HILLSBOROUGH COUNTY, Fla. -- One of the biggest challenges facing school districts as they work to reopen is making sure buildings are properly ventilated.

Hillsborough County Public Schools announced it is investing in HVAC improvements to help with air flow and filtration in classrooms.

"One thing we want to is take pro-active steps as an organization," said Superintendent Addison Davis. "One thing we can't do is just copy and paste what we've always done related to our way of work."

Research indicates COVID-19 is largely transmitted through the air.

So the school district is upgrading air filters on all campuses to a MERV 13 rating.

MERV ratings measure the ability of an air filter to capture particles.

MERV 13 is recommended by the CDC if possible.

"It's a thicker filter. It's got a different structure in it that allows it to filter out different levels of particles," said Michael Grabham, Regional Vice-President of Energy & Technical Services with McKinstry.

"By installing MERV 13 filters, this district becomes the state leader in this arena," said Steve Gossett, Operating Partner at Community Infrastructure Partners.

In addition, every school in the district is being checked by engineers, making the necessary repairs and upgrades. They are also conducting an assessment of indoor air quality along with CO2 sensor accuracy and exhaust fan operations.

"It's super important that these filters get put in but it's also really important the other component of what we're doing which is checking the ventilation and air change so we're bringing in fresh air which has very little contaminants in it," said Grabham.

The upgrades don't come cheap. A spokesperson said the district will spend an additional $690,000 for the MERV 13 filters.

"But at the end of the day, you can't put a price tag on safety," said Davis.

District officials said they worked hard to get the MERV 13 filters because there's a national shortage.

"We worked every single day to go through every avenue to be able to gain access," Davis said.

Hillsborough County Schools is hoping to have the MERV 13 filters in half its schools by August 24 with filters in every school by October.

Installation will start first with schools that have units already that are the most compatible with the MERV 13 filters.

"Obviously we can't come in and build all new schools and new systems, so everything we can do currently we are doing to make sure we have the right indoor air quality," said Grabham.