Study: Cleaner fuel, lower speeds cut pollution

   California’s clean fuel regulations and voluntary slowdowns by shipping companies have substantially reduced air pollution caused by commercial cargo ships near the state’s shore, according to a study published online Monday in Environmental Science & Technology.
    The study, led by the National Oceanic and Atmospheric Administration (NOAA), examined a containership operating under a 2009 California regulation requiring that ships switch to low-sulfur fuels as they approach the California coast, and also adhering to a voluntary state slowdown policy. The research team found that emissions of several health-damaging pollutants, including sulfur dioxide and particulate matter, dropped by as much as 90 percent.
    “Findings of this study could have national and global significance, as new international regulations by the International Maritime Organization require vessels to switch to lower-sulfur fuel near U.S. and international coasts beginning in 2012,” the California Air Resources Board (CARB), the state’s air regulatory agency, said in a statement. “The research team found reductions in emissions even where none were expected, meaning even greater reductions in air pollution, and associated respiratory health effects in humans, than regulators originally estimated.”
    In May 2010, a NOAA research aircraft flew over a commercial containership, Maersk Line’s Margrethe Maersk, about 40 miles off the coast of California. Researchers on the aircraft used sophisticated custom instruments to “sniff” the ship’s emissions before the ship switched to lower-sulfur fuels (by law, within 24 miles of the California Coast) and slowed down voluntarily. A few days later, scientists aboard the NOAA-sponsored Woods Hole Oceanographic Institute’s research vessel Atlantis sampled emissions of the same ship as it cruised slowly within the low-sulfur regulated zone.
    Sulfur dioxide levels, which were expected to drop, fell 91 percent, from 49 grams of emissions per kilogram of fuel to 4.3 grams. Sulfur dioxide is best known as a precursor to acid rain, but can degrade air quality in other ways, directly and indirectly through chemical reactions in the atmosphere. In particular, emissions of sulfur dioxide lead to formation of particulate matter in the atmosphere.
    Particulate matter pollution, regulated because it can damage people’s lungs and hearts, dropped 90 percent, from 3.77 grams of emissions per kg of fuel to 0.39 grams. Unexpectedly, black carbon levels also dropped by 41 percent, the team reported. Black carbon comprises dark-colored particles that can warm the atmosphere and also degrade air quality.
    “It’s important to know that the imposed regulations have the expected impacts,” said Daniel Lack, a chemist with NOAA’s Earth System Research Laboratory and the Cooperative Institute for Research in Environmental Sciences. “The regulators want to know, the shipping companies want to know, and so do the people.”
    In 2009, the U.S. Environmental Protection Agency and its Canadian equivalent, Environment Canada, estimated that shifting to low-sulfur fuels near coasts could save as many as 8,300 lives per year in those two countries, and ease the acute respiratory symptoms faced by another 3 million. But that 2009 assessment did not include the observed drops in several pollutant categories that Lack and his colleagues found, so the authors suggest the impacts could be greater.
    “These scientific findings clearly demonstrate that ships off our coast now emit significantly less sulfur pollution than in the past,” said CARB Chairman Mary Nichols.
    The new paper, Impact of Fuel Quality Regulation and Speed Reductions on Shipping Emissions: Implications for Climate and Air Quality, is available here.
    The project was funded by NOAA and CARB and conducted in close collaboration with the Maersk Line.