Ethylene complex, by-product propylene and C4 Users of this dataset should apply the provided environmental load allocation coefficients for proper assessment of the environmental impact. The coefficients for ethylene, propylene, and C4 are 0.54, 0.26, and 0.19, respectively. These reflect the distribution of environmental loads based on product mass and must be used to accurately assign burdens to the respective outputs. It is important to consider this allocation when calculating environmental performance metrics for propylene, bearing in mind that the functional unit for this data set is 1 tonne of propylene.