Danger Dust

EPA size comparisons for PM particles

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

Particle pollution includes:

PM10 : inhalable particles, with diameters that are generally 10 micrometres and smaller; andPM2.5 : fine inhalable particles, with diameters that are generally 2.5 micrometres and smaller.

How small is 2.5 micrometres? Think about a single hair from your head. The average human hair is about 70 micrometres in diameter – making it 30 times larger than the largest fine particle.

What are the harmful effects of PM?

Particulate matter contains microscopic solids or liquid droplets that are so small that they can be inhaled and cause serious health problems. Some particles less than 10 micrometres in diameter can get deep into your lungs and some may even get into your bloodstream. Of these, particles less than 2.5 micrometres in diameter, also known as fine particles or PM2.5, pose the greatest risk to health.