NEW YORK CITY - Ventilation inspection teams began Tuesday the task of inspecting 1,700 New York City public schools to make sure classrooms are safe to reopen by September, officials said.

"This is what it takes to guarantee our schools are safe," de Blasio said. "That's the effort that's going on right now." 

About 100 teams, of about two to four engineers each, will inspect ventilation systems, windows and fans in 1,700 public schools in the eight days between Tuesday and Sept. 1, CEO Lorraine Grillo said. 

Classrooms with locked windows will see them opened, classrooms without windows will get improved airflow, Grillo said. 

"The goal here is to have air flowing through these classrooms," Grillo said. "We're doing everything we can to make sure these buildings are safe."

Classrooms deemed unfit will either see issues addressed or the spaces taken offline and results will be posted online by Sept. 4, Chancellor Richard Carranza said. 

"We're taking a united approach," Carranza said.  

When faced with a question about ventilation during colder months, de Blasio argued global warming meant there would be more days this winter when teachers could open classroom windows. 

His ventilation announcement comes one day after de Blasio announced the DOE would support outdoor learning, an announcement that frustrated those who've been advocating for it all summer. 

"It's not new," de Blasio said Tuesday. "It's not mysterious to school leaders to think about this option." 

Carranza noted 243 schools submitted outdoor learning plans since Monday's announcement, but added he has not yet viewed the plans.  

"Our approach is to flatten the bureaucracy," Carranza said. "I'm just very excited." 

The mayor said indoor restaurant dining remained infeasible for New York City because eating inside remains, according to Senior Health Advisor Dr. Jay Varma, "a high risk activity."

Yet when reporters raised concerns about the spread of COVID-19 during lunch hours, when students will be eating at their desks and presumably talking loudly among each other, the mayor laughed.

Said de Blasio, "That sounds pretty good to me."