Field Measurements of Small Marine Craft Gaseous Emission Factors during NEAQS 2004 and TexAQS 2006

Exhaust emission factors were calculated for a number (n = 116) of small marine craft encountered during the 2004 New England Air Quality Study-International Transport and Chemical Transformation and 2006 Texas Air Quality Study 11 field campaigns. Emission factors are reported for NOx, SO2, and CO in units of grams of pollutant per kilogram of fuel. These factors are compared to emission factors derived from the U.S. Environmental Protection Agency (EPA) NONROAD model, separated into spark-ignition and compression-ignition sources. NO, emission factors observed were significantly and substantially higher than predicted by the model by a factor of 2-10. CO emission factors were not significantly different than the model outputs. Because of the correlation between exhaust hydrocarbon and CO for marine craft it is expected that EPA estimates of hydrocarbon exhaust emission factors are not significantly in error, Small commercial marine craft (e.g., inshore fishing trawlers) are not part of NONROAD, but their measured emission factors were comparable to those of large diesel recreational marine craft in the model.