A new enemy in the air: the nanoparticle

01/06/2023

Emmanuelle Saux

As the world’s fourth leading source of mortality, air pollution is becoming a major health issue.

Caused by the production of atmospheric pollutants generated by transport, industrial activities, the residential sector (heating) and agriculture, this pollution has a considerable impact on our health.

Very often concentrated in urban areas, but not only there, air pollution creates a thick fog, revealing the density of micro-particles present in the environment. Cardiovascular disease, chronic lung disease, lung cancer, etc… Responsible for one in ten deaths worldwide, air pollution causes 40,000 premature deaths in France every year.

The toxic elements and particles that make up air pollution include :

nitrogen dioxide (NO2) ;
sulfur dioxide (SO2) ;
ozone (O3);
fine and ultra-fine particles (PF and PUF)

Fine particles, with a diameter of less than 10 microns, remain suspended in the air, and above all have harmful effects on respiratory functions and skin health. Depending on their size, the impact on our health will vary. PM10 (10 microns) affects the cardiovascular system, while PM2.5 (2.5 microns) attacks the neurological system. PM2.5 are small enough to penetrate deep into the alveoli of the lungs, and even through paper masks. On the skin, fine-particle pollution increases the expression of proteins that degrade certain dermal components, accelerating skin aging.

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Lowering the limit value to 5 µg/m3 (instead of the current 25 µg/m3) would result in a reduction of

0 %

the number of deaths linked to air quality!

Nanoparticles, do you know anything about them?

Today, only PM10 and PM2.5 are regulated for their negative effects on health. But there are also ultra-fine particles, known as nano particles, which are the smallest we can measure and observe today.

These nano particles, or PM0.1, are less than 0.0001 microns in size, which corresponds to the size of a virus or a DNA molecule. Considered even more harmful than the fine particles mentioned above, ultrafine particles penetrate more deeply into the body, generating respiratory and cardiovascular diseases, diabetes, hypertension, and impacts on foetal development. The French National Agency for Environmental, Food and Occupational Health Safety published a report on the subject last July, sounding the alarm on the fact that ultra-fine particles are capable of reaching the bloodstream. As a result, they are more harmful than PM10, which is stopped by the respiratory tract.

The difficulty with these PM0.1 is that they are much smaller, but also more numerous (80 to 87%), while in terms of mass they weigh practically nothing. Measuring them therefore becomes a real technical challenge that only a few devices are capable of meeting. This device, an electrically powered granulometer spectrometer, is rare in France, and PM1 measurements are still uncommon.

Measuring air pollution

Today, it is mainly the larger particles that are measured by the fixed stations operated by the eighteen associations approved by the French government to monitor air quality. They measure PM2.5 and above all PM10, for which France regularly exceeds the regulatory threshold. For PM0.1, the measurements taken remain exceptional and, in the absence of regulations, these data are collected for information purposes only.

Jean-Baptiste Renard, Research Director at CNRS, considers that monitoring of these nanoparticles is not sufficient. In his view, “their average annual and daily concentrations are too high in relation to the recommendations. The new standards set by the WHO (5 µg/m3 annual average instead of 10 µg/m3) are far from being achieved in cities; drastic measures would be necessary to achieve them”, continues Jean-Baptiste Renard. In France, the limit value is much higher, at 25 µg/m3 annual average. According to Jean-Baptiste Renard, “if we lowered it to 5 µg/m3, we would reduce the number of air-quality-related deaths by 80%!

In the meantime, ultrafine particles are flying under the radar, despite evidence that they are dangerous. In the transport sector, for example, new diesel engines no longer emit PM10 and PM2.5, but they still spew out ultrafine particles, which are therefore not taken into account. Jean-Baptiste Renard comments on this subject: “Since we don’t measure it, we say that these vehicles don’t pollute. By saying that, we’re not properly protecting the population.” Here we see the relevance of decarbonizing transport very quickly!

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