Contents: Fuchs, N. A. Aerosol impactors (a review)--Mercer, T. T. Brownian coagulation: experimental methods and results.--Davies, C. N. Evaporation of airborne droplets.--Kirsch, A. A. and Stechkina, I. B. The theory of aerosol filtration with fibrous filters.--Spurny, K. R., Centry, J. W., and Stöber, W. Sampling and analysis of fibrous aerosol particles.--Pich, J. Theory of electrostatic mechanism of aerosol filtration