A North Texas school district is the first to use a new air-filtration system designed to kill the virus responsible for COVID-19. The system uses a unique air filter that heats to 200 degrees, which researchers say kills more than 99-percent of the virus. The Slidell ISD in Wise county has deployed it in all of its schools. Superintendent Taylor Williams says it’s an excellent supplement to their campus cleaning routines. The system is made by Medistar and developed in cooperation with researchers at the University of Houston. Company officials say they would use it at other school districts in Texas and Florida.