A net search for Euro 0/1/2 finds:

European Union emission regulations for new light duty vehicles (cars and
light commercial vehicles) are specified in the Directive 70/220/EEC. This
basis Directive was amended a number of times, some of the most important
amendments including:

 a.. Euro 1 standards (also known as EC 93): Directives 91/441/EEC
(passenger cars only) or 93/59/EEC (passenger cars and light trucks)
 b.. Euro 2 standards (EC 96): Directives 94/12/EC or 96/69/EC
 c.. Euro 3/4 standards (2000/2005): Directive 98/69/EC, further amendments
in 2002/80/EC
 d.. Euro 5 standards (2008): Proposed regulation [COM(2005) 683] published
in December 2005
Fuels. The 2000/2005 standards were accompanied by an introduction of more
stringent fuel regulations that require minimum diesel cetane number of 51
(year 2000), maximum diesel sulfur content of 350 ppm in 2000 and 50 ppm in
2005, and maximum petrol (gasoline) sulfur content of 150 ppm in 2000 and 50
ppm in 2005. "Sulfur-free" diesel and gasoline fuels (? 10 ppm S) must be
available from 2005, and become mandatory from 2009.

Emission Testing. Emissions are tested over the ECE 15 + EUDC / NEDC chassis
dynamometer procedure. Effective year 2000 (Euro 3), that test procedure was
modified to eliminate the 40 s engine warm-up period before the beginning of
emission sampling. This modified cold start test is referred to as the New
European Driving Cycle (NEDC) or as the MVEG-B test. All emissions are
expressed in g/km.

For PM measurements, particle number limits have been considered at the Euro
5 level, in addition to the existing mass-based limits (NEDC). The draft
Euro 5 proposal indicates that number-based PM limits should be implemented
once the measurement methods are established, following the completion of
the UN/ECE Particulate Measurement Programme (PMP). At the time of the
publication of the Euro 5 proposal, its mass-based PM emission limits could
only be met by closed particulate filters. Number-based PM limits would
prevent the possibility that in the future open filters are developed that
meet the PM mass limit but enable a high number of ultra fine particles to
pass.

Once the PMP work is completed, changes may be also introduced to the PM
mass measurement procedure, which may require adjusting the proposed Euro 5
PM mass emission limit.