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 compassThe 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 soiling 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.
SOCOTEC has 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.
Visit our air quality page to find out more