City inspectors will launch a herculean effort to examine the ventilation in every New York City classroom in just one week to ensure they’re safe for the start of school in September, Mayor de Blasio said Tuesday.

“School ventilation action teams” comprised of engineers and ventilation experts will comb through every classroom in the city’s more than 1,600 public schools starting today, and ending by Sept. 1, Hizzoner said.

“We’re marshaling the resource of not only the Department of Education and School Construction Authority, but other agencies as well coming together to make sure that every school is ready, that the ventilation systems are working,” de Blasio said at a Tuesday press conference.

Inspectors will check whether windows in city classrooms can open to allow in fresh air, and whether fans to pull in and expel air in school buildings are working. A Daily News analysis of building inspections from 2019 found roughly 650 of 1,500 school buildings had at least one deficiency in its exhaust fan system.

The teams will report back to the Education Department, which will post the results online by Sept. 4, said Schools Chancellor Richard Carranza.

Depending on the results of the inspection, Education Department officials will either give the room the go-ahead, make upgrades before the planned start of school on Sept. 10, or take the rooms out of commission for in-person learning, Carranza added.

“All students or staff will be teaching or learning in safe spaces with proper ventilation. That is our promise to you,” Carranza said.