A mat for reducing the disturbance of particulate matter by wind, has a first layer of coarse mesh material, and a second layer of coarse mesh material. The first layer is held in a substantially fixed position relative to the second layer. The mat is particularly suitable for use as a helicopter landing mat, in conditions where dust, sand, snow, water or other particles or liquids might otherwise cause a disturbance resulting in loss of visibility, damage or wear to parts of the helicopter, and injury or damage to nearby people or equipment.