What is Silica Dust?

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PM stands for particulate matter (also called particle pollution): the term for a mixture of solid particles found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye (PM10). Others are so small they can only be detected using an electron microscope (PM2.5).

Dust is made up of many different materials that are suspended and blown about in the air. Dust is an example of airborne particle pollution that affects the air we breathe.

Dust is generated from many different sources, such as unsealed roads, dry lake beds, cattle feedlots and premises where quarrying, concrete crushing, or metal recycling is carried out.

The size of dust particles depends on where they come from. Coarse (large) particles are often found near unsealed roads and quarries, whereas fine (small) particles typically come from motor vehicle exhausts and smoke from fires. Coarse particles tend to be deposited closer to the source, whilst fine particles can be carried a long way, especially on a windy day.

Coarse dust particles can be a nuisance when they get into houses or discolor washing on the line. Fine particles are responsible for reducing visibility and for dirtying buildings and, when concentrated enough, can become a health concern.

Some dust particles come from natural sources. Such particles include pollen grains, fungal spores and salt crystals from sea spray. Occasionally during very dry weather, dust can be lifted from soils, causing a dust storm.