Grantee Research Project Results
Final Report: Size-Selection Aerosol Characterization Instrument
EPA Contract Number: EPD12007Title: Size-Selection Aerosol Characterization Instrument
Investigators: Timko, Michael
Small Business: Aerodyne Research Inc.
EPA Contact: Richards, April
Phase: I
Project Period: March 1, 2012 through August 31, 2012
Project Amount: $79,991
RFA: Small Business Innovation Research (SBIR) - Phase I (2012) RFA Text | Recipients Lists
Research Category: SBIR - Air and Climate
Description:
In this SBIR project, Aerodyne Research Inc. (ARI) has developed technologies to improve its existing Aerosol Chemical Speciation Monitor (ACSM) so that it can provide size-resolved aerosol particle composition data for particles. Ambient aerosol particles play a significant role in adversely affecting human health, in altering the chemistry and the radiative balance of the Earth's atmosphere, and in reducing visibility. Recent studies have linked urban particulate pollution to high mortality and morbidity levels, respiratory-related health problems, and increased risk of heart failures in susceptible individuals. The effects of aerosols represent the single largest source of uncertainty in our understanding of global radiative forcing. Because these effects cover many time and length scales, understanding the health and climate effects of ambient particles requires time-resolved measurements of concentrations and compositions over long time periods and in many locations. Moreover, the persistence and distributions of aerosol particles and their potential for health, environmental and climate impacts depend on both particle size and composition. Making size-resolved aerosol composition measurements with the required time resolution and over the length and time scales needed for local and global effects modeling has been impossible due to the lack of automated particle composition monitors. ARI's existing product, the ACSM, provides real-time measurements of particle composition. Moreover, the ACSM is compact, cost effective and can be operated remotely. However, the ACSM lacks size resolution capabilities, and due to its detection scheme, provides limited information on particles > 1 µm.
Summary/Accomplishments (Outputs/Outcomes):
Simulation and experimental activities confirmed that particle dispersion is controlled by imperfections in the aerodynamic lens used as an inlet to ARI's mass spectrometer chamber. Moreover, ARI performed simulations to understand more completely the aerodynamic lens so that it can focus the entire particle size range of interest to the EPA (< 10 µm). Specifically, ARI identified individual components within the lens that will allow ARI to expand the dynamic range and shift the lens transmission to larger particles. Experimental work with multiple lenses verified that ARI can achieve particle dispersion using its aerodynamic lens, though controlling it will be difficult. Multiplexed chopping showed promise as a robust new method for obtaining particle size distribution data, with greater than a 10-fold improvement in signal/noise relative to ARI's current methods.
Conclusions:
ARI has shown that: 1) its improved understanding of aerosol particle focusing can result in a sampling method appropriate for a wide range of particles (< 5 µm has been proven in the laboratory); 2) multiplexed chopping can be used to improve signal-to-noise by a factor of about 10 relative to ARI's current methods; and 3) light scattering methods can be implemented for particles larger than 1 µm. These three advances will enable a next-generation ACSM that packages all of the existing instrument strengths (e.g., cost, size, usability) with size resolution capabilities and improved sensitivity.
Supplemental Keywords:
air pollution, particle monitoring, aerosol particles, aerodynamic lens, light scatter, particle dispersion lens, mass spectrometerSBIR Phase II:
Size-Selecting Aerosol Characterization InstrumentThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.