ARLINGTON, Texas (CBSDFW.COM) – As schools consider resuming in-person classes, students and parents are reminded of the risks that come with the airborne transmission of COVID-19.

Melanie Sattler, a professor at the University of Texas at Arlington specializing in air pollution, says most particles of the virus people disperse are caught by masks, but there is a small amount that aren’t.

She said to keep students safe, schools need to take a closer look at their air filtration systems come fall.

“There is though a minority small fraction of droplets that researchers know, that can travel farther than the six feet, and be airborne,” Sattler said.

It’s recommended that schools and offices change or upgrade their ventilation practices to address that minority of smaller particles, she said.

High quality HVAC systems not only reduce the risk of spreading unwanted pathogens, but also breathe new air into the rooms.

Sattler said this, along with air changes, mitigate the spread.

“Make sure that you have enough air changes per hour and for schools under normal circumstances, the air changes per hour can range from six to 20. With COVID we want to try to increase that,” Sattler said.

Sattler also said that schools typically recirculate cooled or warmed air to save on energy costs, but she said that is not a safe option come fall. Instead, they should focus on bringing outdoor air in, when possible.

“The recommendation is to bring in as much outside air as the air handling system can take and still have people remain comfortable,” she said.

Another way schools can mitigate the spread, is to start the air handling system two hours before usual, to give the air more time to process.

She said these efforts in combination with wearing a mask and staying socially distant, should make students feel comfortable going back.

“The social distancing and the mask, are the main lines of defense, and they are very effective. So it’s really just a small fraction of the smaller droplets that may be of concern,” she said.