Carbon Monoxide detectors are now mandatory (2011 law) in rental homes in California, but it is not required unless the dwelling has an attached garage, fireplace, or gas appliances, and I’m not confident that a detector will work when installed on the ceiling, as many of the combination smoke/CO alarms are.
That’s interesting about the carbon filter, but makes sense- how can you eliminate a gas without venting it outdoors? I don’t have the science chops to know, but it sounds expensive and complicated.
