Real-time Measurement of the Size and Composition of Atmospheric Particulate Matter

EPA Grant Number: R826234
Title: Real-time Measurement of the Size and Composition of Atmospheric Particulate Matter
Investigators: Wexler, Anthony S.
Current Investigators: Wexler, Anthony S. , Johnston, Murray V.
Institution: University of Delaware
EPA Project Officer: Shapiro, Paul
Project Period: December 15, 1997 through December 14, 2000
Project Amount: $374,833
RFA: Ambient Air Quality (1997) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Air


Over the last five years we have developed and are using a new class of mass spectrometer. These instruments are capable of distinguishing many atmospheric aerosol constituents such as organic carbon, elemental carbon, and inorganic and crustal compounds. Chemical analysis is a) particle-by-particle so the degree of mixing is elucidated, b) rapid, so volatile compounds are retained, and c) rigorous, in that data is obtained on time scales of seconds. We propose to build a field-portable instrument that sizes and analyzes single particles in the 10 nm to 2 micron size range in year one of the project. In year two, we will test the instrument in Boston in conjunction with Harvard University researchers who, on a separately funded EPA project, are scheduled to measure size and bulk composition of ambient aerosols. In year three, we will analyze the data collected by our new instrument and compare the Harvard size distributions and bulk compositions to our single particle ones.


urrently, we are able to analyze particles over a wide size range, but sizing each particle before analysis is more problematic since light scattering techniques are not effective at the lower end of our size range. We will design and build a new nozzle that can be tuned to aerodynamically transmit a narrow range of particle sizes to the instrument for analysis. The design will be based on aerodynamic particle focussing pioneered by Barton Dahneke. The instrument will cycle the nozzle through the size range of interest, analyzing the transmitted particles. This is similar in concept to a scanning DMA but the size range is much broader for the nozzle and transmission efficiencies have the promise to be much higher.

Expected Results:

Sizing and analyzing atmospheric aerosol particles is limited by the available instrumentation. It is not possible to correlate morbidity and mortality with particulate quantities that are not measured. The instrument we propose will enable measurement of size and composition of individual aerosol particles in real time providing a wealth of data for assessing which component or components of particulate matter are responsible for the observed morbidity and mortality. The current work will develop and assess the capabilities of the instrument. In future work, a number of these instruments could be built and operated for extended periods of time to provide essential data to correlate to health indicators.

Publications and Presentations:

Publications have been submitted on this project: View all 10 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 5 journal articles for this project

Supplemental Keywords:

environmental chemistry, PM10, PM2.5, analytical, measurement methods, RFA, Scientific Discipline, Air, particulate matter, Environmental Chemistry, Environmental Monitoring, Atmospheric Sciences, particle size, particulates, PM10, mass spectrometer, fine particles, PM 2.5, field-portable instruments, Volatile Organic Compounds (VOCs)

Progress and Final Reports:

  • 1998
  • 1999 Progress Report
  • Final Report