Patented recently is an invention that relates to a spun-bonded nonwoven fabric made of polyolefin filaments having a titer<1.6 dtex, the spun-bonded nonwoven fabric having a basis weight.ltoreq.18 g/m.sup.2, a waterproofness of <15 cm measured as a water column. In addition, it has an air permeability of at least 230 m.sup.3/(m.sup.2min), wherein the product of the air permeability and the basis weight is .ltoreq.5000 g/(mmin).