Public Law, Chapter 162(LD 550):
All single-family dwellings and multi-apartment buildings sold in the state and newly constructed single-family dwellings must have at least one CO detector in an area within or giving access to a bedroom. (Effective date: October 31, 2009)

LD 623

Existing lodging establishments, dormitories and care facilities must have CO detectors. (Effective January 2016)