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Construction dust: Chasing concrete and raking mortar

Chasing concrete and raking mortar can produce very high levels of silica containing dust. Effective control is necessary because this work is high risk. This page tells you how to control the risk and why. You also need to be aware of the general information on construction dust.

What you must do

Follow the Assess, Control and Review model. Pay particular attention to the following things:

Assess

Identify and assess: Chasing concrete and raking mortar can produce very high levels of silica containing dust. Anyone breathing in this dust cloud will be affected. Those using or very close to the grinder etc. will be particularly at risk. Follow the control steps below.

Control

Prevent: Think about limiting the risks before work starts by:

Control: Even if you minimise some of the dust this way, you may still need to do this work. Control the risk by:

Review

What you should know

When uncontrolled both tasks quickly produce very high levels of silica containing dust. Watch the graph in the video clip below. The Workplace Exposure Limit for silica is 0.1 mg/m3 when averaged over 8 hours. The work quickly produces very high peak exposures of around 5 mg/m3.

Uncontrolled dust chasing video. To view this media, please turn on Javascript.

Now watch the video below. The graph shows a dramatic drop in the amount of silica when using extraction. It is important to note that the extraction does not capture all of the silica. RPE is also needed as a back up measure. It protects against this remaining level of unknown and variable silica risk. It also protects against high exposures caused accidentally by the worker or a fault with the extraction.

Controlled dust chasing video. To view this media, please turn on Javascript.
Updated 2014-09-11