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Effectiveness of interventions to reduce flour dust exposures in supermarket bakeries in South Africa
  1. Roslynn Baatjies1,2,
  2. Tim Meijster3,
  3. Dick Heederik3,
  4. Ingrid Sander4,
  5. Mohamed F Jeebhay2
  1. 1Department of Environmental and Occupational Studies, Faculty of Applied Sciences, Cape Peninsula University of Technology, Cape Town, South Africa
  2. 2Centre for Occupational and Environmental Health Research, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa
  3. 3Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
  4. 4Institute for Prevention and Occupational Medicine of the German Social Accident Insurance (IPA), Ruhr-University Bochum, Germany, Germany
  1. Correspondence to Professor Mohamed F Jeebhay, Centre for Occupational and Environmental Health Research, School of Public Health and Family Medicine, University of Cape Town, Room 4.47, Fourth Level, Falmouth Building, Anzio Road, Observatory, Cape Town 7925, South Africa; mailto:Mohamed.Jeebhay{at}


Rationale A recent study of supermarket bakery workers in South Africa demonstrated that 25% of workers were sensitised to flour allergens and 13% had baker's asthma. Evidence on exposure reduction strategies using specifically designed interventions aimed at reducing the risk of baker's asthma is scarce.

Objectives The aim of this study was to evaluate the effectiveness of different control measures to reduce airborne flour dust exposure using a randomised design.

Methods A group-randomised study design was used to assign 30 bakeries of a large supermarket chain store to two intervention groups and a control group, of which 15 bakeries were studied. Full-shift environmental personal samples were used to characterise exposure to flour dust and wheat and rye allergens levels pre-intervention (n=176) and post-intervention (n=208).

Results The overall intervention effect revealed a 50% decrease in mean flour dust, wheat and rye allergen exposure. The reduction in exposure was highest for managers (67%) and bakers (47%), and lowest for counterhands (23%). For bakers, the greatest reduction in flour dust was associated with control measures such as the use of the mixer lid (67%), divider oil (63%) or focused training (54%). However, the greatest reduction (80%) was observed when using a combination of all control measures.

Conclusions A specially designed intervention strategy reduced both flour dust and allergen levels. Best results were observed when combining both engineering controls and training. Further studies will investigate the long-term health impact of these interventions on reducing the disease burden among this group of bakers.

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