The difference between PM10 and PM2.5 is size. But before we get to size, “PM” refers to particulate matter—particles in the air. Those particles are things like organic dust, airborne bacteria, construction dust, and coal particles from power plants.
Read more: If you’re curious what particles we’re breathing in polluted cities, check out this study from researchers in Shanghai who analyzed what those particles are really made of.
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5 Things You Should Know about PM2.5 Air Pollution
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Does Size Matter?
The “10” and the “2.5” refer to microns (AKA micrometers). Microns are tiny. Here’s an idea of how small microns are compared to human hair:
Next, there’s a hidden (unlabelled) detail in the terms “PM 10” and “PM 2.5.” That is the “smaller than” piece. Each pollutant type is defined as that size and below. So PM10 is particles 10 microns and below. PM2.5 is 2.5 microns and below. (That means PM10 includes PM2.5.)
What PM 10 and PM 2.5 Are Not
Finally, it’s helpful to think of what PM is not. Particulate pollution does not include gas pollutants like ozone and NO2. It also doesn’t include gas pollutants that often come from inside our home, such as formaldehyde off-gassing from new furniture.
On this page
- Overview
- Health effects
- Environmental effects
- Sources of emissions
- References
Description
PM10 is particulate matter 10 micrometers or less in diameter, PM2.5 is particulate matter 2.5 micrometers or less in diameter. PM2.5 is generally described as fine particles. By way of comparison, a human hair is about 100 micrometres, so roughly 40 fine particles could be placed on its width.
PM10 and PM2.5 are not used for any application.
Substance details
Substance name: Particulate matter (less than 10 micrometers in diameter or less than 2.5micrometres in diameter)
Synonyms: dust, particulate matter, inhalable particles, respirable particles, smoke, mist
Physical properties
Particles of any substances that are less than 10 or 2.5 micrometres diameter. Particles in this size range make up a large proportion of dust that can be drawn deep into the lungs. Larger particles tend to be trapped in the nose, mouth or throat.
Chemical properties
The chemical properties vary depending on sources of particles. It is important to note that particulates are not one particular chemical substance but a classification of particles by size rather then chemical properties.
Further information
The National Pollutant Inventory (NPI) holds data for all sources of Particulate matter (PM10) emissions in Australia.
- Australia's Particulate matter (PM10) emission report
- Australia's Particulate matter (PM2.5) emission report
Description
Recent epidemiological research suggests that there is no threshold at which health effects do not occur. The health effects include:
- toxic effects by absorption of the toxic material into the blood (e.g. lead, cadmium, zinc)
- allergic or hypersensitivity effects (e.g. some woods, flour grains, chemicals)
- bacterial and fungal infections (from live organisms)
- fibrosis (e.g. asbestos, quartz)
- cancer (e.g. asbestos, chromates)
- irritation of mucous membranes (e.g. acid and alkalis)
- increased respiratory symptoms, aggravation of asthma and premature death. The risks are highest for sensitive groups such as the elderly and children.
The factors that may influence the health effects related to exposure to particles include:
- the chemical composition and physical properties of the particles
- the mass concentration of the airborne particles
- the size of the particles (smaller particles may be associated with more adverse effects because they can be inhaled more deeply into the lungs)
- the duration of exposure (short and long term, possibly in years).
Entering the body
Particles in the PM10 size range are commonly present in air and may be drawn into the body with every breath. In the lungs particles can have a direct physical effect and/or be absorbed into the blood. Airborne particles, not only the PM10 fraction, may also may be deposited in the mouth, throat or nose and be ingested.
Exposure
All people are continuously exposed to some extent except in special filtered environments. Exposure may be higher in urban and industrial areas due to an increase in the number of sources, however high levels may also occur in natural environments.
National Ambient Air Quality Standards
Under the National Environment Protection Measure for Ambient Air Quality, Australian governments have set a national ambient air quality standards for particulate matter.
PM10
- 50 µg/m3 in outdoor air averaged over a 24-hour period
- 25 µg/m3 in outdoor air averaged over a year
PM2.5
- 25 µg/m3 in outdoor air averaged over a 24-hour period
- 8 µg/m3 in outdoor air averaged over a year
Workplace exposure standards
Safe Work Australia sets the workplace exposure standards for particulate matter through the workplace exposure standards for airborne contaminants. These standards are only appropriate for use in workplaces and are not limited to any specific industry or operation. Make sure you understand how to interpret the standards before you use them.
Coal dust
- Maximum eight hour time weighted average (TWA): 3 mg/m3
Cotton dust, raw
- Maximum eight hour time weighted average (TWA): 0.2 mg/m3
Fume
- Maximum eight hour time weighted average (TWA): 2 mg/m3
Grain dust
- Maximum eight hour time weighted average (TWA): 4 mg/m3
Nickel sulphide roasting fume and dust
- Maximum eight hour time weighted average (TWA): 1 mg/m3
Rogue dust
- Maximum eight hour time weighted average (TWA): 10 mg/m3
Soapstone dust
- Maximum eight hour time weighted average (TWA): 3 mg/m3
Wood dust (certain hardwoods such as beech & oak)
- Maximum eight hour time weighted average (TWA): 1 mg/m3
Wood dust (soft wood)
- Maximum eight hour time weighted average (TWA): 5 mg/m3
- Maximum short term exposure limit (STEL): 10 mg/m3
Caprolactam dust
- Maximum eight hour time weighted average (TWA): 1 mg/m3
- Maximum short term exposure limit (STEL): 3 mg/m3
e-Caprolactam dust and vapour
- Maximum eight hour time weighted average (TWA): 10 mg/m3
- Maximum short term exposure limit (STEL): 20 mg/m3
Emery dust
- Maximum eight hour time weighted average (TWA): 10 mg/m3
Zinc oxide dust
- Maximum eight hour time weighted average (TWA): 10 mg/m3
Vandium dust and fume
- Maximum eight hour time weighted average (TWA): 0.05 mg/m3
Aluminium dust
- Maximum eight hour time weighted average (TWA): 10 mg/m3
Lead dust and fumes
- Maximum eight hour time weighted average (TWA): 0.05 mg/m3
Manganese, dust and compounds
- Maximum eight hour time weighted average (TWA): 1 mg/m3
Tantalum, metal and oxide dusts
- Maximum eight hour time weighted average (TWA): 5 mg/m3
Cobalt, metal dust and fume
- Maximum eight hour time weighted average (TWA): 0.05 mg/m3
Copper dusts and mists
- Maximum eight hour time weighted average (TWA): 1 mg/m3
Fumed silica
- Maximum eight hour time weighted average (TWA): 2 mg/m3
Graphite excluding fibres
- Maximum eight hour time weighted average (TWA): 3 mg/m3
Ferrovanadium dust
- Maximum eight hour time weighted average (TWA): 1 mg/m3
- Maximum short term exposure limit (STEL): 3 mg/m3
Cristobalite dust
- Maximum eight hour time weighted average (TWA): 0.1 mg/m3
Quartz dust
- Maximum eight hour time weighted average (TWA): 0.1 mg/m3
Trydymite dust
- Maximum eight hour time weighted average (TWA): 0.1 mg/m3
Perlite dust
- Maximum eight hour time weighted average (TWA): 10 mg/m3
Drinking water guidelines
The Australian Drinking Water Guidelines do not relate to inhalable substances.
Description
PM10 may affect animals in the same way as it affects humans. Particles in general, not specifically PM10 or PM2.5, affect the aesthetics and utility of areas through visibility reduction and may affect buildings and vegetation. The specific effect of particles depends on their composition, concentration and the presence of other pollutants such as acid forming gases.
Entering the environment
Particles in the air affect both the quality of the air and visibility. Once in the air particulate matter generally takes a long time to settle. The particulates may be washed from the air by rain or snow. When they settle on land they may settle permanently or be re-entrained. In water particulates may settle, dissolve or both.
Where it ends up
PM10 and PM2.5 are very fine and light and are therefore easily entrained into the air by wind or disturbances. Chemical changes may occur, as may reactions with other substances, depending on the composition of the particles. Particles may stick together or break apart, changing the size distribution over time.
Environmental guidelines
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Industry sources
PM10 and PM2.5 are produced from a wide range of industrial processes through bulk material handling, combustion and minerals processing. The industries using these processes include brickworks, refineries, cement works, iron and steel making, quarrying, and fossil fuel power plants.
Diffuse sources, and industry sources included in diffuse emissions data
Particulates are released from a wide range of diffuse sources. Examples include lawn mowing, wood stoves, fires, and wind generated dust, though this tends to be coarser.
Natural sources
Natural sources of PM10 and PM2.5 include bushfires, dust storms, pollens and sea spray.
Transport sources
Vehicles will generate particulates either from direct emissions from the burning of fuels (especially diesel powered vehicles) or from wear of tyres or vehicle-generated air turbulence on roadways. Particles may also be generated from the action of wind on the dusty material that the vehicle may be carrying.
Consumer products
Particulates are not generally included intentionally in any product but may be present as part of the product, for example as part of talc or other powder products.