contingent-workers-contractors

Are we able to ask contingent workers (Contractors) for personal email and phone numbers for emergency contact purposes? We’re working with Security on a emergency response system that sends out notifications to employees. We were discussing gathering personal phone and email from these workers as well so in the event there was an emergency and we needed to contact folks, they would also be notified. For example if there was a burst pipe at HQ and we sent out a notification to all employees but not the contingent workers, it would be a bit awkward for our employees to leave but the contingent workers to be left behind.