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What is hexavalent chromium?
Hexavalent chromium or chromium VI is the 6th oxidation state of chromium. Hexavalent chromium is also known by its synonyms :
- chromium trioxide ;
- chromic anhydride ;
- chromium VI oxide ;
- chromium anhydride ;
- chromic trioxide.
The main substances containing hexavalent chromium or chromium VI are as follows:
Potassium dichromate
Sodium and potassium dichromates
Strontium chromate
Hexavalent chromium and its compounds are mainly used in the following industries:
- steel industry (chromium for the production of stainless steels, special steels and alloys);
- chemical industries (production of chromium compounds) ;
- Surface treatment (electrolytic chromium plating, hard chromium plating, decorative chromium plating);
- woodworking industries (conservation) ;
- manufacture of pigments and dyes ;
- leather tanning ;
- Aerospace (corrosion-resistant paint, sanding, grinding, etc.) ;
- Aircraft maintenance (paint rework) ;
VLEP hexavalent chromium: 8-hour and short-term occupational limit value
Hexavalent chromium and its compounds are chemical substances chemical substances classified as CMR (carcinogenic, mutagenic or toxic to reproduction): C1A, M1B, R2.
Decree 2020-1546 of December 9, 2020 sets binding occupational exposure limit values(OELVs) for hexavalent chromium and its compounds.
8-hour occupational limit value (VLEP-8h) = 0.001 mg/m³ Short-term occupational limit value (VLCT) = 0.005 mg/m³
Binding and indicative TLVs introduce a reference value when assessing workers’ exposure to pollutants in the workplace. Measurements of pollutant concentration levels in workplace air help determine which risk prevention measures to implement.
Also read: What are the risks of not complying with VLEP?
The concentration of chemical agents in the atmosphere of workplaces is expressed in :
- mg/m³ for liquid and solid aerosols ;
- ppm (parts per million) or ml/m³ for gases and/or vapors ;
- fibers/cm³ for fibers.
The occupational exposure limit value is measured on :
- an 8-hour reference period for 8-hour VLEP ;
- a maximum duration of 15 min for short-term TLVs.
What forms does chromium VI or hexavalent chromium come in, and how can it be treated?
Chromium 6 is generally found in the form of dust or contained in dust. This pollutant is generated during machining, shaping or reworking operations on materials containing or coated with chromium VI.
Hexavalent chromium in dust form is treated on particulate filters of class H and/or HEPA H13 or H14 minimum. You can find all VOC treatment solutions at https://obera.fr/produits/depoussiereurs-industriels.
Further information: VLEP regulations, chemical risk assessment in the workplace.
