What is Particulate Matter?

Particulate matter is a composition of different types of small dust particles. These dust particles have physical and chemical properties.

If these dust particles themselves are in the air, there is talk of primary dust, but when they end up in the air as a result of certain reactions, then we are talking about secondary dust.

What is PM1, PM2.5 and PM10?

The particles of particulate matter (solid, suspension or liquid) that have various dimensions and compositions are also called “aerosols”. They can be categorized under the heading of “floating dust” and are often expressed in PM.

PM is short for ‘particulate matter’ and that is a concept to indicate exactly how large such a dust part is. Particulate matter is indicated as PM 1, PM 2.5, and PM 10.

PM10 indicates that a particulate matter has a diameter of 10 micrometers. It is also expressed by 10 μm (1μm = 1 millionth of a meter or 1 thousandth of a millimeter). Below you will find a visual representation of how small these dust particles are.

particulate matter particle size
particulate matter particle size

To give an indication of how small particulate matter can be, the example of human hair is usually used. The average diameter of human hair usually varies between 50 and 70 μm.

A PM 2.5 dust particle can therefore fit as much as 20 to 28 times in the thickness of a human hair, so it’s very small. A PM 2.5 dust particle has a diameter of 0.0025mm.

What are the causes of particulate matter?

As previously indicated, a distinction is made between primary and secondary substance. Primary dust is therefore particulate matter that is the result of natural processes (natural sources). Some examples are sea salt, soil erosion, supply of desert sand or volcanic eruptions, but even pollen (plant origin) are natural sources of particulate matter.

The sources of secondary dust can be traffic, agriculture, industry, heating of buildings etc.

Is particulate matter harmful to health?

Particulate matter, like volatile organic compounds, is harmful to health. Exposure to high concentrations of these has shown that there are increasing respiratory infections and emergency admissions in the hospitals.

Respiratory symptoms then increase and there may even be a pungent cough and asthma or worsening. This also increases the demand for certain medications. If there is prolonged exposure to particulate matter, this can lead to permanent damage such as impaired lung function or chronic respiratory diseases.

In addition, dust particles that come from combustion processes are carcinogenic.

Furthermore, particulate matter can also cause the blood vessels of the body to clog up, resulting in an increased risk of heart attacks. Enough reason to worry about particulate matter.

It is important to know that dust particles larger than 10 micrometers are held by the hairs in our nose and excreted by the mucous membrane. This means that they do not penetrate. The dust particles that are smaller than 10 micrometers penetrate through the nasal cavity into our body and then enter the airways and lungs. That is why there are health problems in these parts of the body.

What are the air quality standards for particulate matter?

It is important to distinguish between emissions and concentrations. For example, emissions are expressed in the number of tonnes per year and indicate particulate matter sources of agriculture, traffic, industry, etc. Outdoor concentrations are expressed in micrograms per cubic meter or μg/m3 and indicate the extent of those emissions.

The World Health Organisation (WHO) has other advisory values and stricter limit values compared to European limit values. For the WHO, there is no safe threshold for particulate matter under which there can be no negative consequences. The less particulate matter there is, the better.

PM10 Subject Averaging Objective
EU Directive 2008/50/EC* Limit 1 day 50 μg/m³; Max. 35 overruns per year
1 year 40 μg/m³
WHO Advisory value 1 day 50 μg/m³; Max. 3 overruns per year
1 year 20 μg/m³

* Since 1 January 2005, the limit value for PM10 must be respected.

PM2.5 Subject Averaging Objective
EU Directive 2008/50/EC Limit 1 year 25 μg/m³ from 2015
Indicative limit value * 20 μg/m³ from 2020
WHO Advisory value 1 day 25 μg/m³; Max. 3 overruns per year
1 year 10 μg/m³

* May be reviewed by the European Commission later.

What is the difference between particulate matter and smog?

Smog is simply a combination of smoke and polluted fog and can also contain a quantity of particulate matter. If there is smog, there is a high concentration of air pollution and the concentration of ozone, particulate matter, nitrogen dioxide, and sulfur dioxide is above the warning or alert threshold.

In the table below, you can see when the alert or alert threshold is exceeded.

  Ozone hourly average Fine dust (PM10) 24-hour average Nitrogen dioxide hourly average Sulfur dioxide hourly average
Warning from: 180 70 200 350
Alarm from: 240 100 400 500

How do you measure particulate matter?

You can measure the degree or amount of particulate matter that is present in your home with a special device or fine dust meter.

You also have devices that not only measure particulate matter, but can also detect other hazardous substances and indicate the amount of those substances present in the indoor air. It is important to make regular measurements regarding indoor air pollution. Especially from the indoor air of spaces where you and your family spend a lot of time.

A healthy – and above all clean living environment is important for a healthy life. If you want to do the measurement yourself, you can also purchase sensors. The price of the sensors may vary depending on the model, brand, and what the product offers. You can also have a professional company come and do the measurement for you.

How can you reduce particulate matter?

Now that it is known how harmful particulate matter can be, you want to do everything you can to prevent you from coming into contact with this substance too much. A very simple way to reduce particulate matter in your home is to purchase a good air purifier.

When purchasing an air purifier, pay attention to the size of the room. Another simple way is to vent the rooms regularly. Make use of the windows and doors of the room and leave them open to fresh air as often as possible.