Airborne particulate matter, known as PM, is one of the major components of smog' PM include microsc

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• Airborne particulate matter, known as PM, is one
  of the major components of smog. PM include
  microscopic particles in the air that are capable
  of being inhaled by humans.
• It is difficult to determine the mass
  concentration of these particles in air because
  the larger particles account for nearly all the
  mass.
• New instruments are capable of counting the
  number of these ultrafine particles, thus giving
  us a more meaningful indication of what we are
  inhaling.

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• TSI P-Trak
• Upon entering the instrument, particles pass
  through a saturator tube where they mix with an
  alcohol vapor. The particle/alcohol mixture is
  next drawn into a condenser tube where alcohol
  condenses on the particles causing them to grow
  into droplets that can be counted more easily.
  The droplets then pass through a focused laser
  beam, producing flashes of light. The light
  flashes are sensed by a photodetector and counted
  to determine particle concentration.

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Electrical Low Pressure Impactor (ELPI) DEKATI
http//www.dekati.com/elpi2.shtml

• Operation principle The gas sample containing
  the particles is first sampled through a unipolar
  corona charger. The charged particles then pass
  into a low pressure impactor with electrically
  isolated collection stages. The electric current
  carried by charged particles into each impactor
  stage is measured in real time by a sensitive
  multichannel electrometer. The components are
  housed in a single compact unit. Standard RS232
  port is provided for communication with a laptop
  or PC computer. The particle collection into
  each impactor stage is dependent on the
  aerodynamic size of the particles. Measured
  current signals are converted to (aerodynamic)
  size distribution using particle size dependent
  relations describing the properties of the
  charger and the impactor stages.

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Dekati ELPI
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• Scanning Mobility Particle Sizer (SMPS)
• Differential Mobility Analyzer (DMA)

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