In a recent letter to the Environmental Protection Agency (EPA), the Passenger Vessel Association (PVA) said that more understanding is needed before an efficient and effective process to reduce marine emissions can be finalized. Responding to the agency’s Notice of Proposed Rule Making (NPRM) EPA-HQ-OAR-2003-0190, Control of Emissions of Air Pollution from Locomotive Engines and Marine Compression-Ignition Engines Less Than 30 Liters per Cylinder, PVA president, Jonathon Claughton, noted that the diversity of the U.S. passenger vessel industry makes it very different from the towboat and railroad industries. Describing that diversity, Mr. Claughton explained that many of the vessels in the 6,000-plus U. S. Coast Guard-inspected passenger fleet operate only in the hundreds of hours per year. For example, many vessels are used for seasonal excursions and thus have a minimal impact on the environment. In its comments, PVA called on EPA to reconsider the deadlines for compliance, especially for the still-to-be-developed, Tier 4 marine engines which will be based on land technologies that have not yet been shown to be adaptable to the marine environment. PVA also suggested that any possible requirement calling for existing marine engines to be altered for better emissions performance when they are “remanufactured” be the subject of a separate rulemaking to allow more time for coordination between government and industry. Further, PVA asked EPA to perform a cost/benefit analysis to ensure that reducing emissions of sulfur and nitrogen oxide from marine engines will not result in increased fuel consumption, carbon emissions, or have other unintended outcomes. PVA stated that proposed Tier 4 Emission Technology presents problems for both existing and new high speed ferry and passenger vessels. For example, Mr. Claughton noted the challenge to vessels operating outside the U.S. where the ultra low sulfur fuel and urea required by the proposed technology may not be available. Likewise, the heavy on-board equipment called for by EPA would likely have a negative impact on existing and planned vessels tightly designed for speed and performance.