Particules, also known as particle pollution (or PM), are made up of a number of components including nitrates and sulfates, organic chemicals, metals and soil or dust particles. 

Some particles such as dust, dirt, soot or smoke, are large or dark enough to be seen by the naked eye. Others are so small that they are invisible. 

Particle pollution mainly comes from motor vehicles, wood burning heaters and industry. 

During bushfires or dust storms, particle pollution can reach extremely high concentrations and present a risk to public health, especially for vulnerable groups.

Fine (PM2.5) particles in the air from smoke

Small or 'fine particles' are those with diameters that are 2.5 micrometres (µm) or smaller (designated as PM2.5) and are commonly found in smoke and haze.  For comparison, the average human hair is about 70µm in diameter, which is 30 times larger than the PM2.5 particles measured in air quality monitoring networks

Health effects of PM2.5 particles

PM2.5 particles are small enough to be breathed deep into the lungs and enter the bloodstream. This can impact a person’s health. 

Children, people over 65, pregnant women and people with existing heart or lung conditions (including asthma) are more sensitive to the effects of breathing in fine particles. Symptoms may include wheezing, chest tightness and difficulty breathing.

For more information read our factsheet on the health impacts of outdoor smoke

How the ACT Government monitors PM2.5 

PM2.5 is the most widely used indicator to assess the health effects from exposure to outdoor air pollution. It is also considered to be the best air pollutant indicator of potential health impacts from exposure to smoke. 

A one-hour average is the average levels of PM2.5 particles over a one-hour period. 

The 24-hour rolling average is the average of the hourly readings of PM2.5 over the previous 24-hour period. It is updated each hour.

Coarse (PM10) particles in the air from dust and dirt

Particles from vehicles on dirt roads and dusty industries, such as mining, crushing and grinding, are generally larger than 2.5µm in diameter and are included in PM10. Particles in dust storms also tend to be coarse in size.

Health effects of PM10 particles

Coarse particles are not easily breathed into the lungs. As such, they do not pose a serious health threat to the general public, although high levels of PM10 can irritate the eyes and throat.

People with existing heart or lung conditions (including asthma) can experience an increase in symptoms, including wheezing, chest tightness and difficulty breathing.

For more information read our factsheet on the health impacts of dust storms.

How the ACT government monitors PM10

A one-hour average is the average levels of PM10 particles over a one-hour period. The 24-hour rolling average is the average of the hourly readings of PM10 over the previous 24-hour period. It is updated each hour.

Page last updated on: 3 Sep 2019