PM2.5 are very small particles usually found in smoke. They have a diameter of 2.5 micrometres (0.0025 mm) or smaller.
PM2.5 particles are a common air pollutant. We measure PM2.5 at sites around Victoria.
Health effects of PM2.5 particles
Polluted air can affect human health and the environment. In Victoria sources of pollution like industry emissions, vehicle exhaust, smoke from fires and dust can impact our air.
A key indicator of air quality is the amount of PM2.5 in the air. PM stands for particulate matter and the 2.5 refers to size. To help you understand we mean matter that has a diameter of 2.5 micrometres or smaller. A micrometre is one thousandth of a millimetre.
In comparison, a fine grain of sand measures about 90 micrometres across and a human hair averages a width of about 75 micrometres. So PM2.5 particles are really small. Small enough for you to breath them deeply into your lungs.
People who are sensitive to air pollution might experience symptoms when PM2.5 levels are high. This could include young children, older people, pregnant women and people with allergies, heart or lung conditions.
They might experience symptoms like wheezing, coughing, tightness of the chest or difficulty breathing. If you’re worried about your symptoms, see your doctor or call NURSE-ON-CALL on 1300 606 024. And if you experience chest tightness or difficulty breathing call 000.
You can stay up-to-date with air quality in your area by visiting EPA AirWatch. Air quality data is categorised from Good to Extremely Poor. EPA AirWatch also includes air quality forecasts for Victoria. You can use forecasts to help plan your day.
For more information about smoke and air quality visit our website epa.vic.gov.au
Breathing in PM2.5 particles can affect your health. PM2.5 particles are small enough for you to breath them deeply into your lungs. Sometimes particles can enter your bloodstream.
People who are sensitive to air pollution might experience symptoms when PM2.5 levels are high. This includes people with heart or lung conditions. Symptoms can include:
- chest tightness
- difficulty breathing.
Call 000 if you experience chest pain or difficulty breathing.
Find out more about what to do when it’s smoky outside.
Sources of PM2.5 particles
Common sources of PM2.5 particles include:
PM2.5 on EPA AirWatch
- the last hour (1-hour average)
- the last 24 hours (rolling 24-hour average).
|Air quality category||PM2.5 µg/m3 averaged over 1 hour||PM2.5 µg/m3 averaged over 24 hours|
|Good||Less than 25||Less than 12.5|
|Extremely poor||More than 300||More than 150|
Air quality standards for PM2.5
We compare PM2.5 data to national air quality standards. These are incorporated into the State Environment Protection Policy (Ambient Air Quality).
There is currently no national standard for the one-hour PM2.5 average. For one-hour PM2.5 data, we use the value 62 µg/m3 to trigger a ‘poor’ air quality category.
|National standard||Averaging time|
|25 µg/m3||24 hours|
Read more about air quality
Reviewed 16 March 2021