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Nanoparticles in air

What is nanoparticle concentration?

Nanoparticles are classified into three categories: natural, “anthropogenic” and manufactured nanoparticles. In ambient atmospheres (office, housing, …), the average concentration of nanoparticles is in the region of 103 to 5x104 part.cm-3 (for particles having a median diameter less than 2x102 nm). But these values vary widely in time and space.

An important and fluctuating background noise depending on the context

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Variability of densities in presence of a disturbance.

The temporal background noise is important variable in the absence of disturbance.

In a locked office (without any external disturbance), the total concentration of particles (in the range of 5 and 350 nm) fluctuates from 15 % to 20 % in few minutes.

The density varies considerably depending on the context.

For the range of nanoparticles > 10 nm, the concentration can be as high as 8x107 part.cm-3 in the plume of a cigarette (average diameter of 18 nm) or 8x104 versus 10 particles in our one millimeter side cube.