EDMONTON -- Students in Grades 4 to 12 will be required to wear masks in common areas and on school buses when they return to class in September under new guidelines from the provincial government.

Education Minister Adriana LaGrange and Chief Medical Officer of Health Dr. Deena Hinshaw announced the new requirements on Tuesday.

Hinshaw said the new recommendation is the result of the detailed review of the latest medical evidence.

"We know that masks can be an effective addition to reducing COVID-19 transmission when used properly," she said. "I believe that requiring masks in all staff and in all children Grades 4 and above is essential to limiting the spread within schools and protecting the health of all involved."

For students in kindergarten to Grade 3, mask use will be optional. 

"This is because mask use for younger children is a challenge due to difficulties with proper fit and compliance," LaGrange said. "Additionally, current medical evidence indicates that children under 10  may be less likely than older children or adults to transmit COVID-19."

The province has said repeatedly that it will not mandate the use of masks in public spaces but strongly recommends their use when a two-metre distance cannot be maintained.

Each student, teacher and staff member in the province will be given two reusable face masks.

Staff will also be given one face shield each to be used at their discretion. Single-use masks, hand sanitizer and contactless thermometers will also be provided by the province.

According to LaGrange, the province is spending $10 million on the new supplies, in addition to the $120 million funding increase that was previously announced. 

The Opposition NDP is calling for more changes to the plan, including a cap of 15 students per class and hiring more education and cleaning staff. Limiting parent and visitor admission to schools has also been suggested. 

The Alberta Teachers' Association said it welcomed the government's comittment, but echoed the NDP's criticsm and what it called a lack of consultation with educators. 

"The revised plan still falls far short of the expectations that have consistently been articulated by the Association in its representations," a statement reads. 

"Today’s announcement again does not adequately address the issue of distancing in Alberta’s overcrowded classrooms. The suggestion that masks need not be worn if students can be appropriately distanced within the classroom or if teachers are not working closely with students betrays a fundamental failure to understand what actually goes on in classrooms."

Alberta schools were closed in March. The government announced in July that school will reopen in the fall for full-time classes.

The decision prompted concerns from parents and teachers about how it can be done safely.

School boards were given guidelines for how to reopen during the pandemic, including staggering start times, having student cohorts, and having regular cleaning, screening and sanitization. None of the guidelines are mandatory.

Students with symptoms of COVID-19 will be required to get tested and only be allowed back into class after a negative result, according to Alberta's chief medical officer of health.

Some school boards have said they will offer families the option to continue schooling at home. Each board will have its own plan.

As of July 31, Alberta has recorded 10,843 cases of COVID-19 and 196 deaths.