One view reflects a nationwide reality: With limited supplies of virus-blocking N95 face masks, paramedics responding to 911 calls should limit their use to the most contagious of settings.

The other view, from paramedics told to use a less effective mask in the tight confines of an ambulance next to a coughing patient, is just as compelling.

And where these views collide — as seen in the operations of one large Maryland fire department — remains a daily source of tension for first responders battling the pandemic.

“We’re all kind of on the edge with this thing,” said TJ Brennan, a Montgomery County paramedic, firefighter and vice president of the firefighters union. “There is always a lot of risk associated with our jobs, like a building fire. But this is different. A building fire can’t come home with us and hurt our families.”

Mask choice led to a shouting match recently inside a Rockville fire station, according to Brennan, another union official and a paramedic involved in the exchange. The paramedic disobeyed orders from a direct supervisor telling him to avoid wearing an N95 mask unless he was performing what the county designated “high-risk” respiratory procedures, the three said. The April 19 dust-up was resolved after another commander arrived at the station and heard the paramedic out, according to the three.

“For once, I got the impression that someone from our leadership understands that he is dealing with a tinder box waiting to ignite due to the level of stress and anxiety in the air right now,” the paramedic later wrote in his journal, adding that he intended to continue wearing the more secure masks on all coronavirus ambulance runs: “You can take that to the bank.”

County officials for Maryland’s most populous jurisdiction say their masking policies are designed to balance the safety of front-line workers and the need to keep a supply of the limited masks. Montgomery County has distributed masks not just to firefighters, but also to nursing homes, long-term-care facilities, social workers, police officers and correctional officers.

“We believe that we’ve laid out the best procedures for our department,” said Division Fire Chief Charles Bailey, who has helped lead the coronavirus response for the department.

Bailey said exceptions to N95 protocol are allowed if the users can explain why. “The decision has to be deliberate, defensible and communicated,” he said. “We don’t want them to be frozen by policies.”

By one indicator, the service has weathered the crisis relatively well: Eighteen of its more than 2,000 front-line workers and trainees have tested positive for the novel coronavirus, and none has died. Montgomery County officials acknowledge they don’t know how many of the department’s active-duty firefighters have been tested for the virus.

Firefighters and paramedics have received tests at urgent-care centers or through their personal physicians. On Thursday, county officials announced a new testing program, which initially will target firefighters, police officers and correctional officers as well as nursing home and long-term-care facility staff and residents.

N95 masks are so named because they filter out about 95 percent of micron-level, airborne particles. When carefully fitted and sized, the devices provide a barrier unmatched by loose­fitting surgical or cloth masks.

“They’re the gold standard,” Bailey said.

At the same time, given worldwide shortages of N95 masks for much of this year, county leaders have felt compelled to limit N95 use by medics — a rate that stands at 80 to 100 a day. Such rationing has taken place with as many as 60 calls a day to suspected coronavirus patients, involving up to a half-dozen paramedics and firefighters getting close to patients.

Montgomery also leads the state in covid-19 deaths. More than 531 of its residents have died, and approximately 10,291 have caught the virus. Montgomery coronavirus patients who have called 911 over the past two months have had contact with approximately 1,020 paramedics and firefighters — or more than three-quarters of the county’s career paramedics and firefighters, according to county data.

Bailey said that by issuing protection guidance beyond the use of N95 masks, fire officials have kept the infection rate among their front-line workers relatively low.

During 911 calls, suspected coronavirus patients are asked to meet first responders outside if possible. The medics arrive wearing surgical masks, eye protection and gloves — staying at least six feet away as they begin asking questions. They place surgical masks on the patients when practical.

Any of a series of symptoms reported by patients, including fever, cough, shortness of breath, colds, nausea, diarrhea and loss of taste or smell, dictate that medics step into a protective gown.

Even then, and even in the back of a cramped ambulance, medics are to hold off on upgrading to an N95 mask unless they perform high-risk, aerosol-producing procedures, such as administering oxygen, suctioning fluids and squeeze-bag resuscitation.

Despite the rationing, county officials saw their reserve supply of 3M-branded N95 masks — fit-tested, reserved for firefighters and ready to use — drop from 10,000 to 1,440 over the past two months.

County officials in recent weeks have greatly replenished their supply of N95 masks — with a delivery several days ago bringing their total inventory close to 2 million, said Earl Stoddard, the county’s emergency management director.

But that stockpile, he said, is reserved for a range of workers — from those at nursing homes, assisted-care facilities and physicians’ offices to police officers, correctional officers and paramedics. As the masks are used, Stoddard said, he wants to replenish the stockpile to maintain at least 2 million — especially as Montgomery County opens back up this summer and faces the lingering threat of a sudden rise in cases this fall. Stoddard said the inventory also serves as a backup for county hospitals.

Fire officials say their allotment of new N95 masks, which still must be fit-tested for their front-line workers, will give them enough masks to last well into the summer. They indicated they have no plans to change the rules for when they are to be worn.

In late January, as the threat of the coronavirus surfaced and Stoddard sought to bring in more N95 masks, the worldwide shortage became acutely clear.

“It’s not for lack of money,” he said several weeks later. “We can’t buy it.”

By mid-April, Montgomery’s Fire and Rescue Service had about 4,200 fit-tested N95 masks on hand, according to figures kept by Stoddard. The agency had an additional 15,000 N95 masks on hand, but they were a different brand that had not been fit-tested for use. And officials wanted to keep much of the N95 stock in case they were overwhelmed by a rise in cases.

“We’re just trying to protect the supply as long as possible,” Stoddard said.

Montgomery fire officials established their N95 mask procedures, in part, by following guidance from the Centers for Disease Control and Prevention.

On March 10, recognizing worldwide shortages of the masks, the CDC changed its recommendations on face protection for first-responders. Surgical masks, the CDC said, were now “an acceptable alternative” for general paramedic practices aside from those “likely to generate respiratory aerosols.” Using another term for N95 mask, “respirators,” the CDC wrote: “When the supply chain is restored, fit-tested EMS clinicians should return to use of respirators for patients with known or suspected covid-19.”

The move was panned by first-responders, who said an agency charged with issuing critical medical recommendations was being guided by nonmedical equipment shortages. They noted that the CDC’s website describes a wide gap between surgical masks and N95s: “Most surgical masks do not effectively filter small particles from the air and do not prevent leakage around the edge of the mask when the user inhales.”

“The supply chain should not dictate the recommendation for a lower level of protection,” Harold Schaitberger, general president of the International Association of Fire Fighters, wrote in a March 11 letter to U.S. Health and Human Services Secretary Alex Azar. “In our uncontrolled environment, a tight-sealed face mask such as the N95 or higher is necessary to fully protect our members.”

Out in the field, a paramedic working in a Rockville station, who spoke with The Washington Post on the condition of anonymity to candidly describe his mask-wearing decisions, said he begins all medical calls by following county protocol: wearing a surgical mask, eye protection and gloves.

That affords him protection to ask patients about their symptoms, particularly when he can do so from six feet away. But when he must get close to a patient suspected of having covid-19, especially one who is coughing and especially when he boards an ambulance with them, he dons an N95 mask.

“We’re sitting in a 6-foot-by-6-foot box with someone. If they’re a suspected covid-19 patient, I’m putting on an N95,” he said.

He did so the morning of April 19 — riding to the hospital with a coughing, elderly woman who had a fever. Back at his fire station, he said, a commanding officer questioned his use of the mask and ordered him to restrict his use of N95s to department policies.

“I’m sorry,” the paramedic remembers telling him, “but I’m not going to follow that order.”

Things went south, he acknowledges.

“I lost my cool,” he wrote in his journal. “This started a screaming match.”

After other commanders got involved, he said, the altercation faded away without formal disciplinary action.

The paramedic said he knows the county has had reason to conserve N95 masks.

But for weeks, he and his brethren have asked commanders to loosen the restrictions — especially now with the county finally able to get its hands on reserve supplies.

“I can see all aspects of this. I get it. I really do,” said Capt. Brock Cline, another official with the union. “But for years, we’ve been taught and empowered to make decisions in the field. Now guys in ambulances are being asked over the radio what kinds of masks they’re wearing.”