Warning signs of carbon monoxide poisoning include headaches, rapid breathing and heartbeat, fainting, and confusion. Once people show symptoms it's important to:

• Remove the person to fresh air
• Loosen tight clothing
• Administer CPR if needed
• Call 911 or the local rescue squad
• Give oxygen if available
• Evacuate the building
• Call the fire department to test CO levels
• Don't allow anyone to reenter the building until CO levels are safe.

(Source: Maine Department of Labor)