Rida Al-Horr

Measurement of Both Nonvolatile and Semi-Volatile Fractions of Fine Particulate Matter in Fresno, CA

An intensive sampling campaign was performed in Fresno, CA during December 2003 measuring fine particulate matter including both the semi-volatile and nonvolatile fractions of the aerosol. Both the newly developed R&P FDMS Monitor and a PC-BOSS have been shown to measure total PM 2.5 concentrations including semi-volatile nitrate and organic material. Good agreement was observed between the PC-BOSS and the R&P FDMS Monitor in this study with linear regression analysis resulting in a zero-intercept slope of 1.00 ± 0.02 and an R 2 = 0.93. Several real-time measuring systems including the R&P Differential TEOM, the Met One BAMS, and a GRIMM Monitor were also employed and comparisons of total PM 2.5 mass were made with the R&P FDMS Monitor. Agreement among these various monitors was generally good. However, differences were sometimes seen. Reasons for observed differences in the real-time mass measurement systems are explained by the composition and complexity of the measured aerosol, most importantly the composition of semi-volatile material. A newly automated ion chromatographic system developed by Dionex was also field tested and compared to both R&P 8400N Nitrate and integrated PC-BOSS inorganic species measurements. Sulfate and nitrate determined by the Dionex and PC-BOSS systems agreed. However, nitrate measured by the 8400N was low during fog events compared to the other two systems.

Monitoring and Source Apportionment of Fine Particulate Matter at Lindon, Utah

Under the EPA Science to Achieve Results (STAR) and the Environmental Monitoring for Public Access and Community Tracking (EMPACT) programs an intensive sampling campaign was performed during the month of August 2002 at the state of Utah Air Quality monitoring site in Lindon, Utah. The concentrations and composition of PM2.5 were measured using a variety of continuous samplers including a TEOM monitor to measure non-volatile PM2.5, a RAMS monitor to measure total PM2.5 including semi-volatile species, an ion-chromatographic based instrument to measure sulfate and nitrate, and an Anderson Aethalometer to measure elemental carbon and UV adsorption. Integrated PM2.5 data were collected using a PC-BOSS sampler, for the determination of detailed particle composition. Continuous gas phase concentrations of NO, NO2, NOx, H2O2, and O3 were also monitored. One-hour average PM2.5 data have been combined with continuous gas phase data to perform source apportionment using the EPA UNMIX program. Sources of fine particulate matter were apportioned into primary emission sources and secondary formation processes. Identified were primary mobile sources, including diesel and gasoline combustion vehicles, and both a day-time and night-time secondary source.

In-line monitoring of acid and base contaminants at low ppt levels for 193nm lithography

In this paper, a technique for in-line monitoring of acid and base contamination is described. The technique is applied to purge gas monitoring and the air at the in- and outlet of the active charcoal filters on an ASML PAS5500/1100 193nm scanner is analyzed. Unparalleled lower detection limits (LDL) were obtained, especially for acid detection, where LDLs below 10ppt for SOx were achieved. At the inlet high contamination levels (0.5-3ppb) of NO/HONO and SOx are detected. The filters effectively remove the SOx contamination. The residual SOx contamination could be measured and the average was found to be ~2ppt, corresponding to a filtering efficiency of 99.8%. The filtering efficiency for NO and HONO is significantly lower and was found to be ~98%, which is in agreement with previous reports.1