Objective To assess whether exposure can be reduced by providing feedback to the farmers concerning the levels of dust that they are daily exposed to in their farm.

Methods The personal dust levels of farmers in 53 pig and 25 dairy cattle farms were evaluated in 2 measurement series performed approximately 6 months apart. Detailed information on technical parameters and farm characteristics were also registered. Participating farms were a priory randomly divided into a control (n = 39) and an intervention group (n = 39). Shortly after the first visit, farm owners in the intervention group received a letter with information on the measured dust concentrations on their farm together with some general advises on exposure reduction strategies (e.g. use of respirators during certain tasks). Relationships between measured dust concentrations and intervention status were quantified by means of linear mixed effect analysis, with farm id as a random effect. Season, type of farming, visit, intervention status and their two-way interactions were tested as fixed effects.

Results After adjustment for season and farm type we found no effect by intervention status. There was no interaction by type of farm, but measured dust levels on the second visit were significantly lower than during the first visit. Similar results were observed in models stratified by type of farming, where the effects of visit were most clearly observed among pig farms.

Conclusion These preliminary findings suggest no interventional effects on the levels of exposure; though, the presence of the investigation itself seems to reduce the levels of exposure. By June 2013, the authors intend to present the above results along with those from further analysis addressing potential changes in working patterns and hygienic parameters during the second exposure evaluation.