these rules, EPA estimates that over 239,000 tons of particulate matter will be reduced annually. Outside of the US diesel oxidation catalysts are often available and DPFs will become available as ULSD is more widely commercialized. Another technology for reducing black carbon emissions from diesel engines is to shift fuels to compressed natural gas. In New Delhi, India, the supreme court ordered shift to compressed natural gas for all public transport vehicles, including buses, taxis, and rickshaws, resulted in a climate benefit, "largely because of the dramatic reduction of black carbon emissions from the diesel bus engines." Overall, the fuel switch for the vehicles reduced black carbon emissions enough to produce a 10 percent net reduction in CO2-eq., and perhaps as much as 30 percent. The main gains were from diesel bus engines whose CO2-eq. emissions were reduced 20 percent. According to a study examining these emissions reductions, "there is a significant potential for emissions reductions through the [UNFCCC] Clean Development for such fuel switching projects." Technologies are also in development to reduce some of the 133,000 metric tons of particulate matter emitted each year from ships. Ocean vessels use diesel engines, and particulate filters similar to those in use for land vehicles are now being tested on them. As with current particulate filters these too would require the ships to use ULSD, but if comparable emissions reductions are attainable, up to 120,000 metric tons of particulate emissions could be eliminated each year from international shipping. That is, if particulate filters could be shown reduce black carbon emissions 90 percent from ships as they do for land vehicles, 120,000 metric tons of today's 133,000 metric tons of emissions would be prevented. Other efforts can reduce the amount of black carbon emissions from ships simply by decreasing the amount of fuel the ships use. By traveling at slower speeds or by using shore side electricity when at port instead of running the ship's diesel engines for electric power, ships can save fuel and reduce emissions. Reynolds and Kandlikar estimate that the shift to compressed natural gas for public transport in New Delhi ordered by the Supreme Court reduced climate emissions by 10 to 30%. Ramanathan estimates that "providing alternative energy-efficient and smoke-free cookers and introducing transferring technology for reducing soot emissions from coal combustion in small industries could have major impacts on the radiative forcing due to soot." Specifically, the impact