Replacement of sulphur hexafluoride by nitrogen in sport shoes

Number

197-EN

Section

General Section

Use

Sector

Manufacture of textiles, leather, fur
Manufacture of rubber products
Manufacture of plastics products, including compounding and conversion

Function

Filler

Process

Other

Product category

other

Application

Sport shoe production

Abstract

A popular sportswear company used sulphur hexafluoride to fill air cushions in the shoe soles. After realizing the substance has a high potential to contribute to the climate change, they tried alternatives and end-up using nitrogen.

Substituted substances

Sulfur hexafluoride

CAS No. 2551-62-4 EC No. 219-854-2 Index No.

Chemical group

Sulfur compounds; fluorine compounds

Alternative Substances

Nitrogen

CAS No. 7727-37-9 EC No. 231-783-9 Index No.

Chemical group

Inorganic gases

Reliability of information

Evidence of implementation: there is evidence that the solution was implemented and in use at time of publication

Reason substitution

vPvB

Hazard Assessment

Substance to be substituted: Sulphur hexafluoride is not listed in the SUBSPORTplus Database and has no harmonised classification according to Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation). Alternative substances: Nitrogen is not included in the EU harmonized classification and is generally considered a non-toxic gas.

Description of Substitution

Nike sneakers fabricated with the so-called Nike Air technology have a cushion of gas in the sole to make them more comfortable and to attenuate shocks. Initially sulphur hexafluoride was used to fill the cushion, because it is a dense gas, practically non-toxic. Today it is well known that sulphur hexafluoride (SF6) is a greenhouse gas, about 22,000 times more powerful than carbon dioxide. Nike decided to substitute the fluoride and turned to the Energy and Environmental Resources Trust (ERT) for counselling. First choice was perfluoro propane but though this is less potent than SF6 it is still hazardous for Earth’s climate. The final choice was nitrogen a gas that is not toxic and does not contribute to the global warming. The company invested several millions in technological changes but reports say it saved the equivalent of millions of tons of carbon dioxide.

Case/substitution evaluation

Here, thorough research has successfully replaced a very environmentally harmful substance with a non-harmful one.

State of implementation

Full capacity

Enterprise using the alternative

www.nike.com

Availability ofAlternative

Available

Type of information supplier

Research

Contact

https://www.americancarbonregistry.org

Further information

Sulfur hexafluoride

Nitrogen MSDS from Sigma Aldrich can be found here

Danish EPA: Environmental Project No. 771 2003 Evaluation of the possibilities of substituting potent greenhouse gases (HFCs, PFCs and SF6)

Type of publication and availability

Case study presentation on internet

Date, reviewed

November 26, 2021