What are pm2.5 fine particles?

Today we are talking about air pollution, with a focus on fine particles PM 2.5

At R-PUR, we are convinced that a global understanding of air pollution would make it possible to change mentalities more quickly.

We therefore have at heart to explain simply what are these invisible and odorless particles that do a lot of damage to our organism.

You can also find our dedicated article on the air quality index , which will explain why this tool is essential for your health.

What is PM2.5, definition and measurement?

The particulate matter or PM (Particle Matter in English) is a physical particle: it is therefore defined by a size (unlike a gas)

It is more commonly called a fine particle because it is very small in size.

You could thus observe it with an entry-level microscope: its size is between a bacterium and a red blood cell .

On a daily basis, to determine whether the atmosphere is polluted, we rely on the AQI , which is an air quality index.

The AQI is calculated by taking into account the measurements of the six main pollutants: PM2.5 is the smallest measured suspended physical particle of this index.

What are fine particles
and where do they come from?

You are now able to visualize what PM2.5 suspended particles represent, the question now is to know where they come from .

Before continuing, it is important to remember that there is not just one PM2.5.

Indeed, when we talk about fine particles, we classify them by size, so they can come from different sources and not look alike if we had to compare them under the microscope.

They are formed from a complex mixture of solid and liquid particles of organic and mineral substances suspended in the air.

More simply, they mainly come from France:

• wood heating
• road transport, particularly diesel vehicles
• industries

Now that we are able to better situate them, what are their effects on human health , in the short and long term.

What does the World Health Organization (WHO) say about these effects?

In recent years, we have known more precisely the effects of these suspended particles on human health.

PM2.5 is so fine that it can lodge deep in our lungs .

They do a lot of damage to our body: even at low concentrations, small particle pollution has a health impact.

Among the long-term causes:

• 60% cardiovascular accidents
• 20% COPD: chronic respiratory disease
• 10% lung cancer

They also do short-term damage to our body:

• Cough
• Itchy eyes
• irritated throat

PM2.5 measurements are expressed in µg/m3 , with an average over the year recommended by the World Health Organization (WHO) of 10 µg/m3

AirParif tells us that in 2018, this regulation was exceeded for around 10 million inhabitants in Île-de-France, i.e. 85% of Ile-de-France residents (between 14 and 18 µg/m3 near road traffic)

Source: City of Paris with Airparif

However, there have been positives for several years, the level of PM2.5 particles in the atmosphere has been falling and there are fewer episodes of intense pollution on average over the year.

Where does France stand in terms of European regulations?

France is the bad student when it comes to PM2.5: in 2018 it rejected no less than 164,000 tonnes of PM.25, the largest total in all of Europe.

When we carried out this in-depth study, we were surprised how enormous this figure seemed to us given the size of a PM2.5 pollutant.

We are convinced that the information accessible to the greatest number will allow a collective awareness necessary to make the air breathable for future generations.

We can also note a positive side: by slightly changing our consumption habits, France could meet the objectives set by the WHO in terms of regulations by 2030 .

For example, road traffic tends to decrease with the progression of soft mobility such as cycling in our cities: we could then have a direct impact on the air quality on average over the year.

How to filter PM10 and PM2.5 fine particles? What about anti-pollution masks?

When the air quality is poor, such as during episodes of pollution or pollen , more and more people affected by the problem seek to protect themselves.

They can then turn to an anti-pollution mask.
Two essential parameters must be taken into account:

. Efficiency : what pollutants will my mask filter and to what extent.

. Hermeticity : in other words, will outside air enter my mask.

For example, if 40% of the air were to enter your mask, which is the most effective in the world, there would not be much point in wearing it in the middle of road traffic.