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Dust is generally understood
to be an aerosol of solid particles, mechanically
produced, with individual particle diameters of
0.1µm upwards and can be a problem in almost
any industry, from bakeries to building sites.
Nuisance
dust is generated by a wide range of activities,
including traffic; construction/demolition;
mineral workings and general industry. |
With increasing awareness of
the problems caused by dust generated from such
works, many local authorities are now including
dust monitoring as a planning requirement. Often
there is a requirement to undertake a baseline
survey, particularly as part of an EIA, in order
to formulate acceptable thresholds.
Generally, two different approaches
are used to measure the amount of dust deposited
on a surface;
- Determination of the soiling
of a surface, by a change in its properties
- Determination of the quantity of dust deposited,
by weight
Within these approaches there
are a number of different methodologies these
include;
Deposit gauges - simple
and yet accurate methods for the measurement of
nuisance dust. Dust is collected onto a horizontally
mounted capture container, or in the case of the
Directional Dust Gauge, into four vertical tubes
aligned in different directions.
Dust samples collected
are measured by washing the collecting container
and foam insert through to a collecting bottle.
The sample is passed through a pre-weighed filter,
conditioned and re-weighed. The quantity collected
over a known area and period can be calculated
to give a deposition rate. We can also analyse
the dust to determine content of particular substances.
Collection Methods/Devices
Include;
The Frisbee type gauge
(illustrated) – A dust sample
is collected in a large capacity collection bottle
at the base of the unit. Gauges are fitted with
a stainless steel and nylon bird guard to avoid
extraneous contamination and mounted on a tripod
which can be spiked to the ground for increased
stability. The Frisbee gauge is generally accepted
to have the greatest sampling efficiency of those
available.
The BS1747 Directional
Dust Gauge - uses four tubular collectors,
positioned to distinguish between dust from four
compass points. The dust in each collector is
calculated as that of the Frisbee gauge to establish
a concentration from each point of the compass.
The Bergerhoff Gauge is the
simplest of all the deposit gauges as they consist
of a collecting container mounted on a pole.
Soiling Rate Measurement
- simple but effective methods used to determine
changes in the soiling rates of surface over a
period of time. Directional soiling rates can
also be measured.
The most popular soling rate
measurement method is the Sticky Pad system which
measures the soiling of a white adhesive surface
over a known period and gives a measurement of
the deposition (as percentage Effective Area Coverage
(%EAC) per day) using a reflectometer.
In this method, Fablon pad monitoring
stations can be used to provide an indication
of the relative deposition from different directions.
This method is attributed to
Beaman & Kingsbury (1981), who determined
the sticky pad method as being representative
of between 2 and 7 days of dust deposition. (Beaman
& Kingsbury ‘Assessment of Nuisance
from Deposited Particulates Using a Simple and
Inexpensive Measuring System’, Clean Air,
Vol.11, No. 2 pp77-81, 1981). The method
can be relatively non-intrusive which makes it
popular in areas where conspicuous monitoring
is likely to cause problems
Voelcker Consultants have
experience in undertaking projects using a number
of the methods outlined above.
The work normally takes
the form of an initial baseline survey of dust
conditions in an area and then surveying during
and after a project has been completed in order
to indicate whether activities result in an increase
in the levels of nuisance dust.
The input of clients is
essential in designing such investigations, please
feel free to
to discuss your needs.
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