How dust can affect people, process and plant – Part 1 Health

How dust can affect people, process and plant – Part 1 Health

In a series of three articles, Finch looks at the use of powdered ingredients used in the food industry, and how if not controlled effectively, the dust from these can adversely affect people, processes and plant. In the first article, we look at people, and in particular health.



Written by

Morag McWilliam

As you would expect in the food industry many powdered ingredients are used on a routine basis, for example flours, sugars and spices.

Exposure to the dust from these ingredients can result in illnesses such as occupational asthma, rhinitis, conjunctivitis and dermatitis.

Occupational asthma is an allergic reaction that can occur in some people when they are exposed to dusts from substances such as wheat flour, some spices and flavourings, flour improvers, egg protein and fish protein. These substances are known as respiratory sensitisers or allergens.

Not everyone who is exposed to a respiratory sensitiser will develop asthma, but once the lungs become hypersensitve, further exposure to asthmagens, even very low levels, can trigger an asthma attack.

Exposure to dust from the materials such as those referenced above can cause allergic rhinitis (irritation of the nose causing symptoms similar to a cold) and allergic conjunctivitis (irritated, red and watery eyes).

In addition, exposure to dust from flour and other dry ingredients can cause irritant contact dermatitis. This is not an allergic reaction but can be caused by frequent exposure to weak irritants such as dust and powders. The dust and powders can damage the outer layers of skin which may lead to irritation, drying and cracking.

Dusty processes in food manufacturing include:

  • Bulk sieving of dry ingredients;
  • dispensing, weighing, tipping and transfer of dry ingredients;
  • use of ‘dough breaks’ (sometimes called a dough sheeter, used to roll dough and pastry to consistent thicknesses);
  • flour dusted onto work surfaces, conveyors and baking trays to prevent dough from sticking;
  • cleaning activities.


The Control of Substances Hazardous to Health Regulations 2002 (as amended) (COSHH) requires employers to prevent exposure to hazardous substances, or where it’s not possible to control it.

Because of the severity of disease that respiratory allergens such as flour dust may cause, the requirement to control exposure is more stringent than for other materials. Exposure to respiratory allergens must be controlled to a level as low as reasonably practicable, and not just below any relevant exposure limit. This is often referred to as control having to be ‘ALARP.’

COSHH also requires employers to apply the ‘Hierarchy of Control’ when determining which measures they will use to achieve ALARP.

This means that, in the first instance, they should eliminate exposure or consider substituting products for those less hazardous.

Since food production usually requires ingredients to go through stringent quality assurance and sometimes recipes are subject to registration with authorities, these first two options are often not possible, so the employer must focus their resources on engineering and administrative control measures to reduce employee exposure.

LEV Systems

Containment and Local Exhaust Ventilation (LEV) are the most commonly used forms of engineering control put in place to reduce exposure to dust in bakeries and other food manufacturing industries.

LEV systems vary depending on the nature of the dust generated and the process in which it occurs.

Generally, LEV systems are made up of some type of hood to capture the dust as it’s generated at the source, some ductwork to carry the dust away from the work area, an air cleaner such as a filter, an air mover such as a fan and a discharge point.

Depending on the complexity of your process you may need help to design an LEV system, but the following points will help to make sure your system is effective:

  • Try to enclose the system as much as possible, particularly where materials are charged, discharged, weighed and dispensed.
  • Fit the extraction point as close as possible to the point at which dust is generated or released.
  • Permanent dust extraction systems are preferable and usually more robust than portable ones, though these can be used.
  • Airflow must be sufficient to capture the dust and then transport it through the LEV system to the discharge point. This is especially critical where one LEV system has multiple branches.
  • LEV ductwork should be rigid rather than flexible, in short runs and avoid sharp bends, acute angles and other awkward shapes where entrained dust could drop out of the airflow and begin to block pipework and filters.
  • Fit airflow indicators such as Magnehelic gauges as an easy way to check that the system has been switched on and is working as designed, and an alarm to show if filters are blocked or have failed.
  • Use viewports to lessen the need to open vessels which may release dust.
  • Ensure a good standard of general ventilation, and if possible, ensure that you site production work away from doors, windows and walkways to avoid draughts from these interfering with LEV and spreading the dust.
  • Ensure LEV systems undergo Thorough Examination and Testing (TExT) as required by COSHH regulations every fourteen months or more frequently depending on the process.
  • Consider ATEX requirements considered in this article of the LEV system if the dust can create a potentially explosive atmosphere.


Your colleagues, particularly those who are involved in production will be able to help identify work practices which may result in reduced dust generation, so it’s important they are included when you are trying to identify practical measures to introduce on your site. Engaging with the people who will work with LEV at the point of dust control can lead to improved design and greater acceptance.

You could consider the following:

  • Where practicable, buy in pre-weighed amounts of dry ingredients which will reduce the amount of weighing required.
  • Investigate whether or not spices, flavourings and enzyme improvers are available in liquid or paste form instead of powdered.
  • Avoid hand throwing of flour as much as possible. If flour must be used as a lubricant to stop dough etc sticking to work surfaces, consider using low dust flour and dispense from a lidded flour dredger fitted with an agitator to minimise dredger blocking.
  • Consider using a light coating of food-grade oil on surfaces to remove the need to use flour as a lubricant.
  • Use solid lids on mixing vessels wherever possible, and charge all ingredients including liquids slowly, and from as low a height as possible.
  • Start mixers slowly.
  • Clean up using an industrial vacuum cleaner which should be at least an  ‘M’ classification and fitted with at least two filters in series to minimise the risk of dust passing through to the motor.
  • (Depending on the dust being handled, you may also need to consider whether or not your vacuum cleaner should be Ex-rated under the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR))
  • Damp wiping and wet mopping may also be used, but dry sweeping of dust should be avoided.

In controlling your employees’ exposure to dust, particularly if control has to be ALARP, it is likely that you will have to use a combination of the above engineering and administrative controls coupled with giving your employees sufficient information, instruction and training on how to use them.

What about PPE?

These controls may still not be enough, and you will then have to consider the use of suitable Personal Protective Equipment (PPE).

In the hierarchy of controls, PPE is used as a last resort, since it protects only the person wearing it, and if they are not wearing it correctly or all the time, protection will be insufficient.

Any PPE should be selected on the basis of risk assessments of employees’ exposure to dust.

This is especially important for Respiratory Protective Equipment (RPE).

RPE as a control measure is a broad topic which includes the selection, use, maintenance and management of devices, and therefore it will be covered at a later date.

If you would like further information on the topics covered above, or other aspects of occupational hygiene or health and safety in general, please do not hesitate to contact Finch Consulting’s experts.

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