Under California Assembly Bill 685, employers who receive “notice of potential exposure” to COVID-19 of an employee who was physically at the worksite must, within one business day, notify all employees who were also present with the affected employee during the window of potential infection. The notice must be in writing and delivered in the way the employer typically communicates with workers, but it cannot include any personally identifiable employee information.  In addition to potentially exposed employees, the employer must also notify the employers of any subcontracted employees, and any union representative, and must comply with additional technical notice requirements or face costly civil penalties.  If three or more employees test positive, that is considered an “outbreak” and additional notice requirements must be met.