cannot be effective if worn simultaneously.

“Those were a super volatile couple of days,” Trayer said, adding that no officers have been disciplined for not wearing a mask.

“It’s such new ground, the combination of a protest and a pandemic,” he said. “I’ve never heard of that, and I’ve been here 25 years. I think they did a great job at what we needed to do at that very moment when everything was happening. But we can do better.”

Beyond the protests, officers have been spotted without masks in the course of regular police work.

About two weeks ago, Marie Mott said a dozen officers who responded to people fighting in the street in her neighborhood in Chattanooga, Tennessee, were barefaced when they hopped out of their vehicles and did not put on masks as they questioned people.

Mott, who has helped organize several protests over Floyd’s death, said she had spotted only a handful of officers with masks at marches and relatively few wearing masks since the coronavirus outbreak began.

Chattanooga does not have a written policy for police use of personal protective equipment “due to the fluid and often changing directives coming from the CDC and other levels of government,” Elisa Myzal, a police spokeswoman, said in an email.

“They have been instructed to wear PPE at all times when dealing with the public so long as it is feasible,” she said.

Myzal said that at protests, “a mask can greatly inhibit the clarity and volume of verbal commands. Standing on the front lines of a protest is not the time or place for confusion.”

When fears about the coronavirus began increasing in the United States — long before the nation convulsed in protests over police conduct — many police departments scrambled to obtain protective equipment.

In Chicago, donations of masks and gloves began to pour into the Police Department from the community, one longtime Chicago police lieutenant said.

Officers were exceedingly concerned then about the spread of the virus, a worry that grew in the weeks that came after as dozens of officers across the country were found to have or died of COVID-19. In Chicago alone, more than 500 police employees tested positive for the virus, with most recovering and able to return to work. Officers there took care, according to the lieutenant, who asked not to be named because he did not have authorization from police officials to speak with the news media. The police wiped down patrol cars between shifts and each vehicle was stocked with hand sanitizer and wipes.

Then on the last weekend in May, hundreds of officers were ordered into buses to be deployed to respond to protests over Floyd’s death.

At that point, worries about the virus became secondary, the lieutenant said. Officers were so busy handling protests, he said, that virus concerns were pushed aside in the moment.

In the days since, the spread of the virus in the city of Chicago has slowed, and many officers have abandoned their masks, the lieutenant said.

Thomas Ahern, a spokesman for the Chicago Police Department, said officers were required, and continuously reminded, to wear masks and gloves.

“Given the heightened activity that officers have been responding to in the past weeks, there may be situations in which officers may not have masks and gloves on,” he said.

Walker, the man who donated masks to the department, said he had been moved to help the police because he works with officers frequently through the towing company he owns, which relies heavily on police contracts. He helped buy masks for suburban police departments, as well as Chicago police officers, and estimates that he handed out about 10,000 masks in all.

After the death of Floyd, Walker said he felt compelled to protest and always wears a mask when doing so. He organized a march this month, “I Have a Black Son,” a demonstration through the Mount Greenwood neighborhood, an area where many police officers live and one with a history of racial tension. Most of the hundreds of people who marched wore masks, he said. Police officers on duty generally did not, he said, but they mainly kept at a distance from the marchers.

Still, Walker said he was concerned about both the officers and the protesters.

“I feel like at the end of the day, it’s everyone’s personal responsibility to be worried about their own personal health,” he said.