School districts now have a new tool to decide how to open safely for students, teachers and the community.

Pennsylvania's top health and education officials have created the COVID-19 Early Warning Monitoring System Dashboard that rates all 62 counties in the state in three tiers: low, moderate and substantial.

The tiers are based off of two criteria: new COVID-19 case incidence rate per 100,000 residents (based on seven-day average) and percent positivity rates per diagnostic testing.

The criteria combine to give a transmission rate for the counties.

Counties may move from one tier to another depending on the COVID-19 data. School districts have struggled over the last few weeks with coming up with safe and equitable reopening plans. There are hundreds of districts in Pennsylvania. Here is a map with reopening plans for all of the districts in southeastern Pennsylvania.

Health Secretary Dr. Rachel Levine and Education Secretary Pedro Ramos said the rating system is set up to be used as recommendations, not a mandate for school reopenings.

"These are just that, recommendations," Levine said.

Forty-one of the state's 62 counties are listed in the low transmission rate tier, 25 counties are in the moderate transmission rate tier and one county is in the substantial tier. Union County in northcentral Pennsylvania is the only county in the substantial tier.

Full in-person schooling is possible for the counties in the low tier, Levine and Ramos said. Blended schooling, described as a hybrid mix of in-person and virtual learning, is possible for schools in the moderate tier. All-virtual schooling is recommended for districts in the substantial tier.

Here is how the state determines the tiers:

• LOW: Incidence rates per 100,000 residents of less than 10 AND positivity test rates of less than 5%
• MODERATE: Incidence rates per 100,000 residents of less than 100 OR positivity test rates between 5% and 10%
• SUBSTANTIAL: Incidence rates per 100,000 residents of more than 100 OR positivity test rates of more than 10%

The president of one of Pennsylvania's largest teachers' unions urged all districts to follow the new state tiers in reopening schools next month.

"I strongly encourage all schools in Pennsylvania to follow them," Pennsylvania State Education Association President Rich Askey said. "Doing so will ensure that Pennsylvania's students, staff and families stay safe, that we slow the spread of the virus and that we know schools will be safe places to learn and work when the virus is under control."

How School Districts Across the Philadelphia Region Are Reopening

Hundreds of school districts in Philadelphia, Montgomery, Delaware, and Chester counties along with South Jersey and Delaware are scrambling to come up with plans for the 2020-2021 school year. We have a map with answers for parents and teachers.

Public School Districts' Reopening Plans in the Philadelphia Region

Hundreds of school districts across southeastern Pennsylvania, southern New Jersey and Delaware are scrambling to prepare for the new school year starting in September amid the COVID-19 pandemic. Here are plans for each district. This map is still being updated.

Data: NCES, School Districts
Credit: Sara Smith, Brian X. McCrone, Elizabeth Both, Nina Lin/NBC 10 Philadelphia