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Instrument: TEOM : Tapered Element Oscillating Microbalance
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Description
In the Tapered Element Oscillating Microbalance (TEOM), the air
is sucked in through the sampling head which restricts the size
of the particle entering the device (for instance a PM10
sampling head will only allow particles with a diameter less
than or equal to 10 micro-meters). Some of the air then passes
through the filter within the tapered element oscillating
microbalance and as the number of particles deposited increases
the natural frequency of the vibration of the element
decreases. There is therefore a direct relationship between the
change in the vibrating frequency and the mass on the filter.

The TEOM measures the mass of the particles and allows 15-minute
average readings, which is very useful for tracking pollution
incidents as it allows real time analysis. However, it tends to
under-read the particle levels monitored compared with the
Partisol Plus Unit as it is heated to prevent water entering the
device, and therefore many of the volatile particles are
evaporated.

[Summary provided by The Royal Borough of Kensington and Chelsea]