Objective To indentify working tasks which determine the level of personal exposure of dairy cattle farmers to inhalable dust and endotoxin.

Methods 124 personal full-shift inhalable dust measurements were performed in 77 farmers from 26 dairy operations. The concentration of collected dust on the samples was estimated gravimetrically and its endotoxin content by the kinetic chromogenic Limulus Amebocyte Lysate assay. During monitoring all tasks performed by the farmers were registered in self-administrated activity diaries, and walk-through surveys were performed in every compartment of the visited farm. Effects of working tasks on the log-transformed dust and endotoxin concentrations were examined in Linear mixed effects models. Worker and farm identity were treated as random effects, and working tasks as fixed effects.

Results Measured concentrations for inhalable dust ranged between 0.2 and 9.8 mg/m³ and for endotoxin between 17.6 and 5890 EU/m³. Preliminary models with 12 and 14 working tasks for endotoxin and dust respectively explained 27% and 23% of the overall variability in exposure. Preparation and spread of bedding, re-penning of animals and handling of feeding materials in storage areas were all strong predictors for both dust and endotoxin exposure. Decreased dust exposures were seen when cleaning of milking areas or reparation of buildings was performed. Robotic milking was associated with increased dust levels when compared to parlour milking.

Conclusion These initial findings provide information on working tasks that determine the level of personal exposure to dust and endotoxin during dairy farming. By June 2013, the authors intend to present results from statistical models which will examine the combined effects of farm characteristics and working tasks.