More than 500 carbon monoxide alarms have been donated to the Prince George’s County Fire/EMS Department, and hundreds more have been pledged in the wake of the poisoning deaths of five people last month in an Oxon Hill home that was filled with the odorless, colorless gas. Among the donors: Manufacturers Kidde and First Alert donated 200 carbon monoxide alarms each, and Pepco has pledged to give 200 along with the utility’s annual donation of 1,000 smoke detectors. These carbon monoxide alarms will be distributed to Prince Georgians who can’t afford to purchase them, said Prince George’s County fire spokesman Mark Brady.