| Increases in ambient particulate matters (PM) concentrations are associated with adverse health effects. To test hypotheses regarding effects of atmospheric PM, it is essential to measure these particle properties accurately and efficiently. In this study, innovative methods were developed to measure properties of atmospheric fine particles, including ultrafine particles. An atmospheric fine particle measurement system was developed to measure aerosol size distribution from 3 nm to 2 μm in diameter. The peculiarity of this system is its high resolution in ultrafine particle size range, where only limited size distribution data are available. The system was used to measure aerosol size distribution in Atlanta, GA, at intervals of 12-minutes continuously for 25 months. We have identified three types of “ultrafine particle” events, which occurred only occasionally and are often characterized by unusually high concentrations of small particles. Depending on the location of the observed peak diameter, we labeled these “ultrafine particle” events as 3–10 nm, 10–35 nm and 35–45 nm events.; A sampling system, which utilizes the integral aerosol parameters measurement (IAPM) method, was developed to determine the total surface area of atmospheric aerosols. Signals from three aerosol sensors are converted into parameters of a lognormal size distribution function by minimizing the difference between the measured signals and the theoretical values based upon instrument calibrations and its theoretical responses. Results from a 20-day continuous sampling period show that the calculated total surface area from the IAPM correlates well with that determined from the particle size distribution measurement.; A “universal” distribution transformation (UDT) was developed to estimate moments of the aerosol size distributions. We showed that the UDT estimates high order moment (3rd or 4th) quite well, but estimates poorly for low order moment (0th or 1st).; A relative humidity (RH) conditioner was also developed in this study. The heart of the developed RH conditioner is a semi-permeable Nafion membrane, which serves as a counter-current water vapor exchanger. Field study results show that the RH conditioner has successfully maintained the RH of the sampled aerosol at ±2% absolute difference from the 40% set point for inlet RH ranging from 26.5% to 99.9%. |
