Editing Diesel fuel (section)

=== Environment hazards of sulfur ===

In the past, diesel fuel contained higher quantities of [[sulfur]]. [[European emission standards]] and preferential taxation have forced [[oil refinery|oil refineries]] to dramatically reduce the level of sulfur in diesel fuels. In the European Union, the sulfur content has dramatically reduced during the last 20 years. Automotive diesel fuel is covered in the European Union by standard [[EN 590]]. In the 1990s specifications allowed a content of 2000 ppm max of sulfur, reduced to a limit of 350 ppm by the beginning of the 21st century with the introduction of Euro 3 specifications. The limit was lowered with the introduction of Euro 4 by 2006 to 50 ppm ([[ULSD]], Ultra Low Sulfur Diesel). The standard for diesel fuel in force in Europe as of 2009 is the Euro 5, with a maximum content of 10 ppm.<ref>{{cite web|url=https://www.transportpolicy.net/standard/eu-fuels-diesel-and-gasoline/|title= EU: Fuels: Diesel and Gasoline|website=TransportPolicy.net|access-date=17 July 2020}}</ref>

{| class="wikitable"
! Emission standard
! At latest
! Sulfur content
! Cetane number
|-
| N/a
|align=right| 1 January 1994
|align=right| max. 2000 ppm
|align=right| min. 49
|-
| Euro 2
|align=right| 1 January 1996
|align=right| max. 500 ppm
|align=right| min. 49
|-
| Euro 3
|align=right| 1 January 2001
|align=right| max. 350 ppm
|align=right| min. 51
|-
| Euro 4
|align=right| 1 January 2006
|align=right| max. 50 ppm
|align=right| min. 51
|-
| Euro 5
|align=right| 1 January 2009
|align=right| max. 10 ppm
|align=right| min. 51
|-
|}

In the United States, more stringent emission standards have been adopted with the transition to  [[Ultra-low-sulfur diesel|ULSD]] starting in 2006, and becoming mandatory on June 1, 2010 (see also [[diesel exhaust]]).