2 At the September 26, 1997, Diplomatic Conference, many Member States expressed concern that these NOx limits would not result in the emissions reductions they were intended to achieve. The Member States, through the MEPC, had set out in the early 1990s to achieve a 30 percent reduction in NOx emissions from these engines. However, newly available test data suggested that NOx levels from marine diesel engines were already at or close to the agreed-upon standards. Several delegations were concerned about this shortfall, and expressed the desire to provide for a review of these emission limits with the aim of proscribing more stringent limits, taking into account the adverse effects of such emissions on the environment and any technological developments in marine engines. Through Conference Resolution 3, also adopted on September 27, 1997, the Parties invited the MEPC to review the NOx emission limits at a minimum of five-year intervals after entry into force of the 1997 Protocol and, if appropriate, amend the NOx limits to reflect more stringent controls.
3 While the Annex has not yet gone into force, it is believed that owners of ships that operate internationally will begin to comply with the Regulation 13 NOx limits beginning 1 January 2000. This is because ships that operate internationally will be required to demonstrate compliance with Regulation 13 when their owners seek to obtain an International Air Pollution Prevention Certificate after entry into force. Owners of ships that do not operate internationally may be exempted from the Regulation 13 NOx emission limit requirements prior to entry into force of the 1997 Protocol if the relevant Administration allows such exclusion pursuant to Regulation 13(1)(c).
4 Because of continuing concern about the contribution of marine diesel engines to both local and international air quality, the United States submits the following information and related recommendations for consideration by the Committee.
Health and environmental effects associated with NOx emissions
5 NOx emissions from marine diesel engines are of concern to the international community primarily due to their contribution to ground level ozone. Ground level ozone is formed when hydrocarbons and oxides of nitrogen react in the presence of sunlight. Over the past few decades, many researchers have investigated the health effects associated with both short-term (one- to three-hour) and prolonged acute (six- to eight-hour) exposures to ozone. Numerous controlled-exposure studies of moderately exercising human subjects, as well as field and epidemiological studies, provide evidence of associations between short-term and prolonged acute ozone exposures and health effects ranging from respiratory symptoms and lung function decrements to increased hospital admissions for respiratory causes. In addition to these health effects, daily mortality studies have suggested a possible association between ambient ozone levels and an increased risk of premature death.
6 In addition to human health effects, ozone is known to adversely affect the environment in many ways. These effects include reduced yield for commodity crops, for fruits and vegetables, and commercial forests; ecosystem and vegetation effects in such areas as National Parks; damage to urban grass, flowers, shrubs, and trees; reduced yield in tree seedlings and non-commercial forests; increased susceptibility of plants to pests; materials damage; and reduced visibility. Nitrogen oxides (NOx), key precursors to ozone, also result in nitrogen deposition into sensitive nitrogen-saturated coastal estuaries and ecosystems, causing increased growth of algae and other plants.
