Annex 42 Complementary information to source category 5b 2-Stroke Engines
Overview of recent revisions
No revisions to emission factors in this source category have been made. Additional guidance has been introduced on classifying sources within this category, estimating activity rates, and on data quality aspects.
Derivation of emission factors
Release to Air
Different emissions occur during different phases like start-up and engine warming. Since 2-stroke engines are mostly used for smaller engines, catalytic converters are hardly ever used. The annual average mileage, type and level of maintenance of vehicles are different for different countries. In many cases, small engines are not very well maintained. This may result in higher emissions of PCDD/PCDF. Unfortunately, no data is available which relates the age and level of maintenance to the level of PCDD/PCDF emissions. All data used for deriving emission factors are based on various European studies.