Use of continuous measurements of integral aerosol parameters to estimate particle surface area

While surface area is one of the most important atmospheric aerosol propert ies in health effects, methods for online measurement of surface area are n ot widely available and/or require complex operations. In this paper, me de scribe an integrated measurement method that can continuously monitor the t otal surface area. as well as the total number and volume, of atmospheric a erosols. Three integral aerosol sensors-(i) a condensation particle counter (CPC) for number concentration measurement, (ii) a mass concentration moni tor (MCM) for mass concentration measurement, and (iii) an electrical aeros ol detector (EAD) for current measurement of charged aerosol-are used in th is study, Signals from the three sensors are converted into a lognormal siz e distribution by minimizing the difference between the measured signals an d the theoretical values based upon a size distribution model, the instrume nt calibration, and its theoretical responses. Results from a 20 day contin uous sampling period show that the calculated total surface area from integ rated measurement correlates well with that of particle sizing measurement. The calculated lognormal size distribution parameters between the two meth ods have similar values, These results suggest that the integrated measurem ent method is feasible to continuously measure total number, surface area, and volume concentrations. iis the integrated measurement method can yield results in near real time, it can be used for online measurement of atmosph eric aerosols.