Then what can we do, at home, if we don't want to buy a mask, will covering our mouths and noses in any cloth( say a bandana?) be just as effective?

See this link:http://news.yahoo.com/nphotos/surgical-mask-surgical-masks-University-of-Michigan-study-Ann-Arbor2C-Mich/photo//081028/480/679749549cbc49eab3ff51b6069a09b9//s:/ap/med_catching_colds;_ylt=AoTxWTeVHgjcE5VxzpN7dvBa24 cA