CHICAGO (CBS) — Chicago Public Schools will lift the mask mandate for all students and staff next week, shifting to a mask optional plan beginning March 14, a move the Chicago Teachers Union called a “clear violation” of the district’s COVID-19 safety agreement with the union, which requires masks in schools through late August.

CPS officials cited declining COVID-19 numbers and increasing vaccination rates in the district as the reason for making masks optional effective next week.

CPS was one of the first to require universal masking in schools, and we would not be moving to a mask- optional model unless the data and our public health experts indicated that it is safe for our school communities,” CPS CEO Pedro Martinez said in a statement. “We will support our staff and students as we enter this new phase in the pandemic and continue to move forward together.”

“Chicago is at low risk for COVID-19 by every metric, including the historic and current metrics from the Centers for Disease Control and Prevention,” CPS officials said in a statement. “The city’s case counts and positivity are the lowest they have been since July 2021 and continue to fall.”

The Chicago Teachers Union said the district’s unilateral decision to lift the mask mandate “is a clear violation” of a COVID-19 safety agreement CPS negotiated with the union in January, after a heated dispute over the return to classrooms from remote learning led to teachers walking out and the district cancelling five days of classes. That COVID-19 safety agreement between CPS and CTU required masks for all students, teachers, and staff through Aug. 26.

“Our union will immediately be filing an unfair labor practice (ULP) charge against the district in response, and requesting that CPS bargain over this decision — a decision that impacts nearly 400,000 students, educators and school staffers in Chicago,” the union said in a statement.

CPS said it will continue to encourage everyone to wear masks in schools, especially those with lower vaccination rates, but will also support those who choose not to wear a mask and, “will provide tools that teachers and parents can use to guide conversations with students about the importance of honoring and respecting everyone’s personal choice.”

“The adults in our school communities will set the tone during this transition,” said CPS Chief Education Officer Bogdana Chkoumbova. “I am confident that we will continue to support and respect one another through this next phase of the pandemic. Family and community situations may change and dictate if a student or staff member wears a mask and we all need to ensure that everyone feels welcome to continue the practice that makes them feel safest and most comfortable.”

The union said, while it’s fortunate that COVID-19 cases, hospitalizations, and deaths are low in Chicago, vaccination rates remain low at many schools, especially those in communities with largely Black and Latino populations on the South and West sides.

“Students of color and their communities are particularly vulnerable as only 25 percent of all CPS schools have more than half of students fully vaccinated. Pre-kindergarten students, who are not yet eligible to receive COVID-19 vaccines, are also particularly vulnerable,” the union said.

The union also accused Lightfoot of caving in to attorney Thomas Devore, who has filed multiple lawsuits challenging various COVID-19 mitigations put in place by Gov. JB Pritzker and others, and is running as a Republican for Illinois attorney general. While most of those lawsuits have failed, a downstate judge last month halted enforcement of Gov. JB Pritzker’s school mask mandate at nearly 170 school districts across the state, issuing a temporary restraining order Devore had sought. While Pritzker later lifted the statewide school mask mandate, and the Illinois Supreme Court vacated the restraining order in that case, Devore is now asking the same downstate judge who ruled in his favor to block the CPS mask mandate that is currently in effect.

“Today’s move by Mayor Lightfoot and CPS not only violates the Union’s agreement with the district, it ignores the impact that COVID-19 has on communities of color. The mayor has instead prioritized the wishes of Tom Devore — an opportunistic, right-wing extremist hundreds of miles away from Chicago — over the wishes of the people of our city. She has prioritized the needs of Mt. Greenwood over the needs of Englewood, Roseland, Little Village, North Lawndale and Brighton Park,” CTU officials wrote in a press release. “Chicago Public Schools has gone from mayoral control to Devore control, as the downstate swindler calls the shots, the mayor capitulates and CPS falls in line.”

The union is calling on CPS to provide additional accommodations to students and staff to allow for remote options for those who are medically vulnerable. They also want CPS to provide a specific plan for distributing masks to all schools for students and staff who want them; to provide guidance and training to staff and parents “to ensure that no one is stigmatized for continuing to wear a mask,” to come up with a plan to protect students under age 5 who aren’t yet eligible to be vaccinated, to provide specific metrics for when masks will be required again if there’s another surge in cases, to track the impact of going mask optional, and to provide time for staff to conduct phone banking to encourage students to get tested and vaccinated.