Suspension of fine solid particles or liquid droplets in air or another gas
The same hypothetical log-normal aerosol distribution plotted, from top to bottom, as a number vs. diameter distribution, a surface area vs. diameter distribution, and a volume vs. diameter distribution. Typical mode names are shown at the top. Each distribution is normalized so that the total area is 1000.

Change in time = Convective transport + brownian diffusion + gas-particle interactions + coagulation + migration by external forces

The Knudsen number of the particle define three different dynamical regimes that govern the behaviour of an aerosol:

Kelvin equation for saturation vapor pressure above a curved surface is:

Stability of nanoparticle agglomerates is critical for estimating size distribution of aerosolized particles from nano-powders or other sources. At nanotechnology workplaces, workers can be exposed via inhalation to potentially toxic substances during handling and processing of nanomaterials. Nanoparticles in the air often form agglomerates due to attractive inter-particle forces, such as van der Waals force or electrostatic force if the particles are charged. As a result, aerosol particles are usually observed as agglomerates rather than individual particles. For exposure and risk assessments of airborne nanoparticles, it is important to know about the size distribution of aerosols. When inhaled by humans, particles with different diameters are deposited in varied locations of the central and periphery respiratory system. Particles in nanoscale have been shown to penetrate the air-blood barrier in lungs and be translocated into secondary organs in the human body, such as the brain, heart and liver. Therefore, the knowledge on stability of nanoparticle agglomerates is important for predicting the size of aerosol particles, which helps assess the potential risk of them to human bodies.

A standard deagglomeration testing procedure could be foreseen with the developments of the different types of existing systems. The likeliness of deagglomeration of aerosol particles in occupational settings can be possibly ranked for different nanomaterials if a reference method is available. For this purpose, inter-laboratory comparison of testing results from different setups could be launched in order to explore the influences of system characteristics on properties of generated nanomaterials aerosols.

particles which pass through a size-selective inlet with a 50% efficiency cut-off at 10 μm aerodynamic diameterparticles which pass through a size-selective inlet with a 50% efficiency cut-off at 2.5 μm aerodynamic diameter

Aerosols can be found in urban ecosystems in various forms, for example:

The presence of aerosols in the earth's atmosphere can influence its climate, as well as human health.