What does this NUMBER mean?

All personnel working on the Gordie Howe International Bridge project site(s) must participate in an orientation facilitated by Bridging North America which includes training focused on safety, quality, environment, security and human resources. The number refers to the number of workers, including project staff, technical specialists and employees of subcontractors and suppliers, who have already participated in orientation sessions for the Canadian side of the project. Approximately 150 of these workers are directly employed by Bridging North America.