An air filtering device comprising: a base having an air inlet and an air outlet; a fan functionally attached to said base, wherein said fan moves about 85 m 3 /h to about 255 m 3 /h (about 50 CFM to about 150 CFM) of air through said air outlet with a total pressure drop within said device of about 4 to about 25 Pa and with a sound power between 35 and 50 dB(A)when said fan is activated; an air filter in air flow communication with said air outlet, wherein said air filter comprises a non-woven having a thickness between about 1 and about 3 mm, a density from about 20 kg/m 3 to about 60 kg/m 3 , and a pore volume distribution of at least about 15% of the total volume is in pores of radii less than about 50 μm, at least 40% of the total volume is in pores of radii less between about 50 μm and about 100 μm, and at least 10% of the total volume is in pores of radii less greater than about 200 μm, wherein said air filter has an initial pressure drop less than about 15 Pa at 9.1 m/min (30 feet/min) face velocity; a substantially air impermeable outer sleeve comprising a first open end, a second open end, and an air flow path therebetween, wherein said outer sleeve is in air flow communication with said air outlet and is releasably attached to said base at said first open end, and wherein said outer sleeve envelops said air filter around its longitudinal axis, wherein substantially air impermeable means the volume of air exiting the outer sleeve at the second open end is at least about 60% of the air entering the outer sleeve at the first open end when the device is in use; wherein the exit velocity of a volume of air exiting said second open end of said outer sleeve is about 0.5 m/s to about 3.0 m/s when said device is activated. a base having an air inlet and an air outlet; a fan functionally attached to said base, wherein said fan moves about 85 m 3 /h to about 255 m 3 /h (about 50 CFM to about 150 CFM) of air through said air outlet with a total pressure drop within said device of about 4 to about 25 Pa and with a sound power between 35 and 50 dB(A)when said fan is activated; an air filter in air flow communication with said air outlet, wherein said air filter comprises a non-woven having a thickness between about 1 and about 3 mm, a density from about 20 kg/m 3 to about 60 kg/m 3 , and a pore volume distribution of at least about 15% of the total volume is in pores of radii less than about 50 μm, at least 40% of the total volume is in pores of radii less between about 50 μm and about 100 μm, and at least 10% of the total volume is in pores of radii less greater than about 200 μm, wherein said air filter has an initial pressure drop less than about 15 Pa at 9.1 m/min (30 feet/min) face velocity; a substantially air impermeable outer sleeve comprising a first open end, a second open end, and an air flow path therebetween, wherein said outer sleeve is in air flow communication with said air outlet and is releasably attached to said base at said first open end, and wherein said outer sleeve envelops said air filter around its longitudinal axis, wherein substantially air impermeable means the volume of air exiting the outer sleeve at the second open end is at least about 60% of the air entering the outer sleeve at the first open end when the device is in use; <EOS>