What is the acceptable dust level in the place of horses’ maintenance?
There is considerable evidence promoting keeping horses at pasture. (McGreevy et al. 1995, and Hartmann et al. 2012) However, from a practical point of view, this not always possible with performance horses. Training schedules, competitions, space constraints, biosecurity and fear of injury mean that maintaining horses at pasture is not always feasible therefore the risk of inhalable particles to performance horses needs to be carefully managed in their housing.
In stabling, mean respirable dust content (RDC) should not exceed a maximum of 0.23mg/m³, however, mean RDC values as high as 2.5-3.0mg/m³ in stables have been found(Cargill,1999). The recommended total dust levels (RDC and non-respirable dust) in animal housing vary, from sources with Fiedorowicz (2007) recommending 3mg/m³, while Robinson and Sprayberry (2015), recommend 0.5 -1mg/m³ and recognize levels of dust above 2mg/m³ as too high. Published precise recommendations regarding allowable environmental exposure in equine housing do not exist currently, nor has a recognized threshold that has been associated with airway disease in the horse been published.