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Measuring Particulate Matter: what size should we be monitoring?

Monitoring the quality of the air in your workspaces can be vital in ensuring the health of your staff – not just in a manufacturing environment but also in offices where large numbers of people work, or where ventilation may be poor.

Most people spend up to 90% of their lives indoors, so the cleanliness of the air they breathe while inside can have huge impacts on health.

There are various factors that can be measured to ensure air is clean and safe, but one of the most important is Particulate Matter.

What is Particulate Matter (PM) and why should we monitor it?

The UK government defines Particulate Matter as “everything in the air that is not a gas”[1], essentially all the tiny solid and liquid particles that are floating around in our environments. This can be everything from dust to toxic chemical compounds.

It can include carbon, complex organic chemicals, sulphate, nitrates, ammonium, sodium chloride, mineral dust, water, and a series of metals.

They come from different sources: primary and secondary.

Primary sources include things like road transport and fuels burned for industrial, commercial or domestic purposes. Secondary sources are formed in the atmosphere from chemical reactions of gases such as nitrogen oxides and volatile organic compounds (VOCs).

It is the small size of Particulate Matter that makes it a particular hazard as the smallest particles can enter the bloodstream and be transported around the body, causing problems for the heart, brain and other organs.

In the short term, exposure to some types of PM can cause unpleasant symptoms such as irritation of the nose, throat, eyes, and fatigue. Longer-term, certain types of PM can be responsible for cardiovascular diseases and cancers.

How is PM classified and what do the different measurements mean?

PM is defined by size, with three classifications:

  • Ultra fine: <0.1 micrometres (µm) in diameter
  • Fine: 0.1 to 2.5µm in diameter
  • Coarse: between 10µm and 2.5µm in diameter (typically things like dust and mould spores)

Health and safety standards across the world tend to focus on maximum concentrations of coarse and fine particles, but there are no set standards for anything below 2.5µm.

Generally, anything larger than 10µm is not of concern as the particles are not small enough to get deep into the lungs and therefore exhaled out again.

Anything between 2.5 and 10 µm is considered small enough to penetrate deep into the lungs, while anything smaller than 2.5 µm can end up in the lining of the lungs and eventually the bloodstream.

Measuring PM within the workspace

Because PM is often microscopic, and may not have an odour, indoor air quality monitors, like Pressac’s, are the easiest way of measuring PM within a workspace.

They provide continuous measurements of particle concentrations, producing valuable data and enabling trends to be tracked. If PM reaches a certain level, ventilation could be increased or an alert triggered to replace air filters.


How small should we go?

As previously mentioned, health standards across the world – including those set by the World Health Organisation and the UK government, tend to focus on 2.5 µm and above.

But a low PM2.5 reading does not mean that air is totally clean. It may be full of particles much smaller than this that still pose a potential health risk.

It is possible, and beneficial, to measure particles smaller than this, and there is increasing research being undertaken into the impacts of these smaller particles[1].

Many bacteria and viruses are classified as PM1 – so monitoring and responding to particles of this size could potentially help stop their spread.

The smaller a particle is, the larger the surface area it has, meaning there is a greater chance of toxic materials attaching themselves to its surface. It is also easier for it to penetrate deep into the body.

These smaller particles are likely to take longer to settle, meaning they remain suspended in the air for much longer periods of time – often several days.

Pressac’s sensors measure particles as small as PM1, meaning you can measure even smaller particles, giving extra reassurance that the air in your buildings is clean and safe.

In conclusion, equipping the workplace with IoT sensors can have a positive impact on the health and well-being of employees. By monitoring and controlling the levels of particulate matter, employers can create a safe and healthy indoor environment, which can lead to increased productivity and job satisfaction.

As research continues to explore the impact of PM on human health, it is important for employers to take proactive steps to ensure the safety of their employees.

[1] UK Government:


Pressac’s air quality sensors can measure PM 1/2.5/4/10, along with VOC levels, CO2, humidity and temperature, giving you clear insights into your building’s indoor air quality.

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