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Modeling the Effects of Outdoor Use of Gasoline Powered Generators on Indoor Carbon Monoxide Levels



Liangzhu Wang, Steven Emmerich


Background The U.S. Centers for Disease Control and Prevention (CDC) has reported that half of non-fatal CO poisoning incidents during the hurricane season in 2005 involved generators operated outdoors but within seven feet of the home. The guidance provided on the safe operating distance of a generator is often neither specific nor consistent. Furthermore, some generator manufacturers recommend the use of extension cords to be "as short as possible, preferably less than 15 feet long, to prevent voltage drop and possible overheating of wires". However, the use of short extension cords may result in placement of the generator too close to avoid the home to reduce the likelihood of the entry of CO. Methods Multiple scenarios of a portable generator operated outdoors were modeled using the CONTAM indoor air quality model with a computational fluid dynamics (CFD) model to predict CO concentrations near and within a home. The simulation cases included both human-controllable factors (e.g., the generator location and exhaust direction and window opening size) and non-controllable factors (e.g., wind, temperature, and house dimensions). During a simulation run, CFD predicted a distribution of CO levels at the house surface. Through a link of CFD and CONTAM, the surface CO levels were provided as inputs for predictions of transient CO profiles in different rooms of the house. Results For the house modeled in this study, a generator positioned 5 m away from open windows may not be far enough away to limit CO entry into the house. A perpendicular wind to the open window brought more CO infiltration than wind with an angle. Lower wind speed generally caused more CO entry when indoor to outdoor temperature difference is relatively small. When the buoyancy effect was significant, CO infiltration was determined by the combination of wind and buoyancy effects. To reduce CO entry, the generator should ideally be positioned outside of airflow recirculation region near the open windows. Implications Significant CO entry into a house may occur when a portable generator is operated inside the airflow recirculation zone near the house.
Proceedings Title
2009 National Environmental Public Health Conference
Conference Dates
October 26-28, 2009
Conference Location
Atlanta, GA, US


computational fluid dynamics, simulation, indoor air quality, health, carbon monoxide


Wang, L. and Emmerich, S. (2009), Modeling the Effects of Outdoor Use of Gasoline Powered Generators on Indoor Carbon Monoxide Levels, 2009 National Environmental Public Health Conference, Atlanta, GA, US, [online], (Accessed May 25, 2024)


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Created October 25, 2009, Updated October 12, 2021