After an inspection, here are a few great tips you can provide to your homeowners.
To protect yourself from CO poisoning:
• Know the symptoms—Shortness of breath, nausea, dizziness, light-headedness or headaches. High levels of CO can be fatal, causing death within minutes.
• Install a CO alarm on every level of your home in a central location and outside each sleeping area.
• Purchase an alarm that has the label of a recognized testing lab and mount according to manufacturer’s instructions.
• Test CO alarms at least once a month and replace accordingly.
• If the alarm sounds, open a window or door, move outside to fresh air and call emergency personnel.

http://www.nfpa.org/assets/files//PDF/CarbonMonoxideFactSheet.pdf
For more carbon monoxide tips and education, visit www.nfpa.org.