SEARCH METHODOLOGY FOR CONSTRUCTION OF
PIE AND BAR CHARTS USING PM
2.5
SPECIATION DATA
In order to account for uncertainties in the measurement methods of Particulate
Matter of less than 2.5
 g/m 3 (PM
2.5
) and its constituents, SEARCH uses two approaches to represent the measured data. They are FRM Equivalent and
Best Estimate . FRM Equivalent is an attempt to replicate what is being measured by FRM. Best Estimate is an attempt to represent what is actually in the atmosphere. Best Estimate is a consensus representation method arrived at by SEARCH investigators based on monitoring experiences and recent developments in the atmospheric aerosol science. Significant policy ramifications could result based on what method is used to report PM
2.5 mass and its constituent (speciation) data.
Following discussion will focus on what "ingredients" are used to create pie and bar charts using FRM Equivalent and Best Estimate methods.
INGREDIENTS FOR FRM EQUIVALENT PIE/BAR CHART
Mass
Non-blank corrected mass from FRM monitor is used, and the effect of blank is shown in the pie and bar charts. If data from FRM monitor are not available, mass from TEOM monitor measured at 30

Celsius (30C TEOM) or non-blank corrected mass from Channel 1 of Particulate Composition Monitor (PCM1), or mass from TEOM monitor measured at 50

Celsius (50C TEOM) is substituted in that order of availability. Since mass values from different monitors may be averaged for pie and bar chart purposes, a constant blank value of 0.3 ug/m 3 is used.
Nitrate
Non-volatile NO
3
is used from PCM1 Teflon filter or from FRM monitor.
Sulfate
Values from PCM1 monitor are used. If unavailable, values from PCM2 or FRM or Continuous monitors are used in that order of availability.
Ammonium
Values from Channel 2 of PCM (PCM2) or substituted value from PCM1 Teflon or FRM monitor is used.
Elemental Carbon
Values from Channel 3 of PCM (PCM3). No substitutions are made for missing values.
Organic Carbon
Values from PCM3 are used. No substitutions are made for missing values.
Version Date: 01/31/03

For consistency with IMPROVE and EPA, multiplier of 1.4 is used to convert
Organic Carbon to Organic Matter. It is widely recognized that this multiplier is in reality not a constant.
Major Metal Oxides (formerly Crustals)
Aluminum, Calcium, Iron, Potassium, Silica, and Titanium in the highest oxidation state are aggregated to calculate major metal oxides.
INGREDIENTS OF BEST ESTIMATE PIE/BAR CHART
Mass
Blank-corrected mass from FRM monitor or 30C TEOM or PCM1 or 50C TEOM in that order of availability is used as a starting point. To this PCM1 NO3 from
Nylon filter, Equivalent mass of volatile NH4 (0.2903*PCM1 NO
3
Nylon filter), and
Organic Matter from PCM3 backup quartz filter are added. Since PCM3 backup quartz filters are analyzed on a less frequent basis, network-wide quarterly averaged relative ratios of PCM3 quartz filter OC to PCM3 OC are used to derive
PCM3 backup filter OC values. The network-wide quarterly averaged relative ratios of PCM3 quartz filter OC to PCM3 OC [PCM3 backup quartz filter ratio] calculated using 2000-2001 data are 0.062 for quarter 1 (January-March), 0.129 for quarter 2 (April-June), 0.13 for quarter 3 (July-September) and 0.07 for quarter 4 (October-December). As an example, for quarter 2 of any site, PCM3 back up quartz filter OM = 0.129*PCM3 OC *1.4.
Nitrate
Total NO
3
(PCM1 Teflon + PCM1 Nylon) is used. Values from PCM2 or
Continuous monitors are substituted for missing values in that order of availability.
Sulfate
Values from PCM1 monitor are used. If unavailable, values from PCM2 or FRM or Continuous monitors are used in that order of availability. (Same as FRM
Equivalent )
Ammonium
Total NH4 (PCM1 Teflon + equivalent mass of volatile NH4, or PCM2 + equivalent mass of volatile NH4) is used.
Elemental Carbon
Values from Channel 3 of PCM (PCM3). No substitutions are made for missing values. (Same as FRM Equivalent )
Organic Carbon
Values from PCM3 are scaled using the PCM3 backup quartz filter ratio. No substitutions are made for missing values. A multiplier of 1.4 is used to convert
Version Date: 01/31/03

Organic Carbon to Organic Matter. As an example, for quarter 2 of any site,
PCM3 OM = (PCM3 OC+0.129*PCM3 OC)*1.4
Major Metal Oxides (formerly Crustals)
Aluminum, Calcium, Iron, Potassium, Silica, and Titanium in the highest oxidation state are aggregated to calculate major metal oxides. (Same as FRM
Equivalent )
DATA TREATMENT
1) After respective substitution(s) of the individual ingredient(s), a sample is
deleted if one or more component is missing.
2) There has to be a minimum of 5 samples days (rows) in a month to
calculate monthly averages. Monthly averages are used to calculate quarterly
averages. Any quarter with less than 3 month(s) is indicated in the chart.
Quarterly averages are used to calculate annual averages. Any annual
average with less than 4 quarters is indicated.
3) "negative" other is included in average calculations.
4) The above pie charts and bar charts are in general created for both calendar
year and "project year" (Oct'1998 through Sep'1999...etc.,) for each
monitoring site.
SAMPLE PIE CHART USING FRM EQUIVALENT AND BEST ESTIMATE
FRM Equivalent PM
2.5
Composition (
 g/m 3 )
Jefferson St., GA 1999
Average FRM Equivalent mass = 19.1
 g/m
3
, n=286
0.4
1.9
0.5
5.6
6.7
1.9
0.1
2.0
Best Estimate PM
2.5
Composition (
 g/m 3 )
Jefferson St., GA 1999
Average Best Estimate mass = 21.0
 g/m
3
, n=283
0.5
1.8
5.6
7.6
2.0
Version Date: 01/31/03
2.3
1.1