The effects of marine vessel fuel sulfur regulations on ambient PM2.5 along the west coast of the U.S

This work uses PM2.5 data and Positive Matrix Factorization (PMF) modeling to explore the effects of two marine vessel fuel sulfur regulations along the west coast of the United States (US); California's (CA) Ocean-Going Vessel Clean Fuel Regulation (CA-CFR) implemented in July 2009 and the North American Emissions Control Area (NA-ECA) implemented in August 2012. Data from 31 chemically speciated PM2.5 monitors along the US west coast were analyzed and 9 sites with strong linear correlations between vanadium and nickel were selected for PMF modeling. The 9 sites were modeled independently and for 8 sites, 3 in CA and 5 in Washington State (WA), a well-defined factor linked to marine vessel residual fuel oil (RFO) combustion was identified. For these 8 sites, model results were subdivided into three time periods; a three year period prior to implementation of the CA-CFR, a three year period after the CA-CFR but prior to the NA-ECA, and a one year period after implementation of the NA-ECA. Marine vessel PM2.5 distributions were compared between the three time periods to determine if statistically significant reductions had occurred. Comparing marine vessel PM2.5 for the three years before and after CA-CFR implementation, all CA sites indicated statistically significant reductions, with reductions in annualized average marine vessel PM2.5 from 30 to 52% (0.09–0.78 μg/m3). Comparing marine vessel PM2.5 for the three years before NA-ECA implementation and the 1 year after, 2 of 5 WA sites indicated statistically significant reductions in annualized average impacts (45–50%, 0.12–0.23 μg/m3) and 1 of 3 sites in CA (46%, 0.04 μg/m3). These results demonstrate that marine vessel fuel sulfur regulations on the west coast of the US have been effective at reducing PM2.5 impacts from marine vessel RFO combustion at some locations, with the implementation of the CA-CFR showing more success than the NA-ECA. The greater observed success of the CA-CFR is, to some extent, probably the result of a longer 3-year implementation time compared to only 1 year for the NA-ECA. •Ambient effects from two marine vessel fuel sulfur regulations were investigated.•Ambient V and Ni data from 31 U.S. west coast sites was analyzed.•PM2.5 source apportionment was performed for 9 sites.•V + Ni mass and marine vessel PM2.5 reductions align with regulated areas.