Environmental impact of shipping engines can be higher on a port-specific basis. Ultra-low sulfur diesel (ULSD) is a standard for defining diesel fuel with substantially lowered sulfur contents. As of 2006, almost all of the petroleum-based diesel fuel available in Europe and North America is of a ULSD type. In 2016 the IMO has made new sulfur regulations which must be implemented by larger ships by 2020. Of total global air emissions, shipping accounts for 18 to 30 percent of the nitrogen oxide and 9 percent of the sulphur oxides. Sulfur in the air creates acid rain which damages crops and buildings. When inhaled,
Environmental standard that can be released into atmosphere in order to maintain air quality and human health and regulate the release of greenhouse gases such as carbon dioxide (CO), oxides of nitrogen and oxides of sulfur. The standards are established in two phases to stay up to date, with final projections aiming to collectively save Americans $1.7 trillion in fuel costs and reduce the amount of greenhouse gas emissions (GHG) by 6 billion metric tons. Similar to the ambient standards, individuals states may also tighten regulations. For example, California set their own emissions standards through the California Air Resources Board (CARB), and