# Does silica fume carry carbon from the silicon smelter that made it?

Canonical: https://senseible.earth/answers/silica-fume-carbon-allocation-concrete

Silica fume is collected from the off gas of silicon and ferrosilicon furnaces. Many methods treat it as a residue that carries only its collection, densifying and transport emissions; others allocate part of the smelter's burden. State which rule you used.

## Options

- Residue: only bagging, densifying and freight.
- By product: a share of smelter emissions by mass or value.
- Whichever you pick, apply it every year.

## Why it matters

Silica fume replaces some cement, so the rule decides how much credit a low carbon concrete mix can claim.

## What Senseible does here

Senseible reads bills, fuel invoices and production records into dated, fingerprinted records, so the figure you send a buyer can be traced to its documents.

- [Fly ash carbon allocation](https://senseible.earth/answers/fly-ash-from-power-plant-carbon-allocation)
- [Silicon metal and CBAM](https://senseible.earth/answers/is-silicon-metal-covered-by-cbam)

Sources: [GHG Protocol Corporate Value Chain (Scope 3) Standard](https://ghgprotocol.org/corporate-value-chain-scope-3-standard), [GHG Protocol Corporate Standard](https://ghgprotocol.org/corporate-standard)

Last reviewed 2026-10-22.