Comparison of Ten Source Measurement Techniques for Black Carbon

T.L.B YELVERTON (1), W.P. Linak (1), G.S.W. Hagler (1), M.D. Hays (1), R. Subramanian (2), B.K. Gullett (1)

(1) United States Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Air Pollution Prevention and Control Division, Research Triangle Park, NC. (2) Droplet Measurement Technologies, Boulder, CO

     Abstract Number: 189
     Last modified: April 28, 2010

Abstract
Substantial research and regulatory efforts have focused on ambient air concentrations of particulate matter (PM) due to epidemiological evidence which links ambient exposures with adverse health effects. More recently, black carbon (BC), a component of ambient PM, has also been shown to be an important contributor to changes in global climate. However, unlike carbon dioxide, BC exhibits a relatively short atmospheric residence time, suggesting that controlling BC emissions may have immediate effects on near-term changes in global climate.

Currently, BC is operationally defined through instrumental measurements. Numerous methods and instruments have been and continue to be developed and deployed in the field. The present intercomparison study examines a wide set of semi-continuous and time-integrated measurement techniques and methods widely used to determine particle BC concentrations in the atmosphere and in source combustion emissions. The instruments included in the study are: a multi-angle absorption photometer (MAAP), a transmissometer, aethalometers (rack-mount, portable, and micro), thermal-optical transmittance and reflectance (using IMPROVE, NIOSH 5040, and NIST-EPA methods), a single particle soot photometer (SP2), and a three wavelength photoacoustic soot spectrometer (PASS-3).

The aerosol particle samples being examined include emissions from a heavily diluted laboratory ethylene-air diffusion flame (~30 micrograms/cubic meter) and mobile sources. For the mobile emissions, an on-road EPA electric vehicle capable of rapid-response sampling (real-time or one second sampling) is used. Instrumental data will be compared to manufacturers’ claims of instrument capability as well as statistically compared to one another to interpret the interrelationships between measurements with different methods for BC. Ultimately, this intercomparison study seeks to better understand the abilities of the instruments commonly used for BC concentration measurements under varying combustion conditions and thus gain a better insight to existing emission inventories/databases.