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IFAC Aerosol Size Distribution and PMx ONLINE
(Updated every 10 minutes)


Measuring the particles suspended in the air that we breathe is important, but is technically difficult.

Because of the broad range of particle sizes (from nanometers to hundreds of micrometers), at present several instruments must be used in order to measure their entire size distribution. The largest particles (from 0.3 um up) can be collected on filters
and weighted, or measured by means of optical instruments such as an Optical Particle Sizer (OPS). The smallest particles (which are still dangerous for our health because they can cause harmful chemicals to enter deep into our lungs) can be measured by means of electrostatic instruments, such as the SMPS (Scanning Mobility Particle Sizer).

Our SMPS (Grimm , CPC model 5.403, column 5.5-990) measures aerosol size distribution between 0.01 and 0.8 um, while the 1.109 Grimm OPS measures particles between 0.25 and 32 um.

By means of some hypothesis about the aerosol density, the instrument provides an estimate of "PMx" (particulate mass of particles with a diameter smaller than "x" um) in ug/m3, a well-known measurement in the field of health studies. We calculate PM1, PM2.5 and PM10 with a resolution of 10 minutes. The measurement and data treatment are automatized

The SMPS and the OPS sampling air outside the IFAC LIDAR lab




What is Aerosol ?

The finest particles (0.01-0.1 micron) are produced directly by natural nucleation or by combustion, and can contains dangerous chemicals such as soot, hydrocarbons and other organics compounds. Coarser aerosol ( larger than 1 um) are present in the form of dust, ash, or fog droplets. Large particles have a short life in the atmosphere due to sedimentation removal, while fine particles can survive for days or even weeks. Once emitted, the fate of fine particles follows the path of local meteorology: in the cases of a stable atmosphere near the ground, which often occurs in our town at night-time and in winter, a buildup of aerosol pollution can occur.

Here is an interesting review about aerosols and aerosol measurement techniques

Aerosols Online from IFAC CNR

Sesto Fiorentino (Florence , Italy)
- Measurements updated every 10 minutes


The plot shows with blue circles the latest (OPS+SMPS) Aerosol size-distribution measurement.
The black line is the best fit line as obtained by means of three lognormal modes (red, green, and blue lines).




In the first plot the daily evolution of the size-distribution of aerosols as measured at IFAC is represented over the 24 hours

- x axis: UTC time.
- y axis: Particle size (in nanometers)
- Colors: aerosol concentration

Red colors show high concentrations. The size distribution peak is often between 50 and 100 nm. These are the so-called "accumulation mode" aerosols, that is, "aged" aerosols that survive for a long time in the atmosphere. Particles just produced by combustion (and seldom by natural nucleation events) show their peaks around 20-50 nm, thus revealing their joung nature (which is often deleterious for health).


These other two plots show the

Surface and Volume distributions of submicron aerosols.

Aerosol surface is the key factor in the aerosol-health connection !!!


These other two plots show the Surface and Volume distributions of submicron aerosols. In this plot the SURFACE distribution is shown. Surface is usually dominated by accumulation-mode aerosols. Aerosol surface is the key factor in the aerosol-health connection !!!

Aerosol volume (here shown) and Aerosol mass are dominated by coarse particles
 HERE to know more about aerosol size distributions ............


PM-1, PM-2.5, PM10 values online (every 10 min.)
IFAC CNR Sesto Fiorentino (FI) ,Italy

The upper plot shows the PM1...PM10 mass concentration as obtained from the DMA+OPS measurements. An arbitrary particle density of 1.6 g/cc was considered in the calculations. The lower plot shows the contribution of PM1 and PM2.5 to PM10


Massimo Del Guasta - National Institute of Optics (INO) - National Research Council       |       Via Madonna del Piano, 10 - 50019 Sesto Fiorentino - Firenze, Italy  |   Tel (office): +39-055-5226423 - Tel (laboratory) +39-055-5226424   |   Email: Massimo Del Guasta  |   Web:  |   sito ottimizzato per una risoluzione minima di 1024x768 e firefox

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