Magnesium oxide fume: Sources of emissions


Magnesium oxide fume does not have any common use. Magnesium oxide is used as a component of refractory crucibles, fire bricks, insulation, rubber compounds, magnesia cements and boiler scale compounds. It is also used as a reflector in optical instruments and as a white colour standard.

Substance details

Substance name: Magnesium oxide fume

CASR number: 1309-48-4

Molecular formula: MgO

Synonyms: include airborne magnesium oxide and magnesia fume.

Physical properties

Magnesium oxide fume is an odourless white opaque smoke. Solid magnesium oxide is a hygroscopic fine white powder. Evaporation at room temperature is negligible. It has the following physical properties.

Melting Point: 2852°C

Boiling Point: 3600°C

Specific Gravity: 3.58

Chemical properties

Magnesium oxide fume is slightly soluble in water. The pH of a saturated aqueous solution is 10.3. Solid magnesium oxide is insoluble in alcohol, slightly soluble in water, and soluble in dilute acids and ammonium salts. It reacts violently with strong acids and halogens.

Further information

The National Pollutant Inventory (NPI) holds data for all sources of magnesium oxide fume emissions in Australia.


Breathing freshly generated magnesium oxide fume can irritate the eyes and nose. It can cause metal fume fever triggering symptoms such as headache, cough, sweating, nausea, fever, oppression in the chest and leucocytosis (increase in the number of white blood cells in the blood). The symptoms of metal fume fever might not become manifest until 4-12 hours after exposure and may last for 24 hours. Metal fume fever is not believed to have permanent effects. No chronic (long-term) health effects are known at this time.

Entering the body

Magnesium oxide fume can be inhaled.


Inhalation of magnesium oxide can occur in industrial workplaces. Exposure can usually be minimised by adequate ventilation at the site of formation. A respirator may be required in some situations.

Health guidelines

Worksafe Australia defines magnesium oxide as hazardous and has set the exposure standard for magnesium oxide fume to 10 milligram/m3 (TWA).


There is very little information available on the environmental effects of magnesium oxide fume. If other mammals inhale magnesium oxide fume, they may suffer similar effects as do humans.

Entering the environment

Magnesium oxide fume can be transported in air.

Where it ends up

Magnesium oxide fume is diluted in air to levels which do not affect the environment.

Environmental guidelines

No national guidelines.

Industry sources

In any industrial workplace where magnesium and magnesium compounds and alloys are used in "hot" operations such as welding, brazing, soldering, plating, cutting and metallising, magnesium oxide fumes may be formed due to the high temperatures reached in these operations. Examples include welding operations with magnesia in fluxes or the combustion of magnesium metal.

Diffuse sources, and industry sources included in diffuse emissions data

Sub-threshold facilities.

Natural sources

There are no natural sources for magnesium oxide fume.

Transport sources

There are no mobile sources for magnesium oxide fume.

Consumer products

There are no consumer products that produce magnesium oxide fume under normal conditions.

Sources used in preparing this information

  • ChemFinder WebServer Project (1995), Magnesium oxide (accessed, May, 1999)
  • National Environment Protection Council (1998), National Environment Protection Measure for the National Pollutant Inventory. (accessed, March, 1999)
  • New Jersey's Department of Health, Right to Know Hazardous Substance Fact Sheets (December 1996), Magnesium oxide (fume) (accessed, May, 1999)
  • Technical Advisory Panel (1999), Final Report to the National Environment Protection Council.
  • Worksafe Australia (1996), Exposure Standards Database, Magnesium oxide fume (accessed, May, 1999)
  • Worksafe Australia (1996), Hazardous Substances Database, Magnesium oxide (accessed, May, 1999)