Layers of dust can typically form in the workplace from the manufacturing process, particularly if you handle bulk powders or remove waste pneumatically. Leaking equipment, seals, flexible connections, filter socks, general air movement from extraction/ventilation system can all be sources of fugitive dust. One particular risk from the accumulation of fugitive dust on high level structures, due to poor industrial hygiene is that it can act as a fuel for a secondary explosion.
Secondary dust explosions
An explosion event within a piece of plant can shake the building and release dust on high structures into the atmosphere within the workplace. Such a sudden release of explosive fuel (air and flammable powder mix) into low-risk zones without adequate ATEX equipment safeguards and other potential ignition sources is a receipt for disaster. A secondary explosion that is generally more destructive than the primary explosion.
Controlling dust layers
Controlling dust layers is a challenge common across many industries and should not be neglected. It is usually a continuous maintenance process designed to mitigate the risk to the plant through regular cleaning/removal. It should not be considered a one-off exercise undertaken when the levels become noticeable or intolerable as by that time you have already allowed the elements of the flash fire / explosion to be put in place.
The following are some considerations to assure housekeeping procedures meet safety requirements:
- Do not use cleaning methods (air jets) which disperse dust layers.
- Do not sweep up dust using brooms
- Use fixed vacuum cleaning systems and ensure they are explosion protected.
- Use portable vacuum cleaners that are ATEX certified or one that is suitable for the collection of combustible dusts.

Image and below case study courtesy of SpaceVac International
“Immediately after an incident the site hired our Atex REACH systems for a month in order to remove high level dust. Whilst the incident itself was not caused by this fugitive dust the site was lucky that they static explosion did not trigger a deflagration event, this was picked up by the inspectors and so our solution was employed to remove the risk. They then went on to purchase systems.”
DSEAR
Your DSEAR assessment should identify if you store or process flammable powders and where high-risk zones occur within the workplace. It will be observed on site inspection if fugitive dust is a potential hazard and what actions are routinely undertaken to mitigate this risk. Industrial hygiene on high surfaces is not an option but a necessity to ensure DSEAR compliance.
Reference guidance document
- UK HSE guidance document HSG-103 – freely available on the HSE website: https://www.hse.gov.uk/pubns/books/hsg103.htm
- UK HSE Guidance Prevention of dust explosions in the food industry – freely available on the HSE website: https://www.hse.gov.uk/food/dustexplosion.htm
- Solids Handling and Processing Association (SHAPA) – ATEX Compliance with Legislation and implementation (co authored by the UK HSE) – it is freely available on their website: https://shapa.co.uk/technical.php