Laboratory study of the effectiveness of substituting traditional wheat flour with low dust flour and use of different sieve designs as controls to reduce exposure to inhalable flour dust in commercial bakeries.

Abstract

Exposure to flour dust remains one of the leading causes of occupational asthma in Great Britain (GB). The average annual incidence rate per 100,000 bakers and flour confectioners in GB was 47.8 for the 3 yr period 2017 to 2019 compared with 0.53 for all occupations. There are many processes in commercial bakeries that can cause exposure to flour dust. Exposures are typically controlled by using local exhaust ventilation or respiratory protective equipment. The aim of this study was to evaluate the potential to reduce exposure to inhalable flour dust in commercial bakeries by modification of the process by use of a conical sieve in place of a round sieve; and substitution of traditional wheat flour (TWF) with 'low dust' flours LD1 and LD2 for dusting surfaces. Two simulated commercial bakery tasks were performed in a laboratory whilst dust exposures were measured in the breathing zone of the operator using an Institute of Occupational Medicine (IOM) sampler, button sampler and a real-time direct reading monitor. Analysis of variance tests were used to assess whether differences in mean exposures were statistically significant with the different control approaches. A qualitative visual exposure assessment was also undertaken using Tyndall illumination. Substituting TWF with LD1 and LD2 reduced exposure to inhalable flour dust by 86% and 53% respectively when sieving and by 78% and 67% respectively when filling a hopper. There was no statistically significant difference between dust emissions for all 3 flours when using the conical sieve instead of the round sieve for flour dusting tasks. This laboratory study has shown that substituting TWF with low-dust flour may reduce inhalable dust exposures when dusting surfaces in bakeries.