Steam methane reforming (SMR) using natural gas is the most commonly used technology for hydrogen production. Industrial hydrogen production contributes to pollutant emissions, which may differ from the theoretical estimates due to process conditions, type and state of installed pollution control equipment. The aim of this study was to estimate the impacts of hydrogen production using facility-level real emissions data collected from multiple US EPA databases. The study applied the ReCiPe2016 impact assessment method and considered 12 midpoint and 14 endpoint impacts for 33 US SMR hydrogen production facilities. Global warming impacts were mostly driven by CO2 emissions and contributed to 94.6% of the endpoint impacts on human health, while global warming impact on terrestrial ecosystems contributed to 98.3% of the total endpoint impacts on ecosystems. The impacts estimated by direct emissions from the 33 facilities were 9.35 kg CO2e/kg H2which increased to 11.2 kg CO2e/kg H2when the full life cycle of hydrogen production including upstream emissions was included. The average global warming impact could be reduced by 5.9% and 11.1% with increases in hydrogen production efficiency by 5% and 10%, respectively. Potential impact reductions are also found when natural gas hydrogen production feedstock is replaced by renewable sources, with the greatest reduction of 78.1% found in hydrogen production via biomass gasification, followed by 68.2% reduction in landfill gas and 53.7% reduction in biomethane-derived hydrogen production.