Fig. 1: Schematic diagram of the four sources of emissions that apply directly to both upstream and downstream petrochemical production.
From: Reducing uncertainties in greenhouse gas emissions from chemical production

Upstream products are used as input materials both for other types of upstream product and for downstream products as depicted by the black arrows. A collapsed version of this diagram is used as a key for other figures. See Supplementary Section 1.1 for product aggregation into groups.