New York EMS workers aren’t alone. Nationwide, fire departments received 23.5 million medical calls in 2018, over twice as many as the 9.2 million they received in 1994, Castillo’s first year on the job. Over the same period, the number of fire calls fell by a third from 2 million to 1.3 million, according to the National Fire Protection Association. This leaves emergency medical workers like Castillo playing a much larger part in the day-to-day operation of fire departments.

But despite the growing burden on EMS personnel, the median earnings for EMTs or paramedics in the United States is $34,000 per year — which is a third less than firefighters’ average annual pay of $50,000, and a little more than half of police officers’ $63,000, according to 2018 figures from the Bureau of Labor Statistics.

“I’ve always been a third-class citizen in the 911 response service,” Castillo said.

In New York, Local 2507, the union that represents Castillo and other EMTs, is demanding pay parity with other first responders by holding protests and filing a lawsuit against the city for pay discrimination. Many EMS workers, a category which includes both EMTs and paramedics, say their low pay reflects a lack of appreciation for their work, which can be just as dangerous as and at times even more dangerous than the work of police officers and firefighters.

“EMS is a much more dangerous occupation than previously recognized,” said Brian J. Maguire, a former New York City paramedic-turned-academic who has conducted peer-reviewed studies on EMS job hazards in the U.S. and Australia. Maguire says his work indicates the average EMS worker is just as likely as a firefighter or a police officer to be killed on the job, and more likely to be injured, a claim he supports by work like his 2017 study of EMS-related violence published in the American Journal of Public Health.

But Maguire, as well as EMS personnel themselves, says this risk isn’t always recognized by the politicians who set EMS workers’ wages, including in New York City, where firefighters, police officers and sanitation workers make significantly more than EMS workers. Police and firefighters who have been with their departments for five and a half years earn a base salary of $85,000 and sanitation workers with the same amount of time on the job earn $77,000. By comparison, base pay for even the most experienced EMTs and paramedics maxes out at $48,000 and $61,000, respectively.

In January 2019, during contract negotiations between EMS unions and the city of New York, Mayor Bill de Blasio addressed criticisms of the pay gap between EMS workers and other first responders by saying the work is not comparable.

“We are trying to make sure people are treated fairly and paid fairly, but I do think the work is different,” he said. De Blasio administration spokesperson Laura Feyer told NBC News that the city’s EMTs are paid better than their private sector counterparts, and said that raising EMS pay and benefits to equal those of firefighters would cost the city $450 million per year.

In September, New York EMS workers rallied in front of City Hall to demand pay parity. Among the speakers were New York state Attorney General Letitia James, as well as the City Council speaker and 2021 mayoral hopeful, Corey Johnson. James and Johnson pointed to gender and racial discrimination as potential contributors to the pay gap.

“They may not look the same — FDNY is majority white and male, while EMS is predominantly made up of women and minorities — but they’re alike in one critical way: They are heroes,” James said, according to the Queens Gazette. Johnson called the pay gap a “social justice issue,” contrasting himself with the mayor he hopes to replace.

Oren Barzilay, the president of Local 2507, says his union has filed a lawsuit against the city for pay discrimination, pointing out that New York EMS workers are far more diverse than firefighters. “We strongly believe that gender and race has something to do with the wages,” he told NBC News, adding that EMTs are “penalized harsher” for on-the-job infractions than other first responders. “Firefighters, police officers, sanitation: they all have an honorable job and they deserve what they make. All these jobs are high risk, and it’s time the city recognizes EMS jobs -- they’re also dangerous.”

Since EMS workers often respond to dangerous calls alongside police officers and firefighters, the pay disparity can feel especially galling.

“One of my buddies can retire right now. He’s a cop,” Castillo said. “I’ve put in four more years than he has, and my pension doesn’t match his.”

Priced out of New York City, Castillo and his family now live in New Jersey. He says the “vast majority” of his co-workers do 10 to 20 hours of overtime each week in order to make ends meet. “You start missing baseball games and stuff like that, it gets tough.”

Carl Gandolfo, who worked as a paramedic in Brooklyn but recently transferred and became an instructor at the city’s training academy, says he saw his workload significantly increase during his nine years on the job.

“We would get three or four calls in an eight-hour shift,” Gandolfo, 44, said of his early days as a paramedic. But by the time he transferred, he was racing to respond to an average of six dispatches per shift. This higher workload could be a contributing factor to an increase in medical emergency response times — which have increased by around 10 percent between 2012 and 2017 in New York City, according to the most recently available government data.

Gandolfo is a paramedic, which is a higher paid position than an EMT. Paramedics undergo more extensive training that typically takes one or two years, compared to EMT training, which typically takes less than six months.

But like Castillo, Gandolfo also was priced out of his hometown. “Obviously we couldn’t afford to buy a home [in New York City] on our own. Just to save up for a down payment would’ve taken 10 years,” he said. Gandolfo moved his family to Long Island, where he took a second job and combined households with his parents in order to buy a house.

No matter how much they’re paid, EMS workers like Castillo say their work will be even more important as the country’s baby boomers age.

“Hopefully you never need us,” he said. “But it’s the insurance against the worst.”