Large ships, locomotives and aircraft are all considered “nonroad” vehicles or engines. Ocean-going ships, often referred to as Category 3 (C3) marine engines, are the largest ships on the water and include container ships, cruise ships, tankers and bulk carriers. These large, diesel-fueled vessels travel around the world and contribute significantly to air pollution in many of our nation’s cities and ports, as well as inland areas. Likewise, locomotive engines, which power trains that transport vast quantities of goods and also serve as a mode of transportation, run on diesel fuel and play a role in air pollution levels across the country. In many places, diesel emissions represent the greatest contribution to cancer risk from air pollution. Further, because diesel emissions are a complex mixture of chemicals, exposure to this pollution contributes to a wide range of non-cancer health risks, such as respiratory disease, cardiovascular effects, neurotoxicity, low birth weight in babies, premature births, congenital abnormalities and elevated infant mortality rates. Ships and locomotives also emit large quantities of particle pollution, or particulate matter (PM), which can aggravate respiratory conditions, such as asthma and chronic bronchitis and has been associated with irregular heartbeat, heart attacks and premature deaths. Those with diabetes, heart or lung disease, the elderly and children are at highest risk from exposure to PM. The nitrogen oxides (NOx) emissions from ships and locomotives transform into aerosol particulates and also combine with volatile organic compounds in the presence of sunlight to form ground-level ozone, also known as smog. High ozone levels cause serious respiratory problems, aggravated asthma, decreased lung function, inflammation of lung tissue and an increase in hospital admissions and emergency room visits for respiratory symptoms, and are also associated with premature death. Diesel pollution also contributes to regional haze, acid rain and global warming.
Meanwhile, the rapid growth in worldwide air travel has heightened concerns over the influence of aviation on air quality. Commercial aircraft engines emit nitrogen oxides (NOx) that contribute to the formation of ozone and particle pollution, as well as to acid rain and haze, and react with common organic chemicals to form a wide variety of toxic compounds. These aircraft also emit greenhouse gases (GHG) that cause global warming. Piston-engine aircraft, used for general aviation, are fueled with leaded aviation gasoline and are a significant source of lead emissions. Once taken into the body, lead circulates through the bloodstream and is accumulated in the bones; it can also have an impact on the capacity of blood to carry oxygen. The most common health impacts of lead are neurological effects in children and cardiovascular effects, such high blood pressure and heart disease, in adults. Infants and young children are particularly sensitive to even low levels of lead, which may contribute to behavioral problems, learning deficits and lowered IQ. Lead is persistent in the environment and accumulates in soils and sediments through deposition from air sources. Ecosystems near lead sources have suffered a range of adverse effects including losses in biodiversity, decreased growth and reproductive rates in plants and animals and neurological effects in vertebrates.
Ships, locomotives and aircraft have all been the subject of EPA regulation. With respect to aircraft, on July 1, 2015, EPA published in the Federal Register its Proposed Finding that Greenhouse Gas Emissions from Aircraft Cause or Contribute to Air Pollution that May Reasonably Be Anticipated to Endanger Public Health and Welfare and Advance Notice of Proposed Rulemaking. EPA will use the comments it receives on the Advance Notice of Proposed Rulemaking to inform its work with the International Civil Aviation Organizaton (ICAO), which is seeking to adopt an international CO2 emissions standard for aircraft in 2016, as well as to potentially use its authority under Secton 231 of the Clean Air Act to propose, adopt and implement the ICAO standard (or a more stringent standard, if warranted) domestically.
In 2010, EPA adopted standards that apply to C3 marine engines installed on U.S. vessels as well as to marine diesel fuel that is produced and distributed in the U.S. These standards are based the International Maritime Organization’s (IMO) 2008 adoption of two new tiers of NOx emission standards and fuel sulfur limits for C3 ships. The Tier II engine NOx emission standards took effect in 2011 and the Tier III standards will begin in 2016. The tightest of these emissions standards apply to ships operating in areas designated by the IMO as Emission Control Areas (ECA), where C3 marine vessels operating within 200 nautical miles of the coastline must use fuel that has no more than 10,000 parts per million sulfur, with a phase down to 1,000 parts per million sulfur in 2015. EPA’s 2010 action, which was approved by the IMO, created an ECA applicable to North American waters that took effect on August 15, 2012. This program will achieve significant reductions in NOx, SO2 and PM2.5. In April 2014, the IMO amended the implementation requirements of its Tier III NOx emission standards so that for any ECAs established in the future anywhere in the world, the Tier III NOx standards will apply only to ships built after the date on which the IMO adopts a country’s proposed designation of an ECA (or a later date, as determined by the country’s applying for an ECA designation).
For locomotives, EPA’s most recent regulatory action was in 2008, when it tightened emission standards for existing locomotives when they are “remanufactured” (i.e., refurbished), established near-term emission standards for newly built locomotives and set longer-term standards for newly built locomotives that reflect the application of high-efficiency technologies. EPA’s most recent action to control aviation emissions was in June 2012, when it adopted emission standards and related provisions for aircraft gas turban engines used on commercial passenger and freight aircraft. The requirements of this rule are referred to as the “Tier 6” and “Tier 8” standards and are ones already adopted by the International Civil Aviation Organization. With respect to piston-engine aircraft, EPA, in June 2012, announced its intention to study, over the next several years, the impacts of lead emissions from these aircraft to determine whether they may reasonably be anticipated to endanger public health and welfare. If the agency determines such endangerment exists, it will pursue regulatory action to set standards to reduce lead emissions; these standards will include ones related to the composition of piston-engine aircraft fuel to control lead emissions.