Nanoparticles in the air we breathe

What are nanoparticles?

Let’s dive into nanoparticles or as the atmospheric scientists call them ultrafine particles (UFP) or PM0.1. The term nanoparticles applies to material engineering, eventually, both terms are the same thing. A nanoparticle is a microscopic particle with at least one dimension less than 100nm. One nanometer (1nm) is only three to five atoms wide.

Recent research suggests these nanoparticles could be responsible for illness and death beyond our current understanding. We know that PM2.5 is quite small and can penetrate deep inside our bodies and it can reach even the alveolar sacs where the exchange of oxygen and carbon dioxide occurs.
PM2.5 is around 2,500 nanometers (nm) in diameter. However, nanoparticles are 100nm (0.1μm) or less. In comparison, they are 25 times smaller, as a result, they can reach any organ in our bodies.

In the image below we can appreciate the sizes better. All of them are on the scale of nanometers. We can begin with the plastic nanoparticle (the term “nanoplastics” is still under debate) with an average diameter 100nm. Nanoplastics can be found in the air, scientists have found them even in remote locations because there are very easy to be carried by the wind currents. Then we can spot the gold (Au) nanoparticle that researchers use to experiment and magnetite (Fe3O4) nanoparticles easily produced by vehicle brake pads. For reference, I have placed the 25nm gate system on a chip (SOC) as modern computers/smartphones nowadays work on the nanometer scale. Apple’s A12 processor contains 6.9 billion transistors in ~9mm × 8mm chip. Finally, we can see a carbon nanotube with a diameter of 40nm.

Nanoparticles comparison

Government authorities monitor PM2.5 by mass micrograms per cubic meter (μg/m3), consequently, millions of nanoparticles may not even register in a single measurement by microgram. Some scientists worry that governmental reports under-represent the real danger. There aren’t any regulations for this size class of ambient air pollution particles, which are far smaller than the regulated PM10 and PM2.5 and are believed to have a more severe health impact than the PM2.5 and PM10.

Agglomeration of Nanoparticles

An agglomeration of a million nanoparticles can have the same mass as just one PM2.5 particle, but a combined surface area a thousand times larger.


All in all, nanoparticles pose a great threat, and scientists just start to understand the impact they have on human health. Not only their size is dangerous but the chemical composition of those particles. Could a plastic nanoparticle pass through the blood-brain barrier (BBB) and reach our brain?


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