Updated: Dec 7, 2020
For people working in bakeries, flour and ingredient dusts can cause a variety of health issues. When inhaled, airborne dust can cause rhinitis (running nose) and conjunctivitis (watering eyes and irritation) and more seriously, occupational asthma (breathlessness, chest tightness and wheezing).
In the UK, the legal standard for the control of exposure risk to flour and ingredient dust is contained in the Control of Substances Hazardous to Health Regulations 2002 (COSHH).
Assessing Dust Levels
Bakers’ Asthma is one of the most common forms of Occupational Asthma. Many different potential allergens are present in flour dust, such as cereal antigens and enzymes, particularly a-amylase.
Respiratory sensitisers or asthmagens are substances that may cause Occupational Asthma when inhaled. The hypersensitive state is a change in body's airways caused by these asthmagens. Not everyone who has become sensitised will begin to suffer from asthma, but if the lungs become hypersensitive, even low levels of further exposure could trigger attacks.
Cereal flours such as wheat flour, rye or barley are more commonly associated with cases of Occupational Asthma, but other flours such as soy and buck wheat have also been reported as sensitisers. Bakers’ Asthma caused by sesame seeds, eggs, yeast, and sunflower seeds could be a challenge with the trend moving to more seeded products.
An effective means of observing dust in the workplace is by shining a dust lamp on to a dust cloud, to allow easier identification of dust sources and assessment of control systems. Observing dust deposits on horizontal surfaces can also be a good indicator of escaping dust.
RCS's fully trained engineers can carry out a full site survey to determine sources of dust and provide options for potential LEV solutions, fully COSHH compliant and tailored to your needs.
Tasks where exposure to flour dusts and/or enzymes may include:
Filling mixers from bags
Dough brake roll machines
Disturbing hoppers containing flour by adding ingredients by hand
Breakdowns and Maintenance
Employers are required to be fully compliant to Control of Substances Hazardous to Health Regulations 2002 (COSHH). The long-term Workplace Exposure Limit (WEL) for flour dust has been set to 10mg/m3 (averaged over 8 hours) and short-term limit of 30mg/m3 (averaged over 15 minutes). The employee’s exposure to flour dust MUST be reduced to ‘as low as reasonably practical’ due to chronic health effects associated with it.
Reducing Exposure To Dust
Risk management measures should always be based on a hierarchy of controls.
Exposure should be prevented primarily through elimination or substitution of the hazard. In the event that this is impossible, controlling exposure by isolating or reducing the hazard through design or engineering means is the next most effective measure. Administrative controls may also be used, for example, the introduction of safe working practices/procedures. Minimising exposure through respiratory protective equipment(RPE) is the final measure in the hierarchy.
Consider the following controls for eliminating the risk of dust exposure:
Rice flour as lubrication or for hand dusting.
Non-stick surfaces, eliminating the need for dusting flour.
Using oil spray or in smaller bakeries, greaseproof paper.
The following controls can reduce airborne dust levels:
Alternative forms of ingredients such as flour treatment agents now available as a liquid, paste or granular forms.
Lubrication and hand dusting with low dust flour or rice flour.
Lubricating with oils.
- Bulk Flour Storage
Dust levels can be greatly reduced through the use of silos and associated closed conveying, weighing and dispensing equipment. Serious dust problems may however still be caused through silo overfilling and spillage.
- Bag Tipping
Bag tip units should be enclosed and fitted with Local Exhaust Ventilation (LEV). The bag should be rolled up from the bottom with the open end facing away from the operative towards the LEV.
- Sieving/Weighing of Powdered Ingredients
Effective LEV as well as operator RPE (min FFP3) should be used in situations where manual sieving/weighing is carried out for more than 30 minutes a shift excepting circumstances when the installed LEV is tested and proven to properly and effectively capture the dust to a level where RPE may not be needed for the task. Large walk-in laminar/downflow booths may be needed in the case of plant bakeries to allow containment of containers and scales.
- Mixer Filling
To contain dust when tipping bags directly into mixers, the bowl should be covered as much as possible, the mixer lid or purpose built cover should be used for this purpose. To prevent the escape of dust before liquid is added, mixer lids should be as tight fitting as possible. Effective LEV and suitable RPE (min FFP3) is required in circumstances where there is only a partial enclosure and when tipping more than 15 sacks per shift, excepting circumstances when the installed LEV is tested and proven to properly and effectively capture the dust to a level where RPE may not be needed for the task.
When filling mixers or bowls from a weigh hopper, the bowl must be sealed while loading and LEV provided to extract generated dust or a filtered outlet provided on the lid, allowing the displaced air to escape. When tipping dry ingredients by hand into high speed mixers in plant bakeries, the control measures required must be determined via a risk assessment. RPE must also be worn in cases where exposure levels may not be reduced to below 2 mg/m-3.
Dust prevention in large scale plants can also be achieved through the use of automatic closed conveying to the mixer.
What Can RCS Do For You
RCS's engineers will endeavour to provide you with the most effective and cost-efficient solution for flour dust extraction and filtration in partnership with Donaldson. Call us on +44(0)1563 546807 or click here to contact us for more information.