Fluorine, present in its molecular form F₂, is used in the chemical industry to manufacture fluorinated compounds and in the nuclear industry to produce uranium hexafluoride.
At room temperature, it is a pale yellow, almost colourless gas, heavier than air, with a characteristic irritating odour. It is extremely reactive. This factsheet concerns elemental fluorine, rather than hydrogen fluoride, HF, or fluoride salts.
1Main properties
A simple indication of “solubility in water” does not adequately describe its behaviour: fluorine reacts chemically with water.
2What are the hazards?
Fluorine is fatal if inhaled and highly corrosive. It can cause severe skin burns, serious eye damage and significant respiratory tract injuries.
Its strong reactivity with mucous membranes leads notably to the formation of hydrogen fluoride and fluoride ions. The lungs are a major target of its toxicity; significant exposure can cause severe lung injuries.
Fluorine is an oxidising gas: it can cause or intensify a fire. It reacts with numerous substances, sometimes causing ignition or an explosion, particularly with hydrogen, organic materials and water. Material compatibility is therefore essential.
3What occupational exposure limits apply?
The INRS factsheet dated June 2023 reports the following indicative regulatory occupational exposure limits established in France in 2004:
| Reference period | ppm | mg/m³ |
|---|---|---|
| 8-hour average | 1 | 1.58 |
| Short-term, 15 minutes | 2 | 3.16 |
These limits apply to fluorine F₂. They must not be confused with those for hydrogen fluoride or fluorides, and do not, on their own, constitute gas detector alarm settings.
4How can risks be prevented?
Prevention relies on installations specifically designed for fluorine, closed processes, emission capture and suitable ventilation. Equipment, fittings and hose materials must be compatible with the substance and its operating conditions.
INRS recommends frequent atmospheric checks, preferably continuous monitoring supplemented by an automatic alarm.
Skin, eye and respiratory protection must be selected according to the risk assessment and safety data sheet. Many common glove materials are incompatible: their suitability for fluorine must be confirmed.
Cylinders must be stored upright and secured, in a cool area with continuous mechanical ventilation, protected from heat and in accordance with the supplier’s instructions.
Source: INRS, Toxicological Factsheet No. 203, “Fluorine”, June 2023 edition, in French.