Measurements of Fine Particle Mass Concentrations Using Continuous and Integrated Monitors in Eastern US Cities

PM_2.5 mass concentrations were measured using multiple continuous samplers (a continuous ambient mass monitor (CAMM), a real–time ambient mass sampler (RAMS), and a drier–equipped tapered element oscillating microbalance (TEOM)) as well as a federal reference method (FRM) filter sampler in three eastern US cities. The effects of measurement systems, ambient conditions, and composition on the measured PM_2.5 mass concentrations were examined at each site. Different responses to PM_2.5 mass were observed by the continuous samplers with a variation of 10–30% in the average PM mass concentrations. The impacts of semivolatile particulate ammonium nitrate on PM_2.5 mass concentration was apparent for those time periods when high nitrate concentration >1.62 g m⁻³ was measured in Atlanta. Contribution of semivolatile particulate ammonium nitrate to the ambient PM_2.5 mass appeared more significant than semivolatile organic material in Atlanta. The effects of the ambient water were not negligible and were significant in Baltimore. The total ambient PM_2.5 mass by the CAMM was underestimated in all locations compared to the other continuous PM mass monitors, presumably due to the lack of equipments that collect semivolatile particulate ammonium nitrate and organic materials. The results suggest that short time intervals do not guarantee the measurement of total ambient PM_2.5 mass including semivolatile materials. In the comparison of each of the continuous versus integrated PM_2.5 mass over the sites, the drier–equipped TEOM presented the best agreement, with the FRM having r² values >0.90 and slopes close to 1 regardless of location and time period, suggesting that the same losses of semivolatile materials as seen in the FRM can occur in the sampling by the drier–equipped TEOM. The regressions between the CAMM or the RAMS and the FRM showed the variance of their relation, by site and time period, from 0.6 to 0.9 for r² and from 0.7 to 1.0 for the slope.

Acknowledgments

The United States Environmental Protection Agency, through its Office of Research and Development, supported and collaborated in this work under cooperative agreement CR827591. The authors greatly appreciate access to the field measurement data from James Sullivan (Harvard University). The use of the TEOM (Rupprecht and Patashnick Co.) and CAMM (Thermo Electron Corp.) do not constitute endorsement or recommendation for use. The views expressed in this article are those of the authors and do not necessarily reflect the views and policies of the USEPA.

Notes

^a The RAMS in Atlanta was adjusted by a factor of 1.64.

^b The operating temperature of the SES TEOM was set to 30°C in Atlanta, but to 35°C in Philadelphia and Baltimore.

^a N/A, not available due to insufficient data.

Additional information

Notes on contributors

Alexander V. Polissar

*Presently at New Jersey Department of Environment Protection, Trenton, New Jersey.

Doh-Won Lee

**Presently at Oak Ridge National Laboratory, Oak Ridge, Tennessee.