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Simulation of Residential CO Exposures from Portable Generators with and without CO Hazard Mitigation Systems Meeting Requirements of Voluntary Standards, Revision 1



Steven Emmerich, Brian Polidoro, Matthew Hnatov, Janet Buyer, Matthew Brookman


This report documents work performed by the U.S. National Institute of Standards and Technology (NIST) and the U.S. Consumer Product Safety Commission (CPSC or Commission) under an interagency agreement in support of the Commission's effort to address the carbon monoxide (CO) poisoning hazard associated with consumer use of portable generators. This report documents the plan, developed by NIST and CPSC staff, for a computer simulation study performed by NIST and provides examples of the study results. CPSC staff will use the study's results to evaluate the effectiveness of CO hazard mitigation requirements that were adopted in two voluntary standards in 2018. These two ANSI-approved standards are ANSI/PGMA G300-2018, Safety and Performance of Portable Generators (referred to as PGMA G300) and UL 2201, Standard for Carbon Monoxide (CO) Emission Rate of Portable Generators, Second Edition (referred to as UL 2201). Both voluntary standards have requirements for a system that will shut the generator off when specific CO concentrations are present near the generator. PGMA G300 also has other requirements, including a notification to the user after the generator has shut off, while UL 2201 has a reduced CO emission rate requirement. The methodology of the simulation study was largely similar to that used by CPSC staff to evaluate the benefits of the proposed rule issued by the Commission in 2016 to address the hazard of CO poisoning from portable generators. This simulation study used the same forty buildings, weather conditions, and generator characteristics to study the rate at which the CO emitted from the generator accumulates in, transports within, and leaves the homes and detached garages for generators with and without the CO mitigation requirements prescribed in the voluntary standards. The plan involved performing approximately 140,000 simulations using NIST's indoor air quality modeling program CONTAM. This report presents the simulation plan and detailed CO and COHb simulation results for sample scenarios from two of the houses and one of the detached garages. Note: At the request of CPSC staff, NIST staff performed additional simulations using a 15 % longer run time for UL 2201 generators in a subset of the house models. These simulations are documented with sample results in new Appendix D of this report.
Technical Note (NIST TN) - 2202r1
Report Number


Generator, carbon monoxide, carboxyhemoglobin, CONTAM, exposure, indoor air quality, measurements, multizone airflow model, safety, simulation


Emmerich, S. , Polidoro, B. , Hnatov, M. , Buyer, J. and Brookman, M. (2022), Simulation of Residential CO Exposures from Portable Generators with and without CO Hazard Mitigation Systems Meeting Requirements of Voluntary Standards, Revision 1, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online],, (Accessed June 14, 2024)


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Created December 28, 2022