Use of personal protective equipments would be the best bet, however if possible workers can be grouped to work in shifts thereby reducing overcrowding
Please check out our paper titled "Early Impacts of the COVID-19 Pandemic on the United States Construction. The paper includes some perspectives about the need for such a system. "Another important reason for slowing down ongoing projects was the increase in requests to reassess mechanical ventilation and air filtration systems. One of the architects mentioned that owners were now concerned with whether their mechanical ventilation and air filtration systems would adequately replace contaminated air with clean air"
The paper can be accessed and downloaded from the following links:
Article Early Impacts of the COVID-19 Pandemic on the United States ...