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September 2006

8-Stage Non-Viable Impactor Data Reduction Spreadsheet and Supporting Information

Prepared for BGI, Waltham, MA

Patrick T. O'Shaughnessy, PhD

Associate Professor

Department of Occupational and Environmental Health

The University of Iowa

Link to O'Shaughnessy Website

INSTRUCTIONS

This spreadsheet was designed to calculate the mass median aerodynamic diameter (MMAD)

and geometric standard deviation (GSD) associated with a heterogenous aerosol under the

assumption that it exhibits a unimodal log-normal distribution. The method used to determine these

two parameters is based on plotting the cumulative fractions of dust on each stage relative to the

stage cut-diameters on log-probability paper as explained, for example, in the second edition of the

William C. Hinds book, "Aerosol Technology: Properties, Behavior, and Measurement of Airborne

Particles", pages 94-97. A detailed explanation of the spreadsheet development, including an

explanation of the relationship between the slope and intercept of the resulting regression line and theMMAD and GSD, is given in O'Shaughnessy and Raabe, "A Comparison of Cascade Impactor

Data Reduction Methods", Aerosol Science and Technology 37:187-200 (2003).

The calculation sheet contains a column to include "stage effectiveness" values as recommended by

the manufacturer. These values come from a study by Rubow et al. "A Personal Cascade Impactor:

Design, Evaluaition, and Calibration", Am. Ind. Hyg. Assoc. J. 48(6):532-538 (1987).

There are three worksheets:

(1) a worksheet to enter raw data and calculate the MMAD and GSD

(2) a worksheet that develops a graph showing the related histogram of mass-fraction per

stage relative to the ideal lognormal distribution curve, and

(3) a worksheet that calculates the fraction of respirable, thoracic, and inhalable dustas well as PM1, PM 2.5, and PM10

(1) "Log-Prob" calculation worksheet

Enter raw data in cells with blue font.

All calculations needed to determine the MMAD and GSD will be automatically computed.

The "print area" has been selected to print all values and the graph on a single page.

Note: the probability scale shown is not generic to Excel and was developed from information

obtained from a website on Excel "tricks": Link to Simulated Probability Chart Example

This development of a probability scale relies on the use of an Add-In for labels mentioned

in the website. Any adjustments of the plot provided may require that Add-In.

For users familiar with an inverted version of the log-probability plot, one has been

provided at the bottom of the worksheet.

(2) "Histogram" worksheet

This worksheet will be automatically updated when the raw data is entered.

It provides a histogram of the mass-fraction per stage normalized to stage width relative

to the ideal log-normal distribution developed from the resulting MMAD and GSD.

(3) "Fractions" worksheet

This worksheet will be automatically updated when the raw data is entered.

Additional information is given on that sheet.

http://www.public-health.uiowa.edu/academics/faculty/patrick_oshaughnessy.htmlhttp://peltiertech.com/Excel/Charts/ProbabilityChart.htmlhttp://peltiertech.com/Excel/Charts/ProbabilityChart.htmlhttp://www.public-health.uiowa.edu/academics/faculty/patrick_oshaughnessy.html

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8-STAGE NON-VIABLE IMPACTOR DATA REDUCTION

Trial Name: Trial 2 Test Date: 08/01/06

Flow Rate: 28.32 lpm

Calibrated: 08/01/06 Sample Time: 180 min

Cut Diam. Initial Final Net Mass/Stage Cum. Cum.

STAGE NO. mm Weight, mg Weight, mg Weight, mg % % > %