The Pearl River Delta (PRD) is a region with a single airshed, but different administrative and legal practices for controlling air quality. Under the Regional Cooperation Plan on Building a Quality Living Area (QLA Plan) released in June 2012 the Governments of Hong Kong, Guangdong and Macau have outlined a strategy to collaborate in reducing emissions from vessels throughout the PRD. This report provides evidence designed to assist policymakers in the region with this objective. It focuses on regulating toxic exhaust emissions from ocean-going vessels (OGVs) -- the most significant contributors of marine emissions. The findings show that marine sources of sulphur dioxide (SO2) emissions currently account for 519 premature deaths per annum in the PRD. These deaths could be reduced by 91% should an Emission Control Area (ECA) mandating the use of fuels with lower sulphur content be introduced. The report also demonstrates that three less comprehensive control measures would also reduce OGV emissions and associated public health impacts by 41-62%. Policymakers are encouraged to introduce these measures as stepping-stones on the way to establishment of an ECA for the PRD.