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Use of passive samplers to estimate PM_10-2.5 by light microscopy

Distributable Zip File With Automated Analysis Routines and Spreadsheets - 4 MB

I recommend using one sample as a recurring quality control standard. There are many issues that can affect image quality and in turn PM estimates.
I'm happy to assist in start up or come to us for analysis of your samples. email

Publications from this work.

Light Microscopy Method. Ott, D.K., W. Cyrs, and T. M. Peters. 2008. Passive measurement of coarse particulate matter, PM10-2.5. J. Aerosol Sci. 39 (2):156-167. http://dx.doi.org/10.1016/j.jaerosci.2007.11.002

Shelter Design. Ott, D.K., and T. M. Peters. 2008. A shelter to protect a passive sampler for coarse particulate matter, PM10-2.5. Aerosol Sci. Technol. 42(4): 299-309. http://dx.doi.org/10.1080/02786820802054236 - Shelter Construction

Field Use. Ott, D.K., N.K. Kumar, and T. M. Peters. 2008. Passive sampling to capture spatial variability in PM10-2.5. Atmospheric Environment 42 (4):746-756. http://dx.doi.org/10.1016/j.atmosenv.2007.09.058

Chemical Speciation of Particles

Analysis by computer-controlled scanning electron microscopy enables measurement of PM_10-2.5 composition.

This work is very exciting to me. We are working on making a chemical map in Cleveland using these techniques.
We have a rich data set from Delhi, India that we will be publishing over the next year. This work is made possible by Dr. Naresh Kumar's grant. Dr. Kumar is a Professor of Geography at the University of Iowa.

Measurements made by Gary Cassucio of RJ Lee Group.

Some history of Iowa's involvement in sampling

The Wagner-Leith passive sampler operates by collecting particles by gravity settling, diffusion, and turbulent inertia. Microscopy is used to determine particle size and surface loading. These data may be used to estimate particulate matter (PM) concentration.

This method was limited in some ways because knowledge of wind speed is needed to estimate the effects of turbulent intertial deposition.

In his PhD dissertation, Darrin Ott developed a shelter for this sampler that reduces the effects of turbulent inertial deposition and makes the sampler easier to deploy in an ambient setting. He did testing in a wind tunnel as shown below.

His results showed that a relatively simple design based on two flat plates drastically reduces wind-dependent deposition as shown below.

The flat-plates shelter also keeps the passive sampler from getting wet.

Estimates of PM_10-2.5 agree well with dichotomous sampler results.

We've used these samplers to assess coarse particle variability in metro areas.

Photos from the field.

Sampling in Los Angeles	Sampling in Iowa

Funding: Pilot grant from CHEEC and US EPA.