Air-pollution filter and face mask

A filter which has a plurality of component elements which, in combination, provide means capable of passing a gas stream therethrough at a flow rate which, per circular section of about 5 centimeters in diameter, is in the range of from 50 .+-. 20 liters per minute at a pressure drop of at most about 4.0 centimeters of water, the elements comprising, in sequence:

• i. porous compressible means to filter contaminated gas and particulate activated charcoal means;
• ii. low-resistant prefilter means to retain particles and to protect subsequent elements;
• iii. low-resistant filter means for filtering particulate matter as small as 0.3 micron in diameter and moisture-trapping absorbent means;
• and
• iv. means to protect preceding elements;
• the particulate activated charcoal means being no further upstream than the porous compressible means;
• the moisture-trapping absorbent means being no further upstream than the low-resistant filter means;
• the porous compressible means providing means for removal of large dust particles, pollen grains, other particulate matter and aerosol droplets from the gas stream;
• the particulate activated carbon means providing means for removal of irritating gases from the gas stream;
• each element being immediately juxtaposed to adjacent elements;
• and the porous compressible means exerting sufficient positive pressure to maintain the particulate activated charcoal means in position.