Horses and riders are exposed to irritating levels of dust that is lofted during activity in riding arenas. The riding surface, or footing material, is typically a soil-like or organic-based material. A study was conducted in two indoor horseback riding arenas where total and respirable dust was collected over three sampling periods via gravimetric methods. Gravimetric procedures necessitate humidity and static electricity control during weighing evaluations. Even with these precautions, redundant samplers are recommended. Dust was associated with the overall quality of the footing in the arena, with greater dust detected from the footing of lower moisture content with a greater percentage of fine particles (inorganic footing). Dust detection in the arenas was greater and more appropriate when calculated according to level of horse activity in a session. Total dust level was 0.612 mg/m 3 or 3.395 mg/m 3 (organic and inorganic footing, respectively) when calculated based on time arena was occupied by horses. Both dust levels were 2-1/2 to 3 times higher than this during times of horse activity faster than a walk. Respirable particles were 54 to 60% of the total dust during riding activity.