The RTA does not address smoke and carbon monoxide alarms directly. It says that it is the landlord's responsibility to make sure that the property is kept in a good state of repair, is fit to live in and meets all the health and safety standards that apply.
Both the landlord and tenant have responsibilities when it comes to fire prevention. The landlord must make sure that smoke alarms and carbon monoxide alarms are installed and are working properly. Tenants must notify the landlord as soon as they become aware that a carbon monoxide or smoke alarm in their unit is not working and they must not remove the batteries or tamper with the alarms in any way.
More information on fire safety can be found on the website of the Office of the Fire Marshal.