Studying what would happen if there's a limit on who could drive to work in Denver The Colorado Department of Public Health and Environment is studying a limit on who drives to workplaces on the Front Range because of air quality Author: Marshall Zelinger Updated: 8:14 PM MDT April 7, 2021 DENVER — For those of us working at home, getting fully vaccinated is the next step to normal. Then, it is returning to work. In person. Except, the Colorado Department of Public Health and Environment (CDPHE) is studying a way to limit who drives to work. The Employee Traffic Reduction Program has nothing to do with COVID-19 or traffic.