The demands for space where horses are kept should be adapted to optimal conditions that meet the requirements of their welfare. Employees handling these animals spend a significant part of the day there. In order to assess air dustiness, research was carried out on a farm keeping mares for milk production. The research was performed on a farm keeping 30 cold-blooded horses in autumn. The monitoring covered dust PM1, PM2.5, PM10, respirable dust and total dust. Measurements were made in 3 different kinds of space: a stable with foals, a stable with mares, and a room to milk the mares. The highest concentration of total dust (5.37 mg/m3) and respirable dust (1.17 mg/m3) was obtained in the room with foals, and the lowest in the mares stable (0.55 mg/m3 and 0.31 mg/m3, respectively).