The efficiency of cellulose fibre filters with respect to lead and black smoke in urban aerosol

Abstract Retention efficiencies have been empirically determined of three types of cellulose filter which have been widely used for sampling urban aerosol (Whatman Nos. 1. 4, and 541). Clean papers retained approx. 50, 30 and 15 per cent of lead, and 70, 40 and 30 per cent of “black smoke” respectively, at a face velocity of 6.5 cm s −1 . In each case, retention efficiency approached 100 per cent at a soiling value (100 — per cent Reflectance) of 40 per cent.