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 INO LIDAR lab

DAILY EVOLUTION

In the first plot the daily evolution of the size-distribution of aerosols as measured at INO 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

..........click HERE to know more about aerosol size distributions ............