CHICAGO — Chicago Public Schools said classrooms are ready for students and teachers to safely return Wednesday after the district installed air purifiers and took other measures to prevent the spread of COVID-19.

Last month, the Chicago Teachers Union said neither teachers nor students should return to class because school buildings are old and not designed to sufficiently ventilate and purify air during a pandemic.

CPS said it addressed those concerns by spending $8.5 million to put a HEPA air purifier in every classroom. District officials said the 20,000 purifiers are capable of removing “99.9% of ultrafine particles,” including airborne mold, bacteria and viruses like COVID-19. 

Additionally, CPS officials said the district implemented the top five COVID-19 mitigation efforts recommended by the Centers for Disease Control to keep schools safe, and hired independent industrial hygienists to produce a school-by-school analysis of air quality and ventilation systems.

Now the district says classrooms are ready for students and staff so long as they have either a HEPA filter or an operating mechanical ventilation system which includes both an air supply and an exhaust. By those standards, CPS says 99% of its classrooms are ready and the ones that are not will be prioritized for repairs. 

Chicago Teachers’ Union Vice President Stacy Davis Gates expressed skepticism about the new measures Wednesday. 

“Quite frankly, we find it a little tough to believe that every single classroom in every single building is up to code,” Gates said. “What we understand is that this requires windows to be open in our classrooms… I don’t know about you, but Chicago winters are pretty brutal so i don’t know how many windows we can have open.”