Dust Exposure in Flour Milling and Bakeries: Occupational Hygiene Challenges in the Workplace

Written by Rachel Powis MSc CertOH LFOH – Occupational Hygiene Technical Manager (Envirochem)
Edited by Dr Alexander Bianchi CFFOH, FRSPH, DipOH, CChem, MRSC Scientific Advisor

The adverse health effects of flour dust exposure have been known at least as far back as
the 1700s, when flour millers’ lung was documented by Bernardo Ramazzini, a Florentine
physician. Since then, various research and exposure studies have been conducted to try
to better understand the impact of flour dust on the human respiratory system, and to get
to grips with its effect on the overall health of workers in the milling and baking industry.

It was specifically in the 1930s that allergic responses to flour dust were extensively
examined in bakers, when conditions such as “Baker’s Lung” were highlighted. In addition,
the observation of skin (i.e. dermal) responses to dust exposure in tandem with respiratory
(asthma) symptoms observed within cohorts of bakery workers added to existing evidence
of its potential as a sensitiser. Moreover, when bakery workers showed an absence of
symptoms following time off work away from the bakery, the link between flour dust
exposure and health effects was significant. Remarkably, even now in the early part of the
21st century, flour dust exposure remains a leading cause of respiratory disease. For
example, in 2021, it was cited by the UK SWORD reporting scheme (i.e. Surveillance of Work Related and Occupational Respiratory Disease) as a leading cause of newly reported
respiratory disease, second only to asbestos.

Occupational exposure to flour dust is commonly associated with a wide range of
respiratory ill-health conditions. Rhinitis is a common complaint as well as a “marker
symptom”, and typically precedes the more severe asthma and chronic bronchitis
symptoms associated with “Baker’s Lung”. At a deeper level, these health effects are
influenced by various factors such as the type of flour, the dose, duration of exposure,
individual responses and susceptibility, and the occupationally determined environmental

Numerous studies suggest that ill-health responses are indeed more complex than simply
reactions to flour dust itself; in addition to flour, enzymes – often used within improvers –
and allergens – such as Aspergillus fungi – contribute to respiratory sensitisation and
symptoms. The risk can be particularly high during the milling process due to the high
volume of flour handled and additional risk factors from co-associated biological agents
within with the raw materials undergoing processing. Furthermore, these can be
encountered during a range of bakery tasks, from manual hopper additions to sieving and
surface dusting, and tied to flour handling and agitation processes which in turn create
airborne dusts. Therefore, the prioritisation of occupational hygiene exposure control
measures throughout the industry remains vitally important to minimise workers’ exposure
and mitigate a range of potential health effects associated with the consequent risk of
serious respiratory and skin diseases.

Most occupational exposure limits for flour dust are set as “Inhalable dust”, and 8-hour TWA
(Time-Weighted Average) exposure limits vary significantly from the ACGIH (American
Conference of Governmental Industrial Hygienists) TLV (Threshold Limit Value) of 0.5
mg.m-3 to the UK’s Health and Safety Executive WEL (Workplace Exposure Limit) of 10
mg.m-3. However, the literature records that ill-health effects have been reported at
exposures occurring below 0.5 mg.m-3 in some instances, indicating that first order
compliance with set occupational exposure limits may not in of itself be adequately
protective of health. Importantly, it underscores the critical significance of controlling
exposure to flour dust in the workplace as far as possible through application of ‘good
practice’ hygiene controls and associated measures.

The concept is not a new one; indeed, it is central to the ‘control and reduce’ philosophy of
the UK COSHH regulations, whereby emphasis on driving down exposures to as low as
reasonably practicable (and in real terms, meaningfully below applicable exposure limits)
applies for all forms of occupational sensitisers – for which flour dust most certainly has
been identified as. Consequently, it is crucial for flour milling and bakery facilities to
prioritise their occupational hygiene measures such as to minimise dust exposure. This is
essential to both protect their workers’ health and demonstrate sustainable and viable
compliance with regulations. Such occupational hygiene interventions include the initial
identification and recognition of all the key hazards and risks within the workplace followed
by thorough evaluation and monitoring of exposure levels. Moreover, above all, it requires
the full implementation of suitable and sufficient control measureswhich can offer genuine
and reliable long-term protection to all potentially-exposed workers.

Despite the inherent limitations with workplace sampling for direct comparison against
occupational exposure limits for flour dust (i.e. from a standpoint of health protection), the
effective and timely monitoring of air quality and dust levels in the milling and bakery
facilities is essential. How else can we understand exposure and identify any areas that may
require additional attention or improvement? Monitoring is an excellent tool for ongoing
exposure performance assessment and properly applied should drive ongoing commitment
towards continuous improvement.

Through such an approach the industry can gain insights to help create safer and healthier
environments for bakery workers, ultimately reducing the risk of serious occupational
health issues associated with flour dust exposure. In practical terms, HSE guidance suggests
that exposures of below 2 mg.m-3 (as an 8-hr TWA) should be reasonably achievable in any
case within bakeries when they apply good practice controls with exposure reduction
measures in place. However, this may be assumed or misapplied as a proxy exposure limit
or target level of exposure, and to that extent the HSE caution that meeting this level of
exposure may not in itself be indicative that good practice is in place. The guidance is clear;
the industry must demonstrate competence and capability in pushing exposure as low as is

Within many bakeries today, recent technological developments such as specialist “lowdust” flours have been explored largely to help achieve significant improvements for
reducing worker exposure. A 2023 study suggested an exposure reduction of up to 86%
during sieving was achievable; however, as a word of note, the composition of low dust
flours may render them unsuitable for specific applications and often comes with higher

Nonetheless, the implementation of effective dust control measures does not have to be
overly complex and costly. Simple control measures, such as reducing the amount of flour
used for dredging and placing lids on mixers can make large reductions in dust exposure
throughout bakeries. Similarly, sleeves surrounding transportation ducting, coupled with a
robust programme of equipment maintenance, have been assessed to significantly reduce
exposure for millers.

These measures, paired with regular competency training and the targeted use of personal
protective equipment for peak exposure tasks that cannot be avoided, form the backbone
of a successful programme for reducing occupational exposure. Importantly, the success
of control strategies is also often reliant onworker “buy in” and desirable behaviours, which
have a profound effect on individual exposures. For example, many cleaning activities still
rely on ‘high-dust generating’ dry sweeping which can lead to excessive exposures during
clean-up work and, frustratingly, undermine efforts targeted on control within routine
processes. The widespread use of archaic dry sweeping methods is possibly due to a lack of
awareness about best practices or oversight from employers and employees alike.
Therefore, training and education programs should always be implemented at the same
time across all levels within organisations. Effective control emphasises e3nsuring that
workers are aware of the health risks associated with flour dust and are equipped with the
knowledge and skills (and equipment) to minimise their exposure.

Awareness, however, is not the only barrier to effective control. Although commonly seen
throughout bakery facilities, air extraction fitted with moveable capture hoods are often
not well suited to manage sieving or surface dusting as they depend heavily on appropriate
positioning, which can be difficult to achieve. Alternative enclosure-type extractions
generally offer better control and have an advantage of not being dependant on user or
physical and area restrictions. Identifying suitable controls, therefore, involves both
technical and user input to find options which are suited both to the process and

Not least, worker health surveillance makes up an important component in overall
management of exposures by facilitating early detection of any individual potential health
effects on workers. Regular health surveillance should be conducted for workers in flour
milling facilities to monitor and identify any respiratory and skin symptoms or diseases that
may be linked to flour exposure. Health surveillance also plays a vital role in helping with
early intervention and treatment, as well as supporting occupational hygiene in assessing
the effectiveness of control measures in place. From a broader perspective, regular reviews
and information sharing between occupational hygiene and health professions is
advocated to fully understand ill-health risks and make targeted control interventions
where needed.

Envirochem has considerable expertise in occupational hygiene matters with respect to
dust, noise, and manual handling across a multitude of industries including the food sector.
We are passionate about creating better health outcomes for your personnel, who in turn
will create better outcomes for your business. Our goal is to help you build a healthier and
more productive business through our expertise in Human Health & Environmental testing
& consultancy.

Our specialists work as trusted advisors, supporting and assisting clients directly, whether
scoping occupational hygiene dust monitoring and consultancy, or noise assessments or
asbestos sampling. Supporting beyond the level of initial scope, we help clients identify
other potential sources of health exposure risk which also may require due consideration, spanning from noise and vibration hazards to dust explosions and DSEAR. Envirochem is
your extended team when it comes to making your people safer.

Our occupational hygiene monitoring programs can provide you with useful baseline data
across your operations. This only takes you so far on your safety journey towards best
practice. We are committed to assist you in making quality, continuous improvements in
worker health with real-world actionable steps which facilitate the positive changes that
are required. Envirochem can provide expertise and advice, tailored to your specific needs
and site requirements, through bespoke control audits. The worker exposure data we
collect will be used in conjunction with our consultancy experience, to help determine what
you can do to effect the changes you need to make.

For a free site scoping meeting, please contact us in confidence at: john.stead@envirochem.co.uk

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