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Are we measuring construction dust or ambient dust levels?

15 August 2017

It is now common practice to monitor dust levels in the vicinity of demolition and construction sites.  This is to ensure dust emissions are not at a level which could be hazardous to health for those working on or living close to an active project. Modern monitors can provide accurate dust data in real time and alert project managers immediately of high levels of dust so they can take the required actions.

Dust definitions:

 

What is dust?

According to British and International standards  BS 6069: Part 2 1983, ISO 4225-1994 – Characterisation of air quality dust is defined as follows:

Defines dust as being “particles less than 75 micrometres” in diameter

What is PM10?

PM10 are particles suspended in the air which are smaller than 10µm in diameter.

Particles larger than 10µm in diameter (PM10) are often referred to as a nuisance rather than a health risk.  They are too large to penetrate the respiratory tract and not considered so dangerous to health.  We therefore usually measure PM10

 

Sources of PM10

The sources contributing to PM10 are numerous and include activities from transport, industry, agricultural, power generation and many more.

World health Organisation (WHO) recommend limits of PM10 as 20 µg/m3 as an annual mean and 50 µg/m3  as a 24hour mean.

Below is plotted an hourly average for a dust monitor in a central London location for February 2017.  The monitor is located on the perimeter of a construction site to measure dust emissions.  

In mid February levels can be seen to be on or close to WHO mean limit levels for a 24 Hour period. In such instances it is useful to compare data from other sources to see if the measured levels are from construction sources or general ambient PM10 values.

On the above project it was possible to compare with identical Aeroqual Dust Sentry monitors the levels for the same period.  Below is the same period plotted for 10 dust monitors located in different parts of central London.  It can be seen that there is a very strong correlation in the data indicating that the increased levels are part of an ambient trend in PM10 levels for London over this period.

The dust monitor data which is indicated below is typical of dust from demolition and construction sites. 

This is where you see short term spikes in PM10 levels which are localised.  This is why you will often see short term limits over a 15 minute period set by controlling bodies.  Short term limits are often set in the region of 150 to 250 µg/m3 to help control these dust events.

 

If you have access to other dust monitors in the vicinity it is useful to compare data. Defra and londonair.org.uk also publish data online from their various permanent air quality stations which includes PM10 levels.

 

Campbell Associates supply dust monitoring equipment for sale and hire

http://www.campbell-associates.co.uk/category/dust-monitoring

 

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