Abstract An in-depth comparative study was conducted to define the relationships between and among commonly used methods for measuring suspended particulate matter. High volume air samplers, British smokeshade measuring devices, membrane filter samplers, tape samplers, and cascade impactor samplers were operated for 24-h sampling periods at 11 sites in Great Britain from January to June 1970. Data derived from gravimetric and optical analysis of the samples were used to develop regression equations and other relationships. Smokeshade measurements generally were lower than the corresponding hi-vol measurements when concentrations of suspended particulate matter were low. In contrast, black staining particulate matter can result in smokeshade values higher than corresponding values obtained gravimetrically. The soiling index correlated poorly with gravimetric measurements of suspended particulate matter. Size distributions and other parameters are discussed.