Measurement of Aerosol Absorption Coefficient from Teflon Filters Using Integrating Plate and Integrating Sphere Techniques

Abstract

Optical transmission of aerosol samples collected on Teflon filters measured by the integrating plate method (IPM) has been used as a means of determining the aerosol absorption coefficient, b ap, by the Air Quality Group at Crocker Nuclear Lab for over 9 years. The results of an intensive quality assurance program, using an integrating sphere photometer configured for measurement of the transmission of filters, demonstrate that the IPM is highly precise (±1%) and does not suffer from inherent overestimation of particle absorption due to internal scattering, a problem commonly attributed to IPM measurements of aerosols collected on Nuclepore filters. If the appropriate correction is applied when filter loading exceeds a monolayer of particles, b ap can be accurately determined by the IPM for aerosol samples collected on Teflon filters.