Carbon monoxide (CO) is a toxic, odorless, colorless gas produced by incomplete fuel combustion in furnaces, water heaters, and gas appliances. Even small concentrations damage health by binding to hemoglobin and reducing oxygen transport to vital organs. HVAC systems must operate safely without producing or allowing CO accumulation in occupied spaces.
Health Effects and Exposure Limits
OSHA limits occupational CO exposure to 50 ppm over 8 hours. Exposure to 1200 ppm causes severe headache and dizziness within 1 hour. Concentrations of 6400 ppm cause death within 1 hour. Symptoms include headache, fatigue, nausea, and confusion, often mimicking flu.
Prevention and Detection
Proper HVAC installation ensures combustion byproducts vent outside through sealed flue pipes. Annual furnace inspections detect cracked heat exchangers and blocked vents preventing CO leakage. Battery-powered CO detectors at $30 to $100 alert occupants to dangerous levels above 35 ppm, meeting UL 2034 safety standards. Building codes require CO detectors in homes with fuel-burning appliances.