When blasting is done in a congested area or in close proximity to a building, structure, highway, vehicle, conveyance or any other installation that may be damaged by material being thrown into the air, the blast shall be covered with an adequate blasting mat or shield. Proof that any such building structure, highway, vehicle, conveyance or other installation was damaged to any degree by material which was so thrown into the air shall raise a rebuttable presumption that said blast was not covered with an adequate blasting mat or shield. For purposes of this section, an otherwise adequate blasting mat used improperly shall not be considered to be an adequate blasting mat or shield.