After the mother missed the deadline to sign up for remote schooling, she begged her son’s pediatrician to sign a letter exempting the 5-year-old from the Philadelphia School District’s mask mandate.

The child had mild asthma, and she thought a mask would make it worse. She also thought he was too young to comply with the all-day rule.

Daniel Taylor, director of community pediatrics and child advocacy at St. Christopher’s Hospital for Children, patiently explained why he couldn’t provide an exemption: A mask would not affect the child’s asthma and since asthma could worsen COVID-19, masking was particularly important for him. Teachers were being trained to help kids wear face coverings properly. And the best thing the mother could do to protect her son and herself would be to get vaccinated.

“She was swayed somewhat that masking is important if the child has asthma. Not so much swayed about trusting the teachers,” Taylor said as he recalled the encounter, one of dozens of exemption requests in the past month his group has fielded. “And not swayed at all about the science behind the vaccine.”

For pediatricians and family physicians, school mask mandates are the latest headache and heartache, dragging them into a debate fraught with scientific, political, educational, public health, and personal arguments.

It can be a minefield for hospitals, too.

“If one doctor says yes and one says no, that’s not a good place to be in,” said Douglas Thompson, chief medical officer at St. Chris, which serves a predominantly low-income population in North Philadelphia.

St. Chris does not have a blanket policy on granting mask exemptions, leaving the decision to individual practitioners, Thompson said. But around the country, a deluge of requests has led some providers to be preemptive.

Nemours Children’s Health, a pediatric health system in Delaware, New Jersey, and Pennsylvania, has sent emails to parents and posted a statement on its website: “The American Academy of Pediatrics (AAP) recommends all students older than 2 years and all school staff should wear face masks at school unless medical or developmental conditions prohibit use. Therefore, we do not provide mask exemption letters for school.”

In North Carolina, where COVID-19 is surging even though 63% of adults are fully vaccinated, Hendersonville Pediatrics sent an email to families saying its physicians “will not write a mask exemption letter for any patient under any circumstance.”

In Minnesota, a large group of pediatric lung specialists balked at exemption requests for kids playing indoor sports. “The providers and nurses at Children’s Respiratory and Critical Care Specialists will not provide mask exemption letters,” they wrote, noting that special masks for hockey players have been developed to improve airflow and reduce condensation.

While wearing a mask for hours on end may be unpleasant, it does not cause physical or psychological harm, contrary to opponents’ misinformation on social media.

There are certain conditions that make masking impractical or intolerable for a small minority of children age 2 or older. Based on guidance from the AAP and the Centers for Disease Control and Prevention, children who have a physical or intellectual disability that makes them unable to remove a cloth mask should not be required to wear one. But children with speaking problems, autism, or a mental health disorder should not be automatically exempted. Parents and teachers should consider options such as face masks with clear plastic inserts, or providing remote instruction for the child.

Heart and pulmonary conditions, including asthma, do not automatically warrant a medical exemption, experts agree, especially since those conditions put people at high risk for COVID-19 complications.

But like vaccinations, masking is seen by some as a matter of personal choice, not a matter of protecting their own health and that of others. Fierce opposition to school mask rules is playing out in various ways, with health providers often caught in the middle.

Pennsylvania, for example, ordered masking for students, staff and visitors as of Sept. 7 in all K-12 schools and childcare facilities. But some school boards, including in the Eastern Lancaster County School District, allowed parents to exempt their children with nothing more than a signature — no need for a doctor to attest to a medical condition or disability.

In a Sept. 10 letter to all 500 school districts, the Pennsylvania Education Department said parental sign-off isn’t enough; medical documentation from a physician must be provided. But it’s not clear how far state officials will go to enforce the order.

Schools with lots of low-income students face a particularly thorny dilemma: Is it better to condone mask exemptions at the risk of a COVID-19 outbreak, or strictly enforce masking at the risk that some parents will opt for remote schooling? Studies have found that “learning loss” during remote instruction last year has worsened achievement gaps linked to socioeconomic disadvantages and race.

Taylor said he was surprised when a couple of schools near St. Chris sent a letter asking doctors to authorize exemption requests already signed by parents — in effect, putting the onus on doctors to ignore their own medical society’s guidance.

“It’s almost like, ‘We need our kids to come to school, so we’re going to cater to some parents,’ ” Taylor said. “I worry there are smaller practices out there that would just sign it.”

Of course, even doctors and nurses can oppose masks and vaccines. Joel Yeager, of Heritage Family Health in Lebanon County, denounced Pennsylvania Gov. Tom Wolf’s mask and shutdown orders early in the pandemic. This month, he posted online a four-page letter claiming masks cause health problems, citing two journal articles that have been retracted. He invited parents to “print your own copy” to seek a school mask exemption.

The Wolf administration said it would be referring doctors that promote such falsehoods “to the appropriate licensing boards for possible disciplinary action.”

Staff writer Sarah Gantz contributed to this article.