Life-cycle assessment
Impact Category
A class of environmental issue — such as climate change, acidification, or eutrophication — into which life-cycle inventory flows are grouped and characterised in LCA.
Definition
An impact category is a defined class representing an environmental issue of concern, used in life-cycle impact assessment to translate inventory data (emissions and resource use) into indicator results. Midpoint categories such as global warming potential (measured in CO₂-equivalents), acidification (SO₂-equivalents), and eutrophication model cause-effect chains partway; endpoint categories aggregate these into areas of protection such as human health, ecosystem quality, and resource availability.
References
definition and typology
Overview
What it means
Impact categories are the vocabulary that makes LCA results legible: hundreds of different emissions become a handful of comparable environmental issues. Choices of categories, characterisation models, and midpoint-versus-endpoint levels shape results, which is why standards (ISO 14040/44) require them to be selected and justified transparently.
The same category logic underpins product environmental footprints and many ESG metrics.
How it is used
Used in LCA practice, product footprinting (EU PEF), EPD development, and corporate environmental accounting.
Why it matters
Without a shared category system, every environmental claim would measure something different; categories are the common units of environmental comparison.
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