Chicago, Mar 15 (IANS): Chicago Public Schools (CPS), the third largest school district in the US, lifted its mask mandate and introduced an optional policy.

But there were "certain situations" when students and staff members will still be required to wear a mask, including when visiting with the school nurse or other medical professionals in the school building; while exhibiting Covid-19 symptoms; and following an exposure to the virus, reports Xinhua news agency.

An entire class may also be required to wear masks, "at the direction of Chicago Department of Public Health", the Chicago Tribune said ina report on Monday.

In a letter to parents on March 11, CPS CEO Pedro Martinez reminded families that beginning Monday "all CPS schools will move to a mask-optional model".

"Far fewer people are getting sick, ending up in the hospital, and losing their lives to Covid-19," the newspaper quoted Martinez as saying.

"However we feel about masks, I think we can all agree that this is positive progress."

Martinez said CPS was one of the first major districts to require universal masking, and one of the last school districts to relax the mandate.

"We will continue to follow the science, and CPS may require masks again if community transmission reaches a moderate or high level."

The vast majority of schools in the state of Illinois ended masking requirements in February following Governor J.B. Pritzker's halting of the school mask mandate, as well as prompted by new federal guidance from the Centers for Disease Control and Prevention.

But CPS had continued its mask mandate due to an agreement they'd reached with the Chicago Teachers Union following five days of cancelled classes in January, after union members declined to teach in person due to safety concerns.

CPS families are divided on the newly introduced optional mask requirement.

Some disagreed with the decision out of safety concern, while others have applauded the easing of restrictions in light of the new federal guidance.