SC IEN

CE

United States

Environmental Protection

Agency

EPA/600/R-08/013 | December 2008 | www.epa.gov/ord

Development of Performance

Data for Common Building Air

Cleaning Devices

FINAL REPORT

Office of Research and Development

National Homeland Security Research Center
ii
EPA/600/R-08/013 | December 2008 | www.epa.gov/ord

iii

FINAL REPORT ON

Development of Performance Data for 

Common Building Air Cleaning Devices

Contract No. GS-10F-0275K

Task Order 1105

Prepared for

Joseph Wood and Les Sparks, Project Officers

U.S. ENVIRONMENTAL PROTECTION AGENCY

Office of Research and Development/National Homeland Security Research Center

Research Triangle Park, NC

Prepared by

Richard Hecker (614) 424-7955

Kent C. Hofacre (614) 424-5639

“WARNING – This document may contain technical data whose export is restricted 

by U.S. law. Violators of export control laws may be subject to severe legal penalties. 

Do not disseminate this document outside the United States or disclose its contents to 

non-U.S. persons except in accordance with applicable laws and regulations and after 

obtaining any required authorizations.”

BATTELLE COLUMBUS OPERATIONS

505 King Avenue

Columbus, Ohio 43201
iv

Disclaimer

The U.S. Environmental Protection Agency through its Office of Research and Development funded 

this research. It has been subject to an administrative review but does not necessarily reflect the views 

of the Agency. No official endorsement should be inferred. EPA does not endorse the purchase or sale 

of any commercial products or services.
v

Table of Contents

List of Acronyms..................................................................................................................................................xi

Executive Summary...........................................................................................................................................xii

1.0 Introduction ....................................................................................................................................................1

2.0 Air Cleaner Device Selection..................................................................................................................3

2.1 Filter Selection................................................................................................................................................3

2.2 Electronic Air Cleaner Selection ....................................................................................................................7

3.0 Experimental Methods................................................................................................................................9

3.1 Inert Aerosol Tests..........................................................................................................................................9

3.1.1 Inert Aerosol Test Method ....................................................................................................................9

3.1.2 Inert Aerosol Data Analysis................................................................................................................10

3.2 Bioaerosol Tests............................................................................................................................................10

3.2.1 Bioaerosol Test Method......................................................................................................................11

3.2.2 Bioaerosol Data Analysis ...................................................................................................................12

3.3 Aging of Air Cleaners for In-Use Tests ........................................................................................................13

3.3.1 Aging of Filters...................................................................................................................................13

3.3.2 Aging of Electronic Air Cleaners .......................................................................................................14

3.4 Conditioning of Electrostatic Filters.............................................................................................................14

3.5 Conditioning of Electronic Air Cleaners Using Silicon Vapor.....................................................................15

4.0 Test Results .....................................................................................................................................................17

4.1Unaged — “Off-the-Shelf ” — Inert Aerosol Evaluations ...........................................................................17

4.1.1 Unaged Filters ....................................................................................................................................17

4.1.2 Unaged Electronic Air Cleaners.........................................................................................................30

4.2 Bioaerosol Penetration..................................................................................................................................32

4.3 Results from the Aging Evaluations.............................................................................................................39

4.3.1 Aging Evaluations – Filters................................................................................................................39

4.3.2 Aging Evaluations – Electronic Air Cleaners.....................................................................................50

4.4 Results from the Conditioning Evaluations..................................................................................................55

4.4.1Results from the Conditioning Evaluations – Filters .........................................................................55

4.4.2 Results from the Conditioning Evaluations – Electronic Air Cleaners..............................................64

4.5 Quality Assurance.........................................................................................................................................67

5.0 Curve Fitting to the “off-the-shelf ”Air Cleaner Results.....................................................69

5.1 Curve Fits to the Inert Aerosol Filter Evaluations........................................................................................69

5.2Curve Fits to the Inert Aerosol Electronic Air Cleaner Evaluations ............................................................75

6.0 Conclusions and Recommendations..................................................................................................77

6.1Results from Inert Aerosol Evaluations of “Off-the-Shelf ” Filters..............................................................77

6.2 Results from Inert Aerosol Evaluations of “Off-the-Shelf ” Electronic Air Cleaners...................................78

6.3Results from Bioaerosol Evaluations of “Off-the-Shelf ” Filters and Electronic Air Cleaners....................78

6.4Results from Aging Evaluations of “Off-the-Shelf ” Filters.........................................................................78

6.5Results from Aging Evaluations of “Off-the-Shelf ” Electronic Air Cleaners..............................................79

6.6Results from Conditioning Evaluations of “Off-the-Shelf ” Filters..............................................................79

6.7Results from Conditioning Evaluations of “Off-the-Shelf ” Electronic Air Cleaners ..................................80

6.8 Recommendations.........................................................................................................................................80

7.0 References .......................................................................................................................................................83

Appendix A: Sample Calculations From the Inert Aerosol Tests...........................................A-1
vi

Appendix B: Sample Calculations From the Bioaerosol Tests................................................B-1

Appendix C: Additional Information on Aging of Filters During The In-Use Tests.......C-1

Appendix D: Photographs of the Various Test Systems Utilized During Inert

Aerosol Testing, Bioaerosol Testing, Aging of Electronic Air Cleaners, 

and Exposure of Electronic Air Cleaners...............................................................D-1

Appendix E: Results From the Inert Aerosol Evaluations of “off-the-shelf ” 

Air Cleaners...............................................................................................................................E-1

Appendix F: Results from the Bioaerosol Evaluations of “off-the-shelf ”

Air Cleaners............................................................................................................................... F-1

Appendix G: Results From the Inert Aerosol Evaluations of the

Aged Air Cleaners ..................................................................................................................G-1

Appendix H: Results From the Inert Aerosol Evaluations of the Conditioned

Air Cleaners ..............................................................................................................................H-1

Appendix I: Quality Assurance...................................................................................................................I-1
vii

List of Tables

Table 2-1. Test Matrix for Filter Evaluation...............................................................................................................3

Table 2-2. Approximate Shares of the U.S. Air Filter Market (McIlvaine, 2002) .....................................................4

Table 2-3. Evaluated Residential Filters.....................................................................................................................5

Table 2-4. Evaluated Commercial Filters...................................................................................................................6

Table 2-5. Recommended Test Matrix for Electronic Air Cleaner Evaluations from the Statement of Work ...........7

Table 2-6. Evaluated Electronic Air Cleaners ............................................................................................................7

Table 4-1. Results from the Inert Aerosol Evaluations of “Off-the-Shelf ” Residential Filters................................18

Table 4-2. Results from the Inert Aerosol Evaluations of “Off-the-Shelf ” Commercial Filters..............................19

Table 4-3. Results from the Inert Aerosol Evaluations of “Off-the-Shelf ” Electronic Air Cleaners.......................31

Table 4-4. Summary of the Results from the Bioaerosol Evaluations......................................................................33

Table 4-5. Summary of the Results from the Filter Aging Evaluations ...................................................................40

Table 4-6. Summary of the Results from the Electronic Air Cleaner Aging Evaluations........................................51

Table 4-7. Summary of the Results from the Filter Conditioning Evaluations........................................................56

Table 4-8. Summary of the Results from the Silicon Vapor Exposures of the Electronic Air Cleaners ..................65

Table 5-1. Summary of the Results from the Curve Fits to the Inert Aerosol Evaluations of Unaged

Unconditioned Air Filters........................................................................................................................70

Table 5-2. Summary of the Results from the Curve Fits to the Inert Aerosol Evaluations of Unaged

Unconditioned Electronic Air Cleaners...................................................................................................75

Table 6-1. Summary of the Results from the Inert Aerosol Evaluations and Curve Fits of Unaged

Unconditioned Air Filters........................................................................................................................78

List of Figures

Figure 2-1. EAC Air Filtration Mechanism .................................................................................................................7

Figure 3-1. Aerosol Sampling Instruments, TSI SMPS (left) and Climet CI-500 (right)............................................9

Figure 3-2. Schematic of the Bioaerosol Test Rig .....................................................................................................11

Figure 4-1. Measured Collection Efficiencies of Unaged MERV 5 Filters ...............................................................21

Figure 4-2. Measured Pressure Drops of Unaged MERV 5 Filters............................................................................21

Figure 4-3. Measured Collection Efficiencies of Unaged MERV 6 Filters ...............................................................22

Figure 4-4. Measured Pressure Drops of Unaged MERV 6 Filters............................................................................22

Figure 4-5. Measured Collection Efficiencies of Unaged MERV 7 Filters ...............................................................23

Figure 4-6. Measured Pressure Drops of Unaged MERV 7 Filters............................................................................23

Figure 4-7. Measured Collection Efficiencies of Unaged MERV 8 Filters ...............................................................24

Figure 4-8. Measured Pressure Drops of Unaged MERV 8 Filters............................................................................24

Figure 4-9. Measured Collection Efficiencies of Unaged MERV 10 Filters .............................................................25

Figure 4-10. Measured Pressure Drops of Unaged MERV 10 Filters..........................................................................25

Figure 4-11. Measured Collection Efficiencies of Unaged MERV 12 Filters .............................................................26

Figure 4-12. Measured Pressure Drops of Unaged MERV 12 Filters..........................................................................26

Figure 4-13. Measured Collection Efficiencies of Unaged MERV 14 Filters .............................................................27

Figure 4-14. Measured Pressure Drops of Unaged MERV 14 Filters .........................................................................27

Figure 4-15. Measured Collection Efficiencies of Unaged MERV 16 Filters .............................................................28

Figure 4-16. Measured Pressure Drops of Unaged MERV 16 Filters..........................................................................28

Figure 4-17. Measured Collection Efficiency of Unaged MERV 16+ (HEPA) Filter .................................................29

Figure 4-18. Measured Pressure Drop of Unaged MERV 16+ (HEPA) Filter.............................................................29

Figure 4-19. Measured Collection Efficiency of Unaged Electronic Air Cleaners......................................................30

Figure 4-20. Measured Pressure Drops of Unaged Electronic Air Cleaners................................................................32

Figure 4-21. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency

Measurements for Filter 2NS-8-1............................................................................................................34

Figure 4-22. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency

Measurements for Filter 4FUA-12-1.......................................................................................................34

Figure 4-23. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency

Measurements for Filter 8NM-10-1 ........................................................................................................35
viii

List of Figures

Figure 4-24. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency 

Measurements for Filter 6DDUE-8-12....................................................................................................35

Figure 4-25. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency

Measurements for Electronic Air Cleaner A............................................................................................36

Figure 4-26. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency

Measurements for Electronic Air Cleaner H...........................................................................................36

Figure 4-27. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency

Measurements for Electronic Air Cleaner P............................................................................................37

Figure 4-28. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency

Measurements for Filter C15AAA-11-BIO.............................................................................................37

Figure 4-29. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency

Measurements for Filter C17FPP-8-BIO ................................................................................................38

Figure 4-30. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency

Measurements for Filter C11GM-16-BIO...............................................................................................38

Figure 4-31. Measured Collection Efficiency of Residential Filter 6DDUE-8 During the Aging Evaluations...........43

Figure 4-32. Measured Pressure Drop of Residential Filter 6DDUE-8 During the Aging Evaluations......................43

Figure 4-33. Measured Collection Efficiency of Residential Filter 8NM-10 During the Aging Evaluations .............44

Figure 4-34. Measured Pressure Drop of Residential Filter 8NM-10 During the Aging Evaluations.........................44

Figure 4-35. Measured Collection Efficiency of Commercial Filter C17FPP-8 During the Aging Evaluations.........45

Figure 4-36. Measured Pressure Drop of Commercial Filter C17FPP-8 During the Aging Evaluations....................45

Figure 4-37. Measured Collection Efficiency of Commercial Filter C15AAA-11 During the Aging Evaluations.....46

Figure 4-38. Measured Pressure Drop of Commercial Filter C15AAA-11 During the Aging Evaluations................46

Figure 4-39. Measured Collection Efficiency of Commercial Filter C8GZ-13 During the Aging Evaluations..........47

Figure 4-40. Measured Pressure Drop of Commercial Filter C8GZ-13 During the Aging Evaluations .....................47

Figure 4-41. Measured Collection Efficiency of Commercial Filter C14PCS During the Aging Evaluations............48

Figure 4-42. Measured Pressure Drop of Commercial Filter C14PCS During the Aging Evaluations.......................48

Figure 4-43. Measured Collection Efficiency of Commercial Filter C11GM-16 During the Aging Evaluations.......49

Figure 4-44. Measured Pressure Drop of Commercial Filter C11GM-16 During the Aging Evaluations ..................49

Figure 4-45. Measured Collection Efficiency of Electronic Air Cleaner A During the Aging Evaluations ................52

Figure 4-46. Measured Pressure Drop of Electronic Air Cleaner A During the Aging Evaluations............................52

Figure 4-47. Measured Collection Efficiency of Electronic Air Cleaner H During the Aging Evaluations................53

Figure 4-48. Measured Pressure Drop of Electronic Air Cleaner H During the Aging Evaluations...........................53

Figure 4-49. Measured Collection Efficiency of Electronic Air Cleaner P During the Aging Evaluations.................54

Figure 4-50. Measured Pressure Drop of Electronic Air Cleaner P During the Aging Evaluations............................54

Figure 4-51. Measured Collection Efficiency of Filter 6DDUE-8-11 During the Conditioning Evaluations.............58

Figure 4-52. Measured Collection Efficiency of Residential Filter 6DDUE-8 During the Aging Evaluations...........58

Figure 4-53. Measured Collection Efficiency of Filter 5RM-11-1 During the Conditioning Evaluations..................59

Figure 4-54. Measured Collection Efficiency of Filter 4FUA-12-3 During the Conditioning Evaluations................59

Figure 4-55. Measured Collection Efficiency of Filter 7AST-8-3 During the Conditioning Evaluations...................60

Figure 4-56. Measured Collection Efficiency of Filter 8NM-10-11 During the Conditioning Evaluations................60

Figure 4-57. Measured Collection Efficiency of Residential Filter 8NM-10 During the Aging Evaluations .............61

Figure 4-58. Measured Collection Efficiency of Filter C15AAA-11 During the Conditioning Evaluations ..............61

Figure 4-59. Measured Collection Efficiency of Commercial Filter C15AAA-11 During the Aging Evaluations.....62

Figure 4-60. Measured Collection Efficiency of Filter C17FPP-8 During the Conditioning Evaluations..................62

Figure 4-61. Measured Collection Efficiency of Commercial Filter C17FPP-8 During the Aging Evaluations.........63

Figure 4-62. Measured Collection Efficiency of Filter C8GZ-13 During the Conditioning Evaluations....................63

Figure 4-63. Measured Collection Efficiency of Commercial Filter C8GZ-13 During the Aging Evaluations..........64

Figure 4-64. Measured Collection Efficiencies for Electronic Air Cleaner A Before and After Exposure 

to Silicon Vapor.......................................................................................................................................66

Figure 4-65. Measured Collection Efficiencies for Electronic Air Cleaner H Before and After Exposure

to Silicon Vapor.......................................................................................................................................66

Figure 4-66. Measured Collection Efficiencies for Electronic Air Cleaner P Before and After Exposure

to Silicon Vapor.......................................................................................................................................67
ix

List of Figures

Figure 5-1. Curve Fit to the Empirical Data for the Single Unaged, Unconditioned MERV 5 Filter........................71

Figure 5-2. Curve Fit to the Empirical Data for the Two Unaged, Unconditioned MERV 6 Filters.........................71

Figure 5-3. Curve Fit to the Empirical Data for the Six Unaged, Unconditioned MERV 7 Filters...........................72

Figure 5-4. Curve Fit to the Empirical Data for the Four Unaged, Unconditioned MERV 8 Filters.........................72

Figure 5-5. Curve Fit to the Empirical Data for the Single Unaged, Unconditioned MERV 10 Filter......................73

Figure 5-6. Curve Fit to the Empirical Data for the Five Unaged, Unconditioned MERV 12 Filters.......................73

Figure 5-7. Curve Fit to the Empirical Data for the Four Unaged, Unconditioned MERV 14 Filters.......................74

Figure 5-8. Curve Fit to the Empirical Data for the Three Unaged, Unconditioned MERV 16 Filters.....................74

Figure 5-9. Curve Fit to the Empirical Data for the Single Unaged, Unconditioned MERV 16+ (HEPA) Filter......75

Figure 5-10. Curve Fit to the Empirical Data for the Six Unaged, Unconditioned Electronic Air Cleaners...............76
x

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xi

List of Acronyms

ANSI American National Standards Institute

ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers

BG Bacillus globigii

CB chemical or biological

CDC Centers for Disease Control and Prevention

CFM cubic feet per minute

CFU colony forming unit

COTR Contracting Officer’s Technical Representative

CT time-integrated concentration (concentration*time)

CV coefficient of variation

E1 average efficiency for particles with physical diameters between 0.3 μm and 1 μm

E2 average efficiency for particles with physical diameters between 1 μm and 3 μm

E3 average efficiency for particles with physical diameters between 3 μm and 10 μm

EAC electronic air cleaner

EPA Environmental Protection Agency

ETV Environmental Technology Verification

fpm feet per minute

g grams

HEPA high efficiency particulate air

HVAC heating, ventilation, and air conditioning

in. inches

in. w. g. inches of water gauge

inHg inches of mercury

KCl potassium chloride

MERV Minimum Efficiency Reporting Value

NA not available

OPC optical particle counter

ORD Office of Research and Development

PBS phosphate-buffered saline

PSI pounds per square inch

QA quality assurance

QAPP Test/Quality Assurance Project Plan

SMPS Scanning Mobility Particle Sizer

SOP standard operating procedure

SOW statement of work

TSA tryptic soy agar

μm micrometer
xii

Executive Summary

Recent events have shown that buildings are vulnerable 

to terrorist attacks involving biological agents. The most 

serious effects of such an attack are on the health of the 

occupants of the buildings. Building occupants may suffer 

health effects ranging from irritation to severe sickness to 

death. An attack may also have long-term economic and 

other impacts due to contamination of the building. Several 

organizations, including the Army Corps of Engineers, 

the American Society of Heating, Refrigerating and AirConditioning Engineers (ASHRAE), and the Centers for 

Disease Control and Prevention (CDC), recognize this 

terrorist threat and have issued guidance documents on 

how to deal with it. These documents, while useful, suffer 

from the fact that the scientific, engineering, and economic 

information needed to determine optimum courses of 

action is inadequate. The tools and technologies required 

to implement optimum courses of action are often not 

available, are too expensive to use, or are inadequate.

The work described in this document was performed under a 

broader project to investigate building air cleaning systems’ 

effectiveness in removing biologically active particles from 

air. This report in particular describes the results of an effort 

to collect performance data (pressure drop and collection 

efficiency for biological and non-biological aerosols) on 24 

commonly used ventilation filters and on 3 commercially 

available electronic air cleaners (EACs). For both sets of 

air cleaners, tests were performed with both “off-the-shelf ” 

units and with a selected subset of units aged in a typical or 

simulated use environment to allow a better understanding of 

how the units would likely perform over their entire service 

lives. In addition, testing was performed on a select subset 

of units against a bioaerosol to demonstrate the similarity in 

performance between inert and biological particles. Empirical 

equations were developed that relate particle collection 

efficiency to particle physical diameter over the range of 

0.03 to 10 μm. These equations can be incorporated into 

indoor air quality models.

Results from Inert Aerosol Evaluations of 

“Off-the-Shelf ” Filters

The measured pressure drops of the “off-the-shelf ” filters 

generally corresponded quite well (± 30%) with the 

information provided by the vendors, although, in a few 

cases, the measured pressure drops were somewhat greater. 

With the exception of several Minimum Efficiency Reporting 

Value (MERV) 11 filters, the MERV ratings that were 

determined from the tests were generally equivalent or within 

one or two MERV ratings reported by the manufacturer. 

The testing during this study consisted of evaluating single 

filters; therefore, the results may not be representative of 

typical performance. (Note: The ANSI/ASHRAE 52.2-1999 

standard does not provide any guidance as to the number of 

samples of a filter type that should be tested to ensure that the 

manufacturer-reported MERV rating provides a statistically 

reasonable representation of their performance.)

For the filters tested, which covered all of the MERV ratings, 

collection efficiencies determined from measurements made 

with the Climet model 500 Spectrometer optical particle 

counter (OPC) (0.3 to 10 μm) generally corresponded very 

well with the collection efficiencies determined using the TSI 

Scanning Mobility Particle Sizer (SMPS) (0.03 to 0.3 μm). 

The most penetrating particle size was consistently in the 0.1 

to 0.3 μm range, which is consistent with typical filtration 

efficiency curves. Table ES-1 provides a summary of the 

results from the inert aerosol evaluations of unconditioned, 

unaged (“off-the-shelf ”) filters. As shown in Table ES-1, 

the pressure drops of the filters between MERV 5 and 10 at 

370 feet per minute (fpm) did not appear to be substantially 

different, with a good deal of overlap between the average 

pressure drops. However, there was a significant increase in 

pressure drops between the MERV 10 and MERV 12 filters, 

between the MERV 14 and MERV 16 filters, and between 

the MERV 16 filters and the HEPA (MERV >16) filter. As 

expected, the collection efficiency of the filters generally 

increased with MERV rating. Therefore, consumers of air 

filters will need to balance the higher pressure drops and cost 

of MERV 12 to MERV 16 filters with the expected increase 

in performance.

Table ES-2 lists the results from the curve fitting analysis 

(the development of equations to predict particle penetration 

as a function of particle size, based on the experimental 

data) for the “off-the-shelf ” filters. As shown in Table 

ES-2, all but one of the curve fits possessed correlation 

coefficients (r squared) greater than 0.89, indicating an 

excellent representation of the data. The MERV 6 curve fit 

possessed a lower correlation value of 0.83. In all cases, 

it is not recommended that the equations be extrapolated 

outside of the particle size range used (0.03 to 10 μm). These 

curve fits provide a valuable tool that will enable consumers 

to accurately estimate the collection efficiency of a filter 

with a given MERV rating to determine whether its likely 

performance will justify its increased cost and pressure drop.
xiii

Table ES-1. Summary of the Results from the Inert Aerosol Evaluations and Curve Fits of

Unaged Unconditioned Air Filters

MERV 

Rating

Number of 

Filters Tested

Average 

Pressure Drop 

(in. of water) at 

370 fpm

Predicted Collection Efficiencies from Curve Fits (%)

0.03 μm 0.1 μm 0.3 μm 1.1 μm 3.5 μm 8.4 μm

5 1 0.24 13 0 5 24 34 34

6 2 0.22 + 0.06 12 6 5 16 35 53

7 6 0.30 + 0.08 44 13 20 47 61 65

8 4 0.26 + 0.03 40 20 22 52 75 86

10 1 0.29 55 37 29 53 85 97

12 5 0.46a + 0.09 71 47 49 78 95 99

14 4 0.48b + 0.11 82 59 68 93 99 99

16 3 0.73 + 0.15 99 95 96 99 99 99

16+ (HEPA) 1 0.97 >99 >99 >99 >99 >99 >99

a

 – neglecting electrostatic filter 4FUA-12-3, which had a pressure drop of only 0.13 inches of water

b

 – neglecting filter C6-ADP-15-1, which was evaluated well above its nominal flow rate

Table ES-2. Summary of the Results from the Curve Fits to the Inert Aerosol Evaluations of

Unaged Unconditioned Air Filters

MERV Rating Equation Parameters Correlation Coefficient (r2)

5 Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 1.8906

b = -0.1722

c = 0.0307

d = 0.0793

0.8935

6 Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 1.9311

b = -0.1441

c = -0.1243

d = -0.0234

0.8332

7 Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 1.7467

b = -0.3314

c = -0.0036

d = 0.1381

0.9064

8 Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 0.5839

b = 0.1675

c = 0.1289

d = 0.0188

0.9658

10 Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 1.7083

b = -0.5759

c = -0.6721

d = -0.1775

0.9852

12 Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 1.3943

b = -0.9080

c = -0.6240

d = -0.0404

0.9902

14 Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 0.9531

b = -1.4941

c = -0.8443

d = -0.0013

0.9668

16 Ln Y = a + bx + cx2 + dx3

where Y = percent penetration

x = log of particle diameter

a = 0.3855

b = -2.0698

c = 0.5326

d = 1.3895

0.9728

16+ (HEPA) Y = a + bx + cx2 + dx3 + ex4

where Y = percent penetration

x = log of particle diameter

a = 0.0361

b = -0.3506

c = 0.5119

d = 0.0481

e = -0.1816

0.8917
xiv

Table ES-3. Summary of the Results from the Curve Fits to the Inert Aerosol Evaluations of Unaged

Unconditioned Electronic Air Cleaners

MERV Rating Equation Parameters Correlation Coefficient (r2)

14 and 15 (all unaged 

unconditioned EACs)

Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 0.8422

b = -0.6469

c = -0.2157

d = 0.1645

0.9600

Results from Inert Aerosol Evaluations of “Off-the-Shelf” 

Electronic Air Cleaners

The measured pressure drops of two of the three tested units 

(A and P) corresponded well with the information provided 

by the manufacturers, while the pressure drop for Unit H was 

nearly double the expected value. The measured pressure 

drops for the EACs averaged 0.14 + 0.03 inches of water at 

370 feet per minute (fpm), which is approximately one-half 

that of the average pressure drop for MERV 5 to 10 filters. 

Given that the EACs possessed MERV ratings of 14 and 15, 

at least initially, they appeared to offer considerably higher 

collection efficiency than air filters for a given pressure 

drop. In terms of collection efficiency, the MERV ratings 

that were determined from the tests ranged from one MERV 

rating below to three MERV ratings above the manufacturerreported value. Note that the testing during this study 

consisted of evaluating pairs of units; therefore, the results 

may not be representative of typical performance. 

As with the filters, collection efficiencies determined with 

the OPC (0.3 to 10 μm) generally corresponded very well 

with the collection efficiencies determined using the SMPS 

(0.03 to 0.3 μm). A single curve was fit with an excellent 

correlation (r squared value of 0.96) to all of the “off-theshelf ” EAC results; the results are listed in Table ES-3. 

This empirical model may be used for predicting the likely 

collection efficiency of an electronic air cleaner with a 

MERV rating of 14 or 15.

Results from Bioaerosol Evaluations of “Off-the-Shelf ” 

Filters and Electronic Air Cleaners

A select group of filters (seven) and EACs (three) were 

evaluated against a bioaerosol challenge. The purpose of 

the bioaerosol tests was to compare the penetration of a 

bioaerosol to the penetration of a similarly sized inert aerosol 

to determine whether there were any significant differences 

between the penetration of bioaerosol and inert particles.

Similar to previously reported results (RTI, 2004), in nine of 

the ten tests, the measured bioaerosol collection efficiencies 

generally exceeded the average collection efficiency for 

inert particles with physical particle diameters between 0.3 

and 1 μm but were generally less than or equivalent to the 

inert aerosol collection efficiency results for 1- to 3-μm 

particles. For the remaining filter (6DDUE-8, an EAC), only 

a 6% collection efficiency was measured but with a large 

standard deviation. When the standard deviation is taken 

into consideration, the test results are likely in reasonable 

agreement. Overall, the results indicate that the collection 

efficiency for bioaerosol particles is similar to comparably 

sized inert particles.

Results from Aging Evaluations of “Off-the-Shelf ” Filters

For a select group of filters (seven), simulated aging tests 

were performed with inert aerosols to examine the effect of 

dust loading in actual use environments on the collection 

efficiencies and pressure drops of the units.

For the two electrostatic residential filters (6DDUE-8 and 

8NM-10), the collection efficiency for larger particles (3.0 

to 10.0 μm) either increased significantly (6DDUE-8) or 

remained the same (8NM-10) after the filters started to be 

loaded with particles. However, for both filters, a substantial 

decrease in collection efficiency was noted for smaller 

particles (0.3 to 3 μm) after the filters were loaded. The 

collection efficiency of the filters for smaller particles did not 

exceed the initial efficiency until between 8 and 12 weeks of 

loading had occurred. The pressure drops of both residential 

filters remained fairly consistent through the first 8 weeks of 

use; the pressure drop then increased greatly between weeks 

8 and 12. It should be noted that 12 weeks of use constitutes 

100% of the manufacturer-recommended service time for 

these two filters.

Similarly, the two electrostatic commercial prefilters 

(C17FPP-8 and C15AAA-11) demonstrated consistent 

average collection efficiencies for larger particles (4.0 to 

10.0 μm) over the entire 16-week test. However, there was 

a very substantial drop in collection efficiency for particles 

smaller than approximately 4 μm once the loading began, 

and the collection efficiency for the smaller particles never 

returned to the measured initial values. The pressure drops of 

the two prefilters did not demonstrate any noticeable increase 

over the aging period. The typical service life for prefilters 

in the heating, ventilation, and air conditioning (HVAC) 

system of interest ranges from 3 to 6 months, so the 4 months 

of aging that was performed represented between 67% and 

133% of a typical service period. It should be noted that the 

performance of Filter C15AAA-11 was considerably poorer 

than was expected from the manufacturer’s literature.

In contrast, the 12-inch deep electrostatic commercial 

box filter (C8GZ-13) substantially degraded in collection 

efficiency for all particle sizes over the entire aging period, 

dropping steadily from MERV 12 to MERV 10. No change 

in pressure drop occurred over this period, implying that a 

suitable dust cake did not form during loading, which would 

likely have caused the degradation of collection efficiency 

to slow. The range of service life for filter C8GZ-13 in the 

application of interest is 6 to 12 months, with typical usage 

closer to 12 months, so the aging period represented only 

33% to 67% of the typical service life.

As expected, the two commercial, 12-inch deep, nonelectrostatic, traditional fiberglass media deep-pleated 
xv

filters (C14PCS and C11GM-16) did not demonstrate any 

degradation in collection efficiency during the aging period. 

In fact, the collection efficiency of filter C14PCS clearly 

increased as dust was collected on the filter during aging. No 

change in pressure drop was noted over the aging period for 

these two filters. The typical service life for these two filters 

in the application of interest is 6 to 12 months (typically 

closer to 12 months), so the aging period represented only 

33% to 67% of the typical service life.

Results from Aging Evaluations of “Off-the-Shelf” 

Electronic Air Cleaners

For the EACs (three), aging was performed using an inert 

aerosol to examine the effect of dust loading in actual use 

environments on the collection efficiency and pressure drop 

of the units. Cleaning was not performed over the entire 

aging duration. This was consistent with the manufacturers’ 

recommendations of cleaning intervals between one and 

six months in duration. The manufacturers’ literature 

recommended cleaning only when a visual inspection 

indicated that one was required.

As expected, the pressure drops of all three units remained 

consistent over the entire aging period. Unit A demonstrated 

nearly no degradation in performance over the entire 

2,016 hour aging period, having just a minor decrease in

the average efficiency for 0.3- to 1-μm particles (from 87.6% 

to 80.7%).

Unit H performed reasonably well but showed more 

degradation than Unit A, dropping from a MERV 15 to a 

MERV 12 over the aging period. While the MERV rating 

remained consistent for the first 1,008 hours of aging, after 

2,016 hours of operation, its MERV rating dropped to 12, 

indicating that cleaning after 84 days of continuous operation 

was warranted.

In contrast, Unit P dropped precipitously from a MERV 

14 to a MERV 6 between 336 hours and 1,008 hours of 

use. Despite the significant drop in collection efficiency, 

the visible buildup on the unit was not substantial enough 

to clearly warrant cleaning. Unit P was not visibly dirtier 

than the other two units, so the user would have no reason 

to suspect that performance had substantially degraded. 

However, based on its collection efficiency, cleaning

of Unit P would be recommended after 14 days of

continuous use.

Results from Conditioning Evaluations of 

“Off-the-Shelf ” Filters

Eight filters (all electrostatic) were evaluated using an inert 

aerosol test method that involved conditioning the filter 

with submicron potassium chloride particles to identify the 

loading or conditioning level that resulted in the minimum 

collection efficiency. The test method used was from the draft 

Addendum C to ANSI/ASHRAE Standard 52.2-1999. The 

purpose of the conditioning tests was to compare results with 

the aging tests to determine whether the draft Addendum 

C test method provided a suitable means for accurately 

simulating the performance over time of an electrostatic filter 

in a typical use environment.

Four of the residential electrostatic filters performed similarly 

during the conditioning evaluations. Upon conditioning, 

the collection efficiency increased significantly for particles 

larger than approximately 1 to 2 μm but appeared to decrease 

slightly or remain constant for particles smaller than 1 to 

2 μm. This was consistent with the observed trend during the 

aging tests of one of the residential filters, during which the 

collection efficiency increased upon aging for particles larger 

than 4 μm but decreased significantly for particles smaller 

than 2 μm.

For a fifth residential filter, the collection efficiency 

decreased slightly for all particles upon initial conditioning 

but increased for all particles once the equivalent of one 

month of conditioning had been performed. This trend was 

similar to the results observed during the aging tests for the 

same filter, although the decrease in collection efficiency

was more substantial and required approximately 12 weeks 

of aging for the collection efficiency to increase past the 

initial values.

The aging and conditioning tests of one commercial 

prefilter also appeared to be consistent. Conditioning of the 

commercial prefilter resulted in a noticeable decrease in 

collection efficiency for all particles less than approximately 

1 μm, with no recovery during the approximately one month 

equivalent of conditioning. Aging of the prefilter also resulted 

in a decrease (although more substantial) in collection 

efficiency for all particles smaller than approximately 4 μm, 

with no recovery over 16 weeks of aging.

In contrast, the aging and conditioning tests of the remaining 

two commercial filters did not produce consistent results. For 

a commercial prefilter, the collection efficiency increased 

slightly for all particles upon initial conditioning and 

remained at the same level with further conditioning. This 

result noticeably contrasted with the results from the aging 

evaluations, in which the collection efficiency decreased 

substantially for particles smaller than 4 μm with aging and 

did not increase over 16 weeks of use. For a commercial box 

filter, the results from the aging and conditioning evaluations 

contrasted even more strongly. In the conditioning evaluation, 

the collection efficiency remained essentially constant during 

the approximately one month equivalent of conditioning, 

even increasing slightly for particles smaller than 0.3 μm. 

However, during the entire 16 weeks of aging, the box 

filter consistently and continually decreased in collection 

efficiency for all particles.

It is not known why the trends in the results from the 

conditioning evaluations are consistent with the aging results 

for some but not all of the filters. Further investigation of 

these contrasting results seems warranted but was beyond 

the scope of this effort. It should be noted that during the 

conditioning evaluations, only a single filter of each type 

was tested. In contrast, the aging evaluations were performed 

with five different filters of identical make, model, and size. 

Therefore, some variability is present in the aging evaluations 

due to the different performance levels of the individual 

filters, whereas the analysis of variability for the conditioning 

tests for a particular type of filter is not feasible.
xvi

Results from Conditioning Evaluations of “Off-the-Shelf ” 

Electronic Air Cleaners

Three EACs were evaluated both before and after 

conditioning with silicon vapor. The purpose of the exposure 

to silicon vapor was to determine whether this conditioning 

approach resulted in filter performance similar to the 

performance of the EACs after one month of actual use.

The exposure of Units A and P to silicon vapor appeared 

to cause a very similar level of degradation in performance 

compared to that likely to be observed after one month of 

ambient aging (672 hours of use). For both of these units, 

the collection efficiency of the EAC degraded more than 

that observed during 336 hours (2 weeks) of ambient use 

but less than that observed after 1,008 hours (6 weeks) of 

ambient use.

For Unit H, however, the silicon vapor exposure degraded 

the unit’s performance well beyond that observed after 

even 2,016 hours of ambient aging (12 weeks of continuous 

operation).

It is not known why the results from the aging and 

conditioning evaluations are consistent for units A and P 

but inconsistent for Unit H. It could be a result of design 

and component differences between the three units. Given 

the approximately 50% decrease in pressure drop in Unit H 

after silicon vapor exposure, and the alteration in the shape 

of the collection efficiency curve, it is possible that the 

exposure allowed leakage to occur within the unit. Further 

investigation of the contrasting results for Unit H seems 

warranted but was beyond the scope of this effort.

It should be noted that in contrast to the filter evaluations, 

during the EAC aging evaluations, a single unit was 

used. Therefore, no variability data are available for the

EAC aging evaluations. 

Recommendations

As a result of this effort, empirical models (curve fits) 

are now available that provide a valuable tool enabling 

researchers and consumers to accurately estimate the 

collection efficiency (by particle size) of a filter or EAC 

with a given MERV rating and determine whether its likely 

performance will justify its increased cost and pressure drop. 

Unfortunately, due to a combination of a limited test matrix 

and some filters that did not perform as anticipated, data for 

filters performing at MERV ratings of 9, 11, 13, and 15 were 

not acquired. Therefore, future efforts should be performed to 

capture data for these MERV ratings. In addition, acquiring 

additional data for filters with MERV ratings of 5 and 10 is 

desirable, as only one filter was available at that performance 

rating in the current study.

Also, it was observed during this study that a number of 

filters did not perform in accordance with the MERV ratings 

provided by the filter vendors. Although in many cases, the 

performance was only a few percentage points below the 

vendor-provided rating, in some cases, the performance was 

three or four MERV ratings below. Because the standard for 

establishing MERV ratings (ANSI/ASHRAE 52.2-1999) 

does not currently provide any guidance as to the number of 

samples of a filter type that should be tested to ensure that the 

manufacturer-reported MERV rating provides a statistically 

reasonable representation of their performance, currently, 

an evaluation of a single filter could be used to characterize 

the performance of a very large number of filters. A study 

investigating the consistency of performance for filters at a 

given MERV rating is recommended to enable consumers to 

make better-informed decisions about the likely performance 

of purchased filters.

In this study, EACs appeared to be an excellent choice for 

residential air cleaning, as they provided substantially higher 

collection efficiencies than are available from residential 

filters at a fraction of the pressure drop. Evaluations of their 

performance to better define the likely frequency of cleaning 

and the collection efficiency performance as a function of the 

number of cleaning cycles are needed to compare the longterm operational costs of EACs to those of air filters.

The results from this study indicated that the conditioning 

procedures for electrostatic filters described in Addendum 

C of ANSI/ASHRAE 52.2-1999 warrant additional 

investigation. Although the results from aging and 

conditioning via Addendum C demonstrated similar trends 

for residential electrostatic filters, the results from the 

commercial filters contrasted strongly.

Similarly, the silicon vapor exposure conditioning method 

that was investigated for EACs would benefit from additional 

study. For two of the three units evaluated, the results 

between the aging and conditioning methodology showed 

very good agreement; however, for the third unit, the results 

contrasted significantly. While these results seem promising 

for the silicon vapor exposure method, additional study and 

refinement may be warranted.

For the inert particles, size measurements were made using 

a light-scattering technique (0.3 to 10 μm) and a technique 

based on electrical mobility (0.03 to 0.3 μm). In general, 

the collection efficiency measured at the lowest size bin 

for the larger range (0.35 μm midpoint) was within 10% 

of the highest size bin of the smaller size range (0.294 μm 

midpoint). Often, the agreement was much closer. However, 

to our knowledge a study to assess the agreement between 

the two measurement methods in a range of overlapping 

particle sizes has not been performed. It is recommended that 

research be performed to investigate the differences between 

these different measurement techniques in the overlapping 

size range.
1

1.0

Introduction

Concerns persist that buildings are vulnerable to terrorist 

attack using biological agents. The most serious effects 

of such an attack are on the health of the occupants of the 

buildings. Building occupants may suffer health effects 

ranging from irritation to severe sickness to death. The 

attack may also have long-term economic and other 

impacts due to contamination of the building. Several 

organizations, for example, the Army Corps of Engineers, 

ASHRAE, and CDC, have recognized this terrorist threat 

and have issued guidance documents on how to deal with 

it. These documents, while useful, lack the scientific, 

engineering, and economic information needed to determine 

optimum courses of action. Tools and technologies to 

implement optimum courses of action are often not 

available, are too expensive to use, or are inadequate.

The work described in this document was conducted to 

develop performance information (pressure drop and 

collection efficiency for biological and non-biological 

aerosols) on a wide range of commonly used ventilation 

filters and on three commercially available EACs that 

could be used in HVAC systems. For both types of aerosol 

reduction technologies, tests were performed with both 

“off-the-shelf ” units and with units aged in a typical or 

simulated use environment to allow a better understanding of 

how the units would likely perform over their entire service 

life. In addition, testing was performed on a select subset 

of units using a bioaerosol to demonstrate the similarity in 

performance with inert particles. Empirical equations were 

then developed that relate particle collection efficiency to 

particle physical diameter over the range of 0.03 to 10 μm. 

These equations can be incorporated into indoor air quality 

models. (It should be noted that the publicly available 

performance data for filters and EACs have been typically 

reported for particles between 0.3 and 10 μm. However, 

within the past three to four years it has become feasible 

to economically measure the performance of air cleaning 

devices for particles between 0.03 and 0.3 μm. Therefore, 

efforts were focused on testing a wide variety of air cleaning 

devices over the entire 0.03 to 10 μm particle diameter 

range, so that empirical equations could be developed over 

that entire range, rather than just the 0.3 to 10 μm generally 

available in the literature. It should also be noted that the 

objective of this effort was not to determine the “typical” 

performance to be expected of a particular make and model 

of filter, nor to determine the accuracy of the MERV ratings 

supplied by manufacturers. Although some observations 

were made in regard to these two issues, they were not the 

objectives of this effort.)

The research described in this report consisted of four 

phases. In the first phase, representative HVAC air cleaning 

devices were selected for experimental evaluation. In the 

second phase, a pair of Test/QA Project Plans (QAPP) 

were drafted that clearly defined the test methods and 

procedures that were used during testing (Battelle, 2005a; 

Battelle, 2005b). The test protocols were primarily based 

on a commonly used standard, ANSI/ASHRAE Standard 

52.2-1999 (ANSI/ASHRAE, 1999). This standard describes 

a test fixture and methodology for measuring the pressure 

drop and collection efficiency of ventilation filters, as well 

as a method for determining the MERV rating. In the third 

phase, the 27 commonly used air cleaning devices identified 

in Phase 1 were acquired and evaluated for their pressure 

drop and collection efficiency, as received. In addition, 

eight electrostatic filters were subsequently loaded with a 

submicrometer inert aerosol and their collection efficiency 

reevaluated. Ten of the devices (seven filters and three 

EACs) were evaluated for their collection efficiency after 

approximately 1 or 2 weeks, 2 or 4 weeks, 6 or 8 weeks, and 

12 or 16 weeks of normal use. A separate set of ten devices 

(seven filters and three EACs, also known as electrostatic 

precipitators) were evaluated for their efficiency for a 

bioaerosol. Finally, three (EACs) were evaluated both before 

and after exposure to silicon vapor to simulate an actual 

use environment. In the fourth phase, empirical equations 

that related particle collection efficiency to particle physical 

diameter over the range of 0.03 to 10 μm were developed to 

fit the data collected during Phase 3. Each of these phases is 

described in the rest of this report. 

The results of the experimental efforts described in this report 

will help to mitigate the impacts of a terrorist attack with a 

biological threat agent by:

• Providing empirical performance equations of particulate 

collection efficiency that can be used in indoor air quality 

modeling efforts to assess the impact of HVAC particulate 

control devices (used in residential or commercial 

buildings) on reducing the effects and spread of aerosol 

contaminants.

• Providing empirical performance data regarding the 

pressure drop of these air cleaning devices that can be 

used to assess energy requirements of air cleaners during 

building operation.

• Comparing the penetration of inert and biological particles 

through said air cleaning devices.

• Expanding the data set regarding aerosol penetration over 

a wider range of particle sizes.
2

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3

2.0

Air Cleaner Device Selection

2.1 Filter Selection

The first step in the overall effort was to select the air 

cleaning devices for testing. Table 2-1 illustrates the 

recommendations provided in the statement of work 

for the filter test matrix. As shown in Table 2-1, the 

recommendations indicated that only a few filters of 

moderate efficiency (MERV 5–10) be evaluated so that a 

clear comparison between those filters and filters with greater 

efficiencies (charged filters and those with MERVs greater 

than 10) could be made. The recommendations also indicated 

that more attention should be focused on commercial 

HVAC than on residential HVAC filters. It was preferred 

that the filters selected for the biological and in-use tests be 

a subset of those selected for the inert aerosol tests so that 

comparisons among the various results could be made.

Table 2-1. Test Matrix for Filter Evaluation

MERV Range Inert Aerosol Tests In-Use Tests Biological Tests

Residential Filters

5 to 10 inclusive 2a 0 1

11 and higher 3 0 1

Charged filter media 3 2 2

Total 8 2 4

Commercial HVAC Filters

5 to 10 inclusive 2 0 0

11 to 12 inclusive 3 0 0

13 to 15 inclusive 3 1 1

16 3 1 1

HEPA or other >16 3 1 2

Charged filter media 3 2 2

Total 17 5 6

a The total number of test filters with MERV ratings less than or equal to 10 should not exceed 4.
4

Table 2-2 provides a listing of the approximate U.S. 

market share for a variety of filter manufacturers in both 

the residential and commercial markets (McIlvane, 2002). 

As shown in Table 2-2, American Air Filter clearly holds a 

dominant portion of the U.S. air filter market, possessing 

almost a third of the residential market, and is the only 

company to possess more than 10% of all the different filter 

categories. Other manufacturers that hold significant shares 

of the residential market include Flanders, Purolator, and 3M. 

The commercial market is spread much more evenly among 

a larger number of companies, notably American Air Filter, 

Farr, Airguard, and Flanders.

The selection of residential filters to be tested was based on 

the manufacturer’s share of the residential market, previous 

experience with filter evaluations, information available 

on the Web sites of various vendors, an informal survey of 

filters available at retailers such as Home Depot, Lowe’s, and 

Wal-Mart, and telephone conversations with various sales 

representatives. Approximately ten company Web sites were 

thoroughly examined, and various vendors were contacted 

to determine which of their particular air filters were the 

most popular, and to obtain technical information. All of 

the selected filters were commercially available across the 

United States.

From the compiled information, it was apparent that in the 

residential market, the most inexpensive filters dominate. 

These include fiberglass, disposable polyester/cotton blends, 

and pleated air filters. The lowest MERV-rated filter identified 

was 4, and the highest rated filter available in the residential 

market was 12. Electrostatic filters were found to dominate 

the medium- and high-efficiency residential filter market. No 

commercially available non-electrostatic residential filters 

with MERV ratings above 10 were identified.

As shown in Table 2-3, the manufacturer-supplied MERV 

ratings for the tested residential filters ranged from 6 

to 12. Since the residential market was so dominated 

Table 2-2. Approximate Shares of the U.S. Air Filter Market (McIlvaine, 2002)

Company

MERV

1–4 (%)

MERV

5–9 (%)

MERV

10–16+ (%) Total (%)

Residential 

(%)

Commercial 

(%)

American Air Filter 25 12 13 16 32 12

Farr 3 9 6 7 11

Air Guard 3 9 6 7 11

Flanders 18 4 13 10 15 8

McLeod Russel 4 2 4

Purolator 8 4 3 5 10 5

Glas Floss 4 2 4

Koch 3 2 4

Freudenberg 2 1

Air Kontrol 3 2 2 4 2

Donaldson 10 16 8

3M 7 4 11 2

Web Products 2 1 3 <1

Camfil 5 <1

Tridim 3 3 3 3 2 4

Hefco 4 <1

Hepa 6 <1

TDC <1 <1

Pneumafil <1 <1

Fleetguard 6 1

W.L. Gore 6 1

General Filters Inc. 1 <1 2 <1

Columbus 2 4 2 3 1 3

Dollinger 2 1 1

Filtration Group <1 3 1 2 <1 2

BHA <1 <1 <1 <1 <1

Trion 2 1

Viskon-Aire 1 <1 <1

Fiberbond 2 1 2

Others 34 9 9 17 19 21
5

by electrostatic materials (mostly polypropylene and/

or polyolefin), six filters with charged media (rather than 

the three specified in the statement of work [SOW]) were 

evaluated. An option that was discussed but not pursued was 

to evaluate two washable filters, which are fairly common in 

the market but generally have low MERV ratings. All of the 

tested residential filters had a recommended service lifetime 

of three months.

The selection of commercial filters to be tested was also 

based on the manufacturer’s share of the residential market, 

previous experience with filter evaluations, information 

available on the Web sites of various vendors, and 

telephone conversations with various sales representatives. 

Approximately 15 company Web sites were thoroughly 

examined, and various vendors were contacted to determine 

which of their particular air filters were the most popular, 

and to obtain technical information. In addition, an HVAC 

maintenance specialist recommended different types of 

commercial air filters. This specialist stated that the bag or 

box designs performed better and had longer lifetimes than 

pleated or panel type filters, so two bag filters and three box 

filters were included in the recommended test matrix. All of 

the selected filters were commercially available across the 

United States.

As shown in Table 2-4, a much wider variety of filter types 

and MERV ratings are available in the commercial market. 

It was not difficult to find commercial filters with MERV 

ratings between 1 and 15. MERV 16 filters were more 

difficult to find, but three suitable candidates were identified 

with a reasonable amount of effort. As high efficiency 

particulate air (HEPA) filters are highly regulated, are not 

meant to be evaluated by ASHRAE 52.2-1999 (ASHRAE 

52.2-1999), and are generally unsuitable for general HVAC 

usage due to their pressure drop, it was recommended that 

fewer HEPA filters be tested than was recommended in 

the SOW (Table 2-1). Instead, two additional filters with 

MERV ratings between 13 and 15 were added to the matrix. 

As shown in Table 2-4, the MERV ratings for the filters 

recommended for testing ranged from 7 to 16.

It may be important to note that during procurement of the 

commercial filters, a fairly high number of difficulties were 

experienced. Although some mistakes should be expected 

given the significant number of filters and filter types that 

were procured, difficulties in obtaining serviceable filters 

of the correct model and size were experienced with nearly 

one-third of the procured test filters. These difficulties 

included shipment of incorrect (but similar) models, incorrect 

sizes, incorrect frame types and materials, and damaged or 

improperly constructed filters. For consumers concerned with 

filter performance, care must be taken to inspect filters before 

use to ensure that the filters are appropriate for use. Much 

less difficulty was encountered with the procurement of the 

residential filters.

Table 2-3. Evaluated Residential Filters

Required 

MERV 

Ratings 

(from SOW)

Identifier for 

Charts and 

Tables Description

Manufacturer 

MERV Rating

Dimensions 

(inches) Electrostatic

As-Is 

Tests

In-Use 

Tests

Biological 

Tests

5 to 10 

inclusive

IPP-6-1 Pleated polyester and 

cotton blend

6 16 x 25 x 1 No Yes No No

2NS-8-1 Pleated polyester and 

cotton blend

8 16 x 25 x 1 No Yes No Yes

11 and 

higher

3PAF-11-1 Pleasted hydrophobic 

synthetic media

11 16 x 25 x 2 Yes Yes No No

4FUA-12-1 Pleated polypropylene 

and polyolefin

12 16 x 25 x 1 Yes Yes No Yes

5RM-11-1 Pleated electrostatic 11 16 x 25 x 1 Yes Yes No No

Charged 

Filter Media

6DDUE-8 Pleated electrostatic 8 16 x 25 x 1 Yes Yes Yes Yes

7AST-8-3 Pleated electrostatic 8 16 x 25 x 1 Yes Yes No No

8NM-10 Pleated electrostatic 10 16 x 25 x 1 Yes Yes Yes Yes
6

Table 2-4. Evaluated Commercial Filters

Required 

MERV 

Ratings 

(from SOW)

Identifier for 

Charts and 

Tables Description

Manufacturer 

MERV Rating

Dimensions 

(inches) Electrostatic

As-Is 

Tests

In-Use 

Tests

Biological 

Tests

5 to 10 

inclusive

C1APP-7 Pleated uncharged 

novel media prefilter

7 24 x 24 x 2 No Yes No No

C2T90-8 Panel uncharged 

polyester prefilter 

with a light tack

8 24 x 24 x 2 No Yes No No

11 to 12 

inclusive

C3AV-11 Pleated 

microfiberglass box 

filter

11 24 x 24 x 4 No Yes No No

C4FPC-11 Pleated 

microfiberglass

11B 24 x 24 x 12 No Yes No No

C5PSC-11 Pleated 

microfiberglass

13B 24 x 24 x 12 No Yes No No

13 to 15 

inclusive

C6ADP-15 Fiberglass bag filter 

(6 pockets)

14B 24 x 24 x 10 No Yes No No

C7CFER-13 Pleated synthetic 

box filter

14 24 x 24 x 12 Yes Yes No No

C8GZ-13 Pleated synthetic 

box filter

13 24 x 24 x 12 YesA Yes Yes No

C14PCS Pleated 

microfiberglass

14B 24 x 24 x 12 No Yes Yes No

C10CFS-14 Meltblown synthetic 

bag filter (8 pockets)

14 24 x 24 x 15 Yes Yes No No

16 C11GM-16 Pleated 

microfiberglass

16 24 x 24 x 12 No Yes Yes Yes

C12AB-16 Pleated 

microfiberglass

16 24 x 24 x 12 No Yes No No

C13AMG-16 Pleated 

microfiberglass

16 24 x 24 x 12 No Yes No No

HEPA or 

other > 16

C114FA-H Pleated 

microfiberglass

HEPA 24 x 24 x 12 No Yes No No

Charged 

Filter Media

C15AAA-11 Pleated electrostatic 

prefilter

11 24 x 24 x 2 Yes Yes Yes Yes

C16ADP-8A Pleated electrostatic 

prefilter

8 24 x 24 x 2 Yes NoA No No

C17FPP-8 Pleated electrostatic 

prefilter

8 24 x 24 x 2 Yes Yes Yes Yes

A – Ultimately, filter C16ADP-8 was not evaluated, as commercial filter C8GZ-13-1 underwent an additional evaluation instead.

B – MERV rating based on Table E-1 in ASHRAE 52.2-1999
7

2.2 Electronic Air Cleaner Selection

EACs are a commercially available alternative to 

filters for residential air cleaning. Generally, EACs 

are marketed as possessing higher efficiencies 

than residential filters, lower pressure drops, and 

no need for frequent filter replacement. Figure 2-1 

illustrates how air is purified by an electronic air 

cleaner. As dirty air is drawn into the unit, the 

particles pass through an electrostatic field and 

receive an ionized charge. The charged particles 

are then collected on alternatively charged or 

grounded collection plates. Frequently, an afteror post-filter is also marketed to remove odors and/or to 

improve the overall efficiency of the unit. Both the collection 

plates and the ionizing system require cleaning every 1 to 

6 months. Both are typically removable for easy cleaning. 

The prefilters are typically made of an aluminum mesh and 

capture only very large dust particles.

The most common EAC sizes are 16" x 25" and 20" x 25" 

and typically cost between $500 to $800 installed. Residential 

EACs are typically designed for installation directly in the 

HVAC duct as “whole-house” cleaners. Portable units are 

also available for single-room purification (typically referred 

to as room air cleaners). Commercial EACs are commonly 

designed for wall or ceiling mounting. The wall/ceiling 

mounted units are typically designed to treat the air in a 

single room independently from the HVAC system.

Table 2-5 illustrates the recommendations that were provided 

in the SOW for the electronic air cleaner test matrix. As 

with the filter tests, the same EACs (make and model) were 

subjected to the inert aerosol tests, the in-use tests, and the 

biological tests so that direct comparisons could be made. 

Similar to filter selection, the selection of EACs to be 

tested was based on the manufacturer’s share of the 

market, information available on the Web sites of various 

vendors, and telephone conversations with various sales 

representatives. Approximately ten company Web sites were 

thoroughly examined, and various vendors were contacted 

to determine which of their EACs were the most popular, 

and to obtain technical information. Five domestic EAC 

manufacturers were identified: United Air Specialists, Trion, 

Honeywell, Skuttle, and Emerson Climate Technologies. 

According to McIlvaine (2002), two companies stand out 

in the field of EACs. Trion is a leader in both the residential 

and commercial markets, whereas United Air Specialists is a 

leader in the commercial market. Trion has reported annual 

sales of $65 million, of which 23% is attributed to residential 

EACs and 37% comprises commercial EAC sales. Present 

sales are estimated at $44 million for United Air Specialists, 

a division of Clarcor. Nearly 100% of United Air Specialists 

revenue is from the sale of commercial EACs.

From the information acquired, it was clear that the 

residential market greatly dominates the commercial market 

for duct-mounted EACs. Only one duct-mounted unit was 

identified that was marketed to the commercial market, and 

that unit was marketed for both commercial and residential 

use. EACs designed for the commercial market are nearly 

exclusively wall- or ceiling-mounted units. In contrast to the 

commercial market, it was estimated that approximately 10% 

of new homes have duct-mounted EACs (McIlvaine, 2002).

Since it was desired to select EACs that were as 

representative as possible of the overall market, the three 

residential EAC units listed in Table 2-6 were selected 

for evaluation. All three are duct-mounted units that are 

available nationwide.

Figure 2-1. EAC Air Filtration Mechanism

Table 2-5. Recommended Test Matrix for Electronic Air Cleaner Evaluations from the Statement of Work

EAC Tests Inert Aerosol TestsA In-Use Tests Biological Tests

1 unit from 3 vendors 3 3 3

A – Including silicon vapor exposure tests

Table 2-6. Evaluated Electronic Air Cleaners

Identifier for 

Charts and Tables Price ($)

Dimensions 

(inches)

Capacity 

(CFM)

Manufacturer-Provided 

Pressure Drop

Manufacturer-Provided 

Collection Efficiency

A $405 16 x 25 Up to 2000 0.17" w.g. at 500 fpm > 94% at 0.35 μm (MERV 15)

H $283 20 x 20 Up to 1400 0.06" w.g. at 295 fpm Up to MERV 12 at 492 fpm

P $310 20 x 20 Up to 1400 0.11" w.g. at 500 fpm NA

NA = Not available
8

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9

3.0

Experimental Methods

As described in Section 1.0, a variety of different test 

methods were used during this study. For all 24 filters and all 

3 EACs, inert aerosol evaluations were performed to measure 

their “off-the-shelf ” collection efficiency for particles with 

diameters between 0.03 and 10 μm. For a select group of 

seven filters and three EACs, testing using a bioaerosol 

was performed for comparison to the inert aerosol results. 

For a select group of seven filters and three EACs, aging 

was performed in conjunction with inert aerosol testing 

to examine the effect of use on the collection efficiency 

and pressure drop of the units. For a select group of eight 

electrostatic filters, inert aerosol testing was performed in 

conjunction with submicron particle conditioning in the 

ASHRAE 52.2-1999 test rig to evaluate the degradation in 

performance likely to occur with use. For all three EACs, 

inert aerosol testing was performed both before and after 

exposure to silicon vapor to simulate the degradation in 

performance likely to occur during actual use. Filters were 

selected for the bioaerosol and electrostatic tests using the 

recommendations listed in Table 2-1 to ensure that a variety 

of residential and commercial filters and a variety of MERV 

ratings were examined. Descriptions of the various test 

methods used during these evaluations are provided in

turn below.

3.1 Inert Aerosol Tests

The purpose of the inert aerosol tests was to characterize the 

filtration efficiency of the air cleaners for particles between 

0.03 and 10 μm at the maximum flow rate the units would 

likely encounter in actual use. The pressure drops of the units 

were also evaluated at 50%, 75%, 100%, and 125% of the 

maximum flow rates that the units would likely encounter 

in actual use. All testing was performed in accordance with 

ANSI/ASHRAE Standard 52.2-1999 “Method of Testing 

General Ventilation Air-Cleaning Devices for Removal 

Efficiency by Particle Size” (ANSI/ASHRAE, 1999). All of 

the inert aerosol tests were performed by Intertek ETL Semko 

in their certified ASHRAE 52.2-1999 test facility. A detailed 

description of the facility and test procedures required for 

ASHRAE 52.2-1999 testing can be found in the standard 

(ANSI/ASHRAE, 1999) and therefore is not repeated in this 

document. However, for the convenience of the reader, brief 

summaries of the facility and procedures are provided below.

3.1.1 Inert Aerosol Test Method

All of the inert aerosol tests were conducted in Intertek ETL 

Semko’s certified ASHRAE 52.2-1999 test rig. The test 

rig’s fully enclosed ducting is primarily composed of 24" 

x 24" (0.61 x 0.61 m) cross section. The system operates 

at positive pressure to minimize infiltration and has two 

pleated 24" x 24" (0.61 x 0.61 m) prefilters and two 24" x 24" 

(0.61 x 0.61 m) HEPA filters both downstream and upstream 

of the blower to ensure a consistent aerosol challenge to the 

test air cleaner.

As required by ASHRAE 52.2-1999 (ANSI/ASHRAE, 1999), 

to mix the test aerosol with the air stream, an orifice plate 

and mixing baffle are located immediately downstream of 

the aerosol injection point and upstream of the test device. 

An identical orifice plate and mixing baffle are located 

after the 180 degree bend. The latter downstream orifice 

Figure 3-1. Aerosol Sampling Instruments, TSI SMPS (left) and Climet CI-500 (right)
10

straightens out the flow after going around the bend and 

mixes the aerosol that penetrates the air cleaner. This mixing 

is necessary to obtain a representative downstream aerosol 

measurement.

Two particle sizing and counting instruments were used for 

the inert aerosol tests: a Climet model 500 Spectrometer 

OPC covering the particle diameter size range from 0.3 

to 10 μm in 12 particle sizing channels and a TSI SmPS 

covering the range from 0.03 to 0.3 μm (shown in Figure 

3-1). The OPC uses a laser-light illumination source and has 

a wide collection angle for the scattered light. The SmPS 

consisted of a TSI model 3080L electrostatic classifier and a 

TSI model 3022A-S condensation particle counter. It should 

be recognized that the two selected instruments measure 

particles based upon different physical properties: electrical 

mobility in the case of the SmPS and light scattering in the 

case of the OPC. It is well understood in the field of particle 

physics that these two size measurements are not directly 

comparable. This did not affect the efficiency measurements 

for specific particle sizes but was chiefly responsible for the 

minor gaps in continuity that were occasionally observed 

between the filtration efficiency curves obtained from the 

two instruments.

Two aerosol generators were used for the tests. Both used 

an aqueous solution of potassium chloride (KCl) to generate 

particles. The concentration of KCl in the solution was varied 

as needed to generate particles in the proper size range. For 

the 0.3 to 10 μm tests, an external air atomizing nozzle was 

used along with a KCl solution of approximately 300 g KCl 

to 1 liter of distilled water. For the 0.03 to 0.3 μm tests, a 

Collison nebulizer was used with a solution of approximately 

100 g KCl to 1 liter of distilled water. Both generators were 

connected to a 12-inch (0.30 m) diameter, 51-inch (1.3 m) 

tall transparent acrylic spray tower. The tower allowed the 

salt particles to dry as well as the larger particles to settle 

out of the challenge aerosol air stream. After drying in the 

spray tower, the challenge aerosol passed through an aerosol 

neutralizer before being injected counter to the airflow in 

the test duct. This was necessary as aerosol particles have a 

tendency to collect static charge, which may influence their 

filtration characteristics.

As required by ASHRAE 52.2-1999 (ANSI/ASHRAE, 1999), 

the aerosol sampling lines (both upstream and downstream) 

were composed of stainless steel, used gradual bends when 

needed to minimize particle losses, and used changeable 

sampling nozzles to ensure isokinetic sampling at the various 

flow rates. For the 0.3 to 10 μm tests, an automated valve 

system was used to automatically control the upstream and 

downstream sampling by the OPC. For the 0.03 to 0.3 μm 

tests, the sampling lines were manually altered.

It should be noted that the inert aerosol tests consisted of only 

the pressure drop measurements and the initial collection 

efficiency measurements specified in ASHRAE 52.2-1999 

(ANSI/ASHRAE, 1999). ASHRAE 52.2-1999 (ANSI/

ASHRAE, 1999) also describes a procedure for dust loading 

with a standardized loading dust in conjunction with a 

series of collection efficiency tests to examine the collection 

efficiency of the air cleaners as they become loaded with 

dust. At the direction of the sponsor, these loading procedures 

were not performed.

In addition, it also should be noted that the tests of the EACs 

were performed by the procedures described above with only 

one modification. In the case of the EACs, care was taken to 

ensure that the devices were powered and properly operating 

during the tests.

3.1.2 Inert Aerosol Data Analysis

As specified in ANSI/ASHRAE Standard 52.2-1999 (ANSI/

ASHRAE, 1999), the computation of inert aerosol filtration 

efficiency was based on the ratio of the downstream-toupstream particle concentrations corrected on a channel-bychannel basis for:

• Background counts (i.e., upstream and downstream counts 

observed when the aerosol generator is off) 

• The correlation ratio measured at the start of the test 

sequence

These data were used for determining filtration efficiency by 

computing the observed penetration (Pobserved):

(1)

where:

D = Downstream particle count,

Db = Downstream background count,

U = Upstream count, and

Ub = Upstream background count.

As specified in ANSI/ASHRAE Standard 52.2-1999, to 

remove system bias, the observed penetration was corrected 

by the correlation ratio (R) (the Pobserved measured during a 

blank control test for which no filter is installed in the duct).

(2)

The filtration efficiency was then computed as:

Filtration Efficiency (%) = 100 (1-Pcorrected) (3)

Data from the inert aerosol tests were verified to ensure 

that all measured parameters fell within reasonable 

agreement with the anticipated results before continuing/

terminating testing.

A sample set of calculations from the inert aerosol tests is 

provided in Appendix A.

3.2 Bioaerosol Tests

A select group of filters (seven) and EACs (three) were 

evaluated against a bioaerosol. The purpose of the bioaerosol 

tests was to compare the penetration of a bioaerosol to the 

penetration of a similarly sized inert aerosol to determine 

whether there were any significant differences between the 

penetration of bioaerosol and inert particles.
11

3.2.1 Bioaerosol Test Method

The first step in the bioaerosol testing was the selection of 

an organism. The bioaerosol tests were conducted using the 

spore form of the Gram-positive bacteria Bacillus atrophaeus

(formerly B. subtilis var. niger and Bacillus globigii or 

BG). The BG spore is elliptically shaped with dimensions 

of 0.7 – 0.8 x 1 – 1.5 μm. BG spores were used for testing 

because they:

• Have historically been used as a surrogate for 

anthrax spores

• Are very durable

• Possess natural resistance to heat and desiccation

• Are significantly resistant to loss of culturability during 

aerosolization and collection

• Have a median aerodynamic diameter of approximately 

1 μm, thus they possess a reasonably good chance of 

penetration through air cleaning devices

• Can be generated in sufficient concentrations for testing

• Can be generated as single spores with narrow size 

distributions

The BG spore challenge suspensions were prepared using 

a dry Dugway Proving Ground BG powder. The Dugway 

BG was processed post-production. The raw fermentation 

product was concentrated to achieve 20% solids content. The 

concentrated BG suspension was then spray dried. Aerosil 

812 S (Degussa GmbH; Düsseldorf, Germany) was added 

as the dried batches were blended. The dried BG was then 

jet milled and additional Aerosil 812 S was added to achieve 

the desired physical properties. The BG spore challenge 

suspensions were prepared for testing by resuspending 

25 grams of the dry Dugway Proving Ground BG powder 

in 1000 mL sterile 18 megohm/cm water. (Resuspension 

in sterile 18 megohm/cm water is essential to minimize 

the particle counts from sources other than the organisms 

themselves [e.g., dissolved solids].) This stock suspension 

was approximately 5.0 x 109 colony forming units (CFU)/

mL and was used to prepare the nebulization suspension 

for each aerosol test. The nebulization suspension for each 

test was prepared by diluting 20 mL of the stock suspension 

in 180 mL of 18 megohm/cm water, yielding a challenge 

concentration of approximately 5.0 x 108 CFU/mL.

Because the aerosol generation and measurement techniques 

and equipment required for bioaerosol testing were different 

from those required for ASHRAE 52.2-1999, and required a 

higher level of containment and different handling protocols, 

the bioaerosol testing was performed in a separate test facility 

from the inert aerosol testing. A diagram of the bioaerosol 

evaluation test duct is shown in Figure 3-2. The test duct 

possessed an approximately 24" x 24" cross-sectional 

sampling zone where an array of reference samplers and 

the unit being tested were exposed to the same well-mixed 

bioaerosol. The air was pulled through the test system by 

a blower located downstream of a pair of 24" x 24" x 12" 

HEPA filters to ensure bioaerosol containment. A pair of 

24" x 24" x 12" HEPA filters were also used on the intake to 

the test duct to prevent any contamination of the test system 

by background biological materials.

As shown in Figure 3-2, the challenge organism suspensions 

were aerosolized using a single 24-jet Collison nebulizer 

(BGI, Waltham, MA) at 40 pounds per square inch (PSI) 

air pressure. The Collison nebulizer generated droplets 

with an approximate volume mean diameter of 2 μm. 

Since the remaining water evaporated upon exposure to 

the large volume of air (> 800 cfm) moving through the 

test system, the aerodynamic mass median diameter of 

the challenge aerosol was generally less than 1 μm (single 

spores). Upstream and downstream sampling of the aerosol 

was accomplished isokinetically, using nine upstream and 

nine downstream 47-mm water-soluble gelatin filters (18 

total samples). These filters were placed in standard 47-

mm filter housings and connected to the sampling probes. 

(Filter holders and impactors were autoclaved at 121 oC at 

a pressure of approximately 19 PSI for 20 minutes and then 

dried with a 10-minute vacuum exposure at 10 inHg prior 

to testing.) A vacuum pump was used to sample through the 

filters at a rate of approximately 7.5 L/min. Once sampled, 

the filters were removed from their holders, dissolved in 10 

mL of pH 7.4 phosphate-buffered saline (PBS), and then 

diluted to an appropriate concentration before being plated on 

tryptic soy agar (TSA). Each sample was plated in triplicate 

Figure 3-2. Schematic of the Bioaerosol Test Rig
12

and incubated overnight at 32 oC. After the incubation period, 

the colonies were counted using a QcountTM automatic 

plate counter (Spiral Biotech, Inc.), and the colony counts 

were used to calculate the filtration efficiency of the test air 

cleaner.

The size distribution of the challenge aerosol was determined 

using a six-stage Battelle cascade impactor (BCI). The 

cutoff aerodynamic size ranges for Stage 1 to Stage 6 were 

16.0 μm and greater, 16.0 – 8.0, 8.0 – 4.0, 4.0 – 2.0, 2.0 – 

1.0, and 1.0 – 0.5 μm, respectively. Particles collected on 

the filter were smaller than 0.5 μm (the filter was considered 

a seventh stage). The glass impactor slides were coated 

with a thin film of KY Jelly®, a water-soluble adhesive. The 

slides were extracted in 100 mL beakers, using 10 mL of pH 

7.4 PBS with shaking at 32 oC for 10 minutes at a speed of 

120 rpm. The samples were then diluted to an appropriate 

concentration and plated on TSA. Each sample was plated 

in triplicate and incubated overnight at 32 oC. After the 

incubation period, the colonies were counted using the 

QcountTM automatic plate counter, and the colony counts 

were used to calculate the size distribution of the bioaerosol.

The experimental conditions and sampling times were 

adjusted so that these samplers were used within their upper 

and lower sampling limits. To quantify the microbial counts, 

the BG samples were plated according to Battelle’s standard 

operating procedure (SOP), ABAT-E-002-00 Standard 

Operating Procedure for the Operation and Maintenance of 

the Spiral Biotech Autoplate® 4000 Automated Spiral Plater. 

Post-extraction, BG samples were diluted in PBS, using 

serial 10-fold dilutions to achieve concentrations in the range 

of 20 CFU/mL to approximately 10,000 CFU/mL. Samples 

were then plated in triplicate on TSA using the Spiral 

Biotech Autoplate® 4000. This instrument deposits 50 μL of 

sample over the surface of the plate in a spiral pattern with a 

distribution that dilutes the sample, allowing the enumeration 

of samples in the aforementioned range. The plates were 

incubated overnight at 32 oC, and CFU/mL were determined 

by counting the resulting colonies with the Spiral Biotech 

QCountTM colony counter.

Both before the air cleaner tests were conducted and 

during each test, the uniformity of aerosol concentration 

was measured. Both with and without air cleaners present, 

bioaerosol measurements were performed both upstream 

and downstream of the air cleaner test location, at crosssectional planes perpendicular to the flow. The cross-section 

was divided into nine equal areas, and concentration was 

measured at the center of each area. The mean concentration 

and the coefficient of variation (CV, computed as the standard 

deviation divided by the mean) of the nine corresponding 

grid point concentration values was then calculated. The 

maximum acceptable CV value was set at 30%. If the 

measured CV exceeded 30%, the airflow baffles were 

modified, and the test was repeated until the requirement 

of CV less than 30% was met. This uniformity test was 

performed at both flow rates used for the bioaerosol tests 

(820 cfm and 984 cfm).

Similarly, before each bioaerosol test, airflow rates were 

measured using a hot-wire anemometer to measure the air 

velocity at the nine points that were identified in the center 

of the nine equal, imaginary areas across the test duct at the 

inlet location of the air cleaners. The mean flow velocity 

was calculated by averaging the nine velocity values and 

multiplying the mean velocity by the cross-sectional area. 

The CV of the velocities was also calculated. The maximum 

acceptable CV value was set at 25%. If the measured CV 

exceeded 25%, the airflow baffles were modified, and the 

test was repeated until the requirement of CV less than 25% 

was met.

3.2.2 Bioaerosol Data Analysis

Data analysis was performed using commercially available 

software (Microsoft Excel) by manually entering the raw data 

into a spreadsheet and calculating the results from a series 

of equations. Samples were collected simultaneously using 

multiple samplers. 

The mean upstream and downstream concentrations were 

calculated as:

and (4)

where:

Di = Downstream concentration of the ith sample and n 

is the number of samples collected, 

Ui = Upstream concentration of the ith sample and n is 

the number of samples collected,

D = Mean downstream concentration with a unit 

installed in the test rig, and

U = Mean upstream concentration with a unit installed in 

the test rig.

The calculation of the penetration was based on the ratio of 

the downstream to upstream culturable concentrations. The 

penetration with the unit installed in the test rig (Pmeasured) is 

shown in the following equation:

(5)

where:

P measured = Penetration with the unit installed in the

test rig.

The P100 (no unit installed in the test rig) was calculated as 

the Pmeasured but using the results of the no-filter tests.

(6)
13

where:

D100 = Mean downstream concentration with no unit 

in the test rig and

U100 = Mean upstream concentration with no unit in 

the test rig.

To remove system bias, the Pmeasured was corrected by the 

penetration of a blank “no-filter” test for which no air cleaner 

was installed in the duct (P100). (P100 was 0.995 for the 820 

cfm tests and 1.034 for the 984 cfm tests.)

(7)

The filtration efficiency was then calculated as shown in 

Equation 8.

Filtration Efficiency (%) = 100 (1 – Pcorrected) (8)

Lastly, the combined standard deviation of the penetration 

measurements was calculated to indicate one standard 

deviation of the penetration based on the CV of the upstream 

and downstream culturable concentrations as shown in 

Equation 9.

Combined Standard Deviation =

Pmeasured [(CVU)2 + (CVD)2]0.5 (9)

Where:

Pmeasured = Penetration calculated from the upstream and 

downstream culturable concentrations,

CVU = Coefficient of variation from the upstream 

concentrations, and

CVD = Coefficient of variation from the downstream 

concentrations.

A sample set of calculations from the bioaerosol tests is 

provided in Appendix B.

3.3 Aging of Air Cleaners for In-Use Tests

For a select group of seven filters and three EACs, aging 

was performed in conjunction with inert aerosol testing to 

examine the effect of dust loading in actual use environments 

on the collection efficiency and pressure drop of the units.

3.3.1 Aging of Filters

To determine the effects of dust accumulation, a select 

group of seven filters was tested using the inert aerosol 

procedures described in Section 3.1 both before and after 

aging in actual use environments. As shown in Tables 2-3 and 

2-4, two residential filters and five commercial filters were 

evaluated “in-use.” For all seven filters, evaluations using the 

procedures described in Section 3.1 were performed before 

use and then after approximately 2 weeks, 4 weeks, 8 weeks, 

and 12 (residential), or 16 (commercial) weeks of use. It is 

important to note that it was not feasible to use the same filter 

for all five of these evaluations due to the excessive amount 

of shipping and handling that would be required to transport 

the filter between the use environment and the test facility. 

Therefore, five identical (from the same package or lot) filters 

of each of the seven filter types were used during testing.

For the residential filters, aging was accomplished by 

using the filters in the home residences of two Battelle 

staff members. Because of the significant differences in 

the operational parameters of residential HVAC systems, 

electronic data logging systems were installed into each 

residence to record the actual hours of operation of the 

blower. Photographs of the residential HVAC systems used 

are provided in Appendix C.

For the commercial filters, aging was accomplished by 

insertion into two separate operational HVAC systems at 

Battelle’s facilities in Columbus, Ohio, and West Jefferson, 

Ohio. Both of these HVAC systems operated using 100% 

fresh (outdoor) air intake, 24 hours per day, 7 days per week. 

Both of these systems used a pair of filters to process the 

outdoor air — a bank of 24" x 24" x 2" prefilters followed 

by a bank of 24" x 24" x 12" medium- to high-efficiency 

filters. Photographs of the two HVAC systems are provided in 

Appendix C. In both cases, a complete replacement of all the 

filters (both prefilters and medium/high-efficiency filters) in 

the entire filter bank was performed when aging was initiated. 

This was performed to ensure that the flow (and thus the dust 

loading) through the various filters would be as homogenous 

as possible during the entire aging process. All of the aged 

filters were initially inserted into the system on the same 

day. The filters were removed individually, when their aging 

duration had been completed, and replaced with a new filter 

of the same type. Because the maximum recommended 

lifetime for the residential filters was 3 months, the final 

aging duration was limited to 12 weeks instead of the 16 

weeks that was used for the commercial filters.

After the filters were exposed, they were weighed, 

photographed, and placed into special carrying cases that 

were designed to minimize the loss of loaded dust due 

to vibration, shock, or damage during delivery to the test 

facility. The filters were weighed both before and after 

delivery to the test facility to ensure that the loss of loaded 

dust was minimal. Delivery from the aging location to the 

testing location was performed directly by Battelle staff to 

ensure that no damage occurred during transit.

All filters for this study were stored in an indoor, airconditioned environment both prior to and after aging. Each 

filter was numbered using a permanent marker. All of the test 

filters used in this study were inspected before testing/use and 

were found to be free of problems such as holes or defects 

in the media, damage or defects in the frame, and gaps in the 

seals between the medium and frame. Damaged/defective 

filters were not used in any of the tests.

It may be important to note that significant difficulties were 

encountered in acquiring commercial filters for testing that 

did not contain minor or major defects due to a combination 

of manufacturing errors, damage during transit, incorrect 

filter models being sent, etc. Approximately one third of the 

commercial filters required some sort of remedial action to 

ensure that pristine samples of the correct filter model were 
14

acquired. In contrast, acquisition of the residential filters and 

EACs required no remedial action whatsoever. Therefore, 

to ensure that the desired performance level is met, filter 

purchasers should institute a standard practice of carefully 

inspecting each filter that is received. A careful comparison 

between the model numbers on the filters/boxes/purchase 

order should be performed to ensure that the proper filters 

were received. In addition, each filter should be visually 

inspected to ensure that the filter has the proper dimensions 

and gasketing; has no holes, rips, or tears in the medium; and 

is properly sealed (no breaks) to the filter frame. The filters 

should be stored in a clean, dry area away from normal foot 

traffic and rainwater seepage. During installation, care must 

be taken to ensure that the filters are not handled roughly 

or damaged, and that they are properly installed in the filter 

holders with no gaps in the filter assembly and no loose 

or unused clamping or sealing mechanisms. Without these 

procedures, it is likely that filter performance will not match 

the desired values.

3.3.2 Aging of Electronic Air Cleaners

To determine the effects of dust accumulation, three of 

the EACs were tested using the inert aerosol procedures 

described in Section 3.1 both before and after aging in actual 

use environments. For all three units, evaluations using the 

procedures described in Section 3.1 were performed before 

use and then after 1 week (168 hours), 2 weeks (336 hours), 

6 weeks (1,008 hours), and 12 weeks (2,016 hours) of use. In 

contrast to the aged filters, the same unit was used for all five 

of these evaluations.

Due to the size and weight of the units and the difficulty 

and custom nature of installing/removing them into/from a 

residence, it was not feasible to age them in an actual use 

environment separate from the test facility. Therefore, an 

aging system was fabricated and operated in the test facility 

at Intertek ETL Semko. A photograph of the aging system is 

provided in Appendix D. The system consisted of a single 

blower attached to a plenum that was connected to three 

separate ducts. Each duct contained an airflow monitor as 

well as an adjustable damper. When operating, the aging 

system continuously (100% operation, 24 hours per day, 7 

days per week) drew unconditioned air from the test facility 

through the EACs. The airflow monitors were periodically 

monitored and the dampers modified as needed to ensure that 

the airflow through each unit was approximately 295 fpm 

during the entire exposure period. Since the pressure drop 

of the EACs did not significantly change during loading, 

adjustment of the dampers was rarely necessary. Therefore, 

aging of all of the EACs occurred simultaneously.

All the EACs for this study were stored in an indoor, airconditioned environment both prior to and after aging. Each 

unit was numbered using a permanent marker. All of the 

units used in this study were inspected before testing/use and 

were found to be free of problems such as broken ionizing 

wires, unattached connectors, holes or defects in the media 

(for the one unit that had a filter), damage or defects in the 

frame, and gaps in the seals between the cells and frame. 

(While significant difficulties were encountered in acquiring 

commercial filters that did not contain defects, none of the 

EACs that were procured contained any.) However, care was 

taken to ensure that the cells in the air cleaners remained 

operational during both aging and testing, as it was observed 

during initial testing that the electrical connections on some 

of the cleaners could loosen during use, powering down the 

unit and greatly reducing the collection efficiency.

3.4 Conditioning of Electrostatic Filters

For non-electrostatic air filters, collection efficiency and 

pressure drop will be at a minimum prior to any loading/

usage. Once usage begins, their pressure drop and collection 

efficiency will generally increase as particles are loaded 

because the loaded particles increase the resistance to airflow 

as well as create a more torturous path for particles to pass 

through. However, electrostatic filters achieve a relatively 

high collection efficiency at relatively low pressure drops 

by relying heavily on the electrostatic attraction of particles 

to their charged media. It is well known that the collection 

efficiency of electrostatic filters generally decreases after 

being loaded with a small amount of dust. Similar to other 

filters, eventually, the collection efficiency of electrostatic 

filters generally increases with dust loading once a substantial 

dust cake starts to build up on the filter. Therefore, the 

minimum collection efficiency for electrostatic filters 

generally is not at initial use, but at some point between 

initial loading before a substantial dust cake has built up.

Therefore, eight electrostatic filters were evaluated using a 

modified inert aerosol test method (Section 3.1) that involved 

conditioning to identify their minimum collection efficiency, 

rather than their initial collection efficiency. This modified 

inert aerosol test method was performed in accordance with 

the latest recommendation from ASHRAE, namely draft 

Addendum C for ANSI/ASHRAE Standard 52.2-1999.

Essentially, this test method consisted of multiple 

performances of the procedures described in Section 3.1. 

Their collection efficiencies and pressure drops were initially 

measured using the methods described in Section 3.1. 

Following the initial collection efficiency tests, the filters 

were loaded in the ASHRAE 52.2-1999 test rig with 

submicron potassium chloride particles until the CT 

(concentration*time) of the filters was on the order of 3.2*107

(particles*min)/cm3. The collection efficiency of the filters 

was again measured in both the 0.03 to 0.3 and 0.3 to 10 

μm particle diameter ranges, using the methods described 

in Section 3.1. Loading of the filters with additional 

potassium chloride particles was again performed until 

the CT had approximately doubled (approximately 7*107

[particles*min]/cm3). The collection efficiency of the filters 

was again measured in both the 0.03 to 0.3 and 0.3 to 10 μm 

particle diameter ranges. This pattern was repeated until the 

collection efficiency of the filter did not degrade (decrease 

by more than 2% in more than one individual size bin 

between 0.3 and 10 μm) between two successive loadings 

or when the CT reached 1.2*109 (particles*min)/cm3. As 

explained in draft Addendum C of ASHRAE 52.2-1999, the 

purpose of these loading tests is to determine the minimum 

collection efficiency of electrostatic filters, which are known 
15

to initially degrade in collection efficiency with use until 

the built-up dust cake begins to compensate for the loss of 

available electrostatic charge on the filter fibers. (Based on 

previous testing [Hanley and Owen, 2003], a CT of 3.1*108

[particles*min]/cm3 is thought to represent approximately 

3 months of full-time use.)

3.5 Conditioning of Electronic Air Cleaners Using 

Silicon Vapor

In addition to the “in-use” tests described in Section 3.3, 

three EACs were evaluated by the inert aerosol methods 

described in Section 3.1 both before and after exposure to 

silicon vapor. The purpose of the exposure to silicon vapor 

was to compare the results from exposure to silicon vapor 

to the results from the “in-use” tests to determine whether 

the silicon vapor exposure resulted in a realistic assessment 

of their likely performance after one month of actual use. 

The silicon vapor exposure was performed using the draft 

protocol from the EPA ETV program (Hanley et al., 2002). 

The EAC cell (or cells) were placed in a small (16 to 24 ft3) 

chamber equipped with a 12" nominal diameter fan. The 

fan moved air over a small holding pan filled with DOW 

Corning 244 fluid (octamethylcyclotetrasiloxane) and 

through the EAC cell(s). The cell(s) were placed in the 

chamber and energized according to their normal operating 

voltage. The mixing fan was operated for 3 hours with 

the cells off and the chamber sealed; then the cells were 

powered for 8 hours. The cells were then powered down, 

the chamber vented, and the cells removed. The cell(s) 

were replaced in the EAC and the collection efficiency 

measured as described in Section 3.1. Based on limited 

previous testing (Hanley et al., 2002), 8 hours of exposure 

to the silicon vapor approximates one month of full time 

usage. (This conditioning method duration approximation 

is based on testing of one electronic air cleaner in a single 

home over several months [Hanley et al., 2002].) 
16

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17

4.0

Test Results

As described in Section 3, a variety of different test methods 

were used during this study. For both the filters and EACs, 

inert aerosol evaluations were performed to measure their 

collection efficiency for particles with diameters between 

0.03 and 10 μm. For a select group of both filters (seven) and 

EACs (three), testing using a bioaerosol was performed for 

comparison to the inert aerosol results. For a select group of 

both filters (seven) and EACs (three), aging was performed 

in conjunction with inert aerosol testing to examine the 

effect of use on the collection efficiency and pressure drop 

of the units. For a select group of electrostatic filters (eight), 

inert aerosol testing was performed in conjunction with 

conditioning in the ASHRAE 52.2-1999 test rig to evaluate 

the degradation in performance likely to occur with use. For 

a select group of the EACs (three), inert aerosol testing was 

performed both before and after exposure to silicon vapor 

to simulate the degradation in performance likely to occur 

during actual use. Descriptions of the results from these tests 

are provided in turn below.

The results discussed in Section 4.1 include results only from 

tests of air cleaners in their original “off-the-shelf ” condition. 

Section 4.2 contains the measured bioaerosol penetration 

efficiencies for a selected subset of seven unaged filters and 

three EACs. Results after the various aging and conditioning 

steps are discussed in Sections 4.3 and 4.4, respectively. A 

complete listing of the results from the evaluations of each 

“off-the-shelf ” air cleaner is provided in Appendix E. A 

summary of the results is provided for the filters and EACs in 

the following sections. 

4.1 Unaged — “Off-the-Shelf ” — Inert Aerosol 

Evaluations

The purpose of the inert aerosol tests was to characterize the 

filtration efficiency of the air cleaners for particles between 

0.03 and 10 μm at the maximum flow rate the units would 

likely encounter in actual use. The pressure drops of the units 

were also evaluated at 50%, 75%, 100%, and 125% of the 

maximum flow rates that the units would likely encounter 

in actual use. A total of 27 different air cleaning devices (24 

filters, 3 EACs) were evaluated in this manner in their “asreceived” or “off-the-shelf ” condition.

4.1.1 Unaged Filters

Tables 4-1 and 4-2 summarize the results from the “off-theshelf ” evaluations of the residential and commercial filters, 

respectively. As shown in these tables, the measured pressure 

drops of the filters generally corresponded quite well (± 30%) 

to the information provided by the various manufacturers, 

although in a few cases, the measured pressure drops were 

somewhat greater. In terms of collection efficiency, the 

mERV ratings determined from the tests ranged from two 

ratings above to four ratings below the manufacturer’s 

nominal mERV rating. It should be noted that the testing 

performed on the current study did not include the dustloading portion of ANSI/ASHRAE 52.2-1999; therefore, the 

mERV ratings were determined from the initial collection 

efficiency portion of the test only. As noted in Tables 4-1 

and 4-2, some manufacturers did not provide mERV ratings 

so mERV ratings were estimated based on the literature 

provided by the manufacturer and Table E-1 from ANSI/

ASHRAE 52.2-1999 (1999). Lastly, it should be noted that 

the testing during this study consisted of evaluations of single 

filters, so the results may not be representative of typical 

performance. It should be noted that the purpose of this study 

was not to evaluate manufacturer-provided mERV ratings. 

The results listed in Tables 4-1 and 4-2 are provided to 

illustrate that the obtained results were reasonably similar to 

the anticipated performance based on the obtained literature. 

Since some variation should be expected in individual filters, 

some number of replicates would have been needed to make 

these comparisons statistically meaningful.

Figures 4-1 through 4-18 graphically illustrate the collection 

efficiencies and pressure drops that were measured for the 

“off-the-shelf ” filters. The results from the measurements 

were compiled onto the various charts according to the 

mERV ratings that were obtained. As shown in Figures 4-1 

through 4-18, except for the mERV 8 filters shown in 

Figure 4-7, the collection efficiency curves obtained for the 

filters with identical mERV ratings were similar in shape. 

In addition, collection efficiencies measured with the OPC 

(0.3 to 10 μm) generally corresponded very well with the 

collection efficiencies measured with the SmPS (0.03 to 

0.3 μm), in the common region of overlap around 0.3 μm, 

with only a few discontinuities. 
18

Table 4-1. Results from the Inert Aerosol Evaluations of “Off-the-Shelf” Residential Filters

Required 

MERV 

Ratings 

(from SOW)

Identifier 

for Charts 

and Tables Description Electrostatic

MERV Rating 

(literature)

MERV Rating 

(testing)

MERV

Efficiencies (%)

E1 – 0.3-1.0 μmE2 – 1.0-3.0 μm

E3 – 3.0-10 μm

Literature 

Pressure Drop 

(in. w.g.)

Measured 

Pressure Drop 

(in. w.g.) Notes

5 to 10 

inclusive

IPP-6-1 Pleated 

polyester and 

cotton blend

No 6 5 E1= 5.8

E2= 33.0E3= 33.3

0.18 at 819 cfm 0.18 at 833 cfm MERV 6 requires E3 

> 35%

2NS-8-1 Pleated 

polyester and 

cotton blend

No 8 6 E1= 5.9

E2= 15.7E3= 41.3

NA 0.19 at 820 cfm MERV 7 requires E3 

> 50%

11 and 

higher

3PAF-11-1 Pleasted 

hydrophobic 

synthetic 

media

Yes 11 8 E1= 23.3

E2= 37.9E3= 82.1

0.2 at 850 cfm 0.18 at 820 cfm MERV 9 requires E3 

> 85%. Reported dust 

spot efficiency matches 

MERV 9.

4FUA-12-1 Pleated 

polypropylene 

and polyolefin

Yes 12 12 E1= 39.7

E2= 80.8E3= 92.1

NA 0.09 at 820 cfm None

5RM-11-1 Pleated 

electrostatic

Yes 11 7 E1= 19.2

E2= 64.9E3= 68.7

0.12 at 694 cfm 0.25 at 820 cfm MERV 8 requires E3 

> 70%

Charged 

Filter Media

6DDUE-8 Pleated 

electrostatic

Yes 8 7 E1= 20.6

E2= 51.9E3= 56.8

0.17 at 820 cfm 0.14 at 820 cfm MERV 8 requires E3 

> 70%

7AST-8-3 Pleated 

electrostatic

Yes 8 7 E1= 19.0

E2= 62.6 E3= 61.3

NA 0.29 at 820 cfm MERV 8 requires E3 

> 70%

8NM-10 Pleated 

electrostatic

Yes 10 12 E1= 31.2

E2= 82.4E3= 91.4

NA 0.43 at 820 cfm High pressure drop

NA – Not available
19

Table 4-2. Results from the Inert Aerosol Evaluations of “Off-the-Shelf” Commercial Filters

Required 

MERV 

Ratings 

(from 

SOW)

Identifier 

for Charts 

and Tables Description Electrostatic

MERV Rating 

(literature)

MERV Rating 

(testing)

MERV

Efficiencies (%)

E1 – 0.3-1.0 μmE2 – 1.0-3.0 μm

E3 – 3.0-10 μm

Literature 

Pressure Drop 

(in. w.g.)

Measured 

Pressure Drop 

(in. w.g.) Notes

5 to 10 

inclusive

C1APP-7 Pleated 

uncharged novel 

media prefilter

No 7 6 E1= 4.4

E2= 24.3E3= 49.7

0.28 at 2000 cfm 0.28 at 1968 cfm MERV 7 requires E3 

> 50%

C2T90-8 Panel uncharged 

polyester prefilter 

with a light tack

No 8 7 E1= 15.0

E2= 44.9E3= 51.4

0.50 at 2000 cfm 0.41 at 1968 cfm MERV 8 requires E3 

> 70%

11 to 12 

inclusive

C3AV-11 Pleated 

microfiberglass 

box filter

No 11 10 E1= 34.3

E2= 61.5E3= 92.5

0.45 at 2000 cfm 0.46 at 1968 cfm MERV 11 requires E2 

> 65%

C4FPC-11 Pleated 

microfiberglass

No 11B 8 E1= 25.7

E2= 43.7E3= 78.9

0.30 at 2000 cfm 0.36 at 1968 cfm MERV 9 requires E3 

> 85%

C5PSC-11 Pleated 

microfiberglass

No 13B 12 E1= 59.8

E2= 83.6E3= 97.2

0.60 at 2000 cfm 0.64 at 1968 cfm MERV 13 requires E2 

> 90%

13 to 15 

inclusive

C6ADP-15 Fiberglass bag 

filter

(6 pockets)

No 14B 14 E1= 82.1

E2= 98.1E3= 99.4

1.48 at 2000 cfm 1.68 at 1968 cfm Excessive pressure 

drop was measured 

because tested filter 

was designed for only 

1/3 of the test flow 

rate.

C7CFER-13 Pleated synthetic 

box filter

Yes 14 14 E1= 81.1

E2= 96.8E3= 99.8

0.58 at 2000 cfm 0.85 at 1968 cfm MERV 15 requires E1 

> 85%

C8GZ-13 Pleated synthetic 

box filter

YesA 13 12, 14A E1= 69.4, 77.5A

E2= 88.3, 96.3AE3= 98.6, 98.7A

0.44 at 2000 cfm 0.59, 0.63A at 

1968 cfm

MERV 13 requires 

E2 > 90%, MERV 14 

requires E1 > 75%

C14PCS Pleated 

microfiberglass

No 14B 12 E1= 71.3

E2= 89.4E3= 98.6

0.60 at 2000 cfm 0.60 at 1968 cfm MERV 13 requires E2 

> 90%

C10CFS-14 Melt-blown 

synthetic bag filter

(8 pockets)

Yes 14 14 E1= 81.0

E2= 95.0E3= 98.9

0.50 at 2000 cfm 

(for filter with 12 

pockets)

0.57 at 1968 cfm MERV 15 requires E1 

> 85%
20

Table 4-2. Results from the Inert Aerosol Evaluations of “Off-the-Shelf” Commercial Filters (Continued)

Required 

MERV 

Ratings 

(from 

SOW)

Identifier 

for Charts 

and Tables Description Electrostatic

MERV Rating 

(literature)

MERV Rating 

(testing)

MERV

Efficiencies (%)

E1 – 0.3-1.0 μmE2 – 1.0-3.0 μm

E3 – 3.0-10 μm

Literature 

Pressure Drop 

(in. w.g.)

Measured 

Pressure Drop 

(in. w.g.) Notes

16 C11GM-16 Pleated 

microfiberglass

No 16 16 E1= 98.6

E2= 99.9

E3= 100

0.61 at 2000 cfm 0.85 at 1968 cfm High-capacity unit was 

tested. 95% DOP filter

C12AB-16 Pleated 

microfiberglass

No 16 16 E1= 98.0

E2= 99.7E3= 99.9

0.95 at 2000 cfm 1.01 at 1968 cfm 95% DOP filter

C13AMG-16 Pleated 

microfiberglass

No 16 16 E1= 96.4

E2= 96.8E3= 97.5

0.95 at 1900 cfm 1.29 at 1968 cfm 95% DOP filter

HEPA or 

other > 16

C114FA-H Pleated 

microfiberglass

No HEPA 16+ E1= 100

E2= 100E3= 100

1.45 at 2000 cfm 1.34 at 1968 cfm HEPA filter

Charged 

Filter 

Media

C15AAA-11 Pleated 

electrostatic 

prefilter

Yes 11 7, 8C E1= 41.1, 47.5C

E2= 71.9, 72.9CE3= 66.6, 71.4C

0.38 at 2000 cfm 

(500 fpm)

0.34 at 1968 

cfm, 0.40 at 984 

cfm (492 fpm)C

Tested a 24" x 24" x 2" 

and a 12" x 24" x 2"C

C16ADP-8A Pleated 

electrostatic 

prefilter

Yes 8 NA NA NA NA NA

C17FPP-8 Pleated 

electrostatic 

prefilter

Yes 8 8, 7C E1= 48.3, 39.1C

E2= 91.1, 75.5CE3= 81.3, 64.7C

0.30 at 2000 cfm 

(500 fpm)

0.44 at 1968 

cfm,

0.55 at 984 cfm 

(492 fpm)C

Tested a 24" x 24" x 2" 

and a 12" x 24" x 2"C

A – Ultimately, filter C16ADP-8 was not evaluated, as commercial filter C8GZ-13-1 underwent an additional evaluation instead.B – MERV rating based on Table E-1 in ASHRAE 52.2-1999C – Tested both a 24" x 24" x 2" and a 12" x 24" x 2" filterNA – Not available
21

Figure 4-1. Measured Collection Efficiencies of Unaged MERV 5 Filters

Figure 4-2. Measured Pressure Drops of Unaged MERV 5 Filters
22

Figure 4-3. Measured Collection Efficiencies of Unaged MERV 6 Filters

Figure 4-4. Measured Pressure Drops of Unaged MERV 6 Filters
23

Figure 4-5. Measured Collection Efficiencies of Unaged MERV 7 Filters

Figure 4-6. Measured Pressure Drops of Unaged MERV 7 Filters
24

Figure 4-7. Measured Collection Efficiencies of Unaged MERV 8 Filters

Figure 4-8. Measured Pressure Drops of Unaged MERV 8 Filters
25

Figure 4-9. Measured Collection Efficiencies of Unaged MERV 10 Filters

Figure 4-10. Measured Pressure Drops of Unaged MERV 10 Filters
26

Figure 4-11. Measured Collection Efficiencies of Unaged MERV 12 Filters

Figure 4-12. Measured Pressure Drops of Unaged MERV 12 Filters
27

Figure 4-13. Measured Collection Efficiencies of Unaged MERV 14 Filters

Figure 4-14. Measured Pressure Drops of Unaged MERV 14 Filters (Use of C6-ADP-15-1 data 

is not recommended as filter was used well beyond its recommended flow rate.)
28

Figure 4-15. Measured Collection Efficiencies of Unaged MERV 16 Filters

Figure 4-16. Measured Pressure Drops of Unaged MERV 16 Filters
29

Figure 4-17. Measured Collection Efficiency of Unaged MERV 16+ (HEPA) Filter

Figure 4-18. Measured Pressure Drop of Unaged MERV 16+ (HEPA) Filter
30

The most penetrating particle size was consistently in the 0.1 

to 0.3 μm range, consistent with typical filtration efficiency 

curves. The pressure drops of the filters between MERV 5 

and 8 did not appear to be substantially different, averaging 

approximately 0.18 inches of water at 300 fpm for all four 

MERV ratings. However, the pressure drops of the filters 

generally increased as the MERV ratings increased past 8, 

averaging approximately 0.22 inches of water at 300 fpm for 

MERV 10, approximately 0.34 inches of water at 300 fpm for 

MERV 12 (with the exception of electrostatic filter 4FUA12-1), approximately 0.39 inches of water at 300 fpm for 

MERV 14 (excluding filter C6-ADP-15-1, which was tested 

well beyond its recommended flow rate), approximately 0.57 

inches of water at 300 fpm for MERV 16, and approximately 

0.75 inches of water at 300 fpm for the HEPA filter. 

Therefore, consumers of air filters will need to balance the 

higher pressure drops and costs of MERV 12 to MERV 16 

filters versus the expected increase in performance.

4.1.2 Unaged Electronic Air Cleaners

Table 4-3 summarizes the results from the “off-the-shelf ” 

evaluations of the EACs. As shown in Table 4-3, the 

measured pressure drops of Units A and P corresponded well 

with the information provided by the manufacturers, while 

the pressure drop for Unit H was nearly double the expected 

value. However, in all three cases, the measured pressure 

drops were less than 0.12 inches of water at 295 feet per 

minute, which was approximately one-third less than the 

pressure drops for MERV 5 to 8 filters. In terms of collection 

efficiency, the MERV ratings that were determined from the 

tests ranged from one MERV rating below to three MERV 

ratings above the manufacturer data. The MERV ratings 

were also consistent between the two samples of each unit 

evaluated. As with the filter testing, it should be noted that 

the testing performed on the current study did not include the 

dust-loading portion of ANSI/ASHRAE 52.2-1999; therefore, 

the MERV ratings were determined from the initial collection 

efficiency portion of the test only. Similarly, while the testing 

during this study consisted of evaluating pairs of the units, 

the results may not be representative of typical performance. 

Figures 4-19 and 4-20 graphically illustrate the collection 

efficiencies and pressure drops that were measured for 

the “off-the-shelf ” EACs. As shown in Figure 4-19, the 

collection efficiency curves obtained for the EACs were quite 

similar in shape. In addition, collection efficiencies measured 

with the OPC (0.3 to 10 μm) generally corresponded very 

well with the collection efficiencies measured with the SMPS 

(0.03 to 0.3 μm). As shown in Figure 4-20, the pressure 

drops of the EACs were generally similar or up to 33% less 

than filters with MERV ratings between 5 and 8. Given that 

the EACs possessed MERV ratings of 14 and 15, at least 

initially, they appeared to offer considerably higher collection 

efficiency than air filters for a given pressure drop.

Figure 4-19. Measured Collection Efficiency of Unaged Electronic Air Cleaners
31

Table 4-3. Results from the Inert Aerosol Evaluations of “Off-the-Shelf” Electronic Air Cleaners (Two units of Each Type were Tested)

Identifier for 

Charts and Tables

Dimensions 

(inches) Capacity (CFM)

MERV Rating 

(literature)

MERV Rating 

(testing)a

MERV Efficiencies (%)

E1 - 0.3-1.0 μm

E2 – 1.0-3.0 μm

E3 – 3.0-10 μm

Literature 

Pressure Drop 

(in. w.g.)

Measured 

Pressure Drop 

(in. w.g.) Notes

A 16 x 25 Up to 2000 > 94% at 0.35 μm (MERV 15) 15, 14 E1= 90.8, 84.2 E2= 94.4, 93.1 E3= 96.6, 97.9 0.17 at 500 fpm 0.11 and 0.12 at 295 fpm MERV 15 requires E1 > 85%

H 20 x 20 Up to 1400 Up to MERV 12 at 492 fpm 15, 15 E1=91.5, 92.7 E2= 97.2, 96.9 E3= 98.8, 98.1 0.06 at 295 fpm 0.11 and 0.11 at 295 fpm MERV 16 requires E1 > 95%

P 20 x 20 Up to 1400 none 14, 14

E1= 82.5, 84.0E2= 95.3, 95.1E3= 96.9, 97.1

0.11 at 500 fpm 0.08 and 0.06 at 295 fpm MERV 15 requires E1 > 85%

(a) Two units tested.
32

Figure 4-20. Measured Pressure Drops of Unaged Electronic Air Cleaners

4.2 Bioaerosol Penetration

A select group of filters (seven) and EACs (three) were 

evaluated against a bioaerosol challenge. The purpose of 

the bioaerosol tests was to compare the penetration of a 

bioaerosol to the penetration of a similarly sized inert aerosol 

to determine whether there were any significant differences 

between the penetration of bioaerosol and inert particles.

All of the bioaerosol tests were performed at the same airflow 

rate as the inert aerosol tests, which was the maximum flow 

rate the units would likely encounter in actual use. The 

pressure drops of the devices were also evaluated at the test 

flow rate. For filter 2NS-8-1, the same filter was used for both 

the inert and bioaerosol tests. However, for the remaining air 

cleaners, use of the same device was not feasible. Therefore, 

a unit of the same make, model, and size was used for both 

the bioaerosol and inert aerosol. (For one filter, C11GM16-BIO, a 12" x 24" x 12" filter was evaluated versus the 

bioaerosol, while a 24" x 24" x 12" filter was used in the inert 

particle evaluations. However, the same filtration velocity of 

492 fpm was used.) No aging or conditioning of the filters or 

the EACs was performed prior to the bioaerosol evaluations 

so that direct comparisons to the inert aerosol evaluations of 

“off-the-shelf ” units (Section 4.1) could be made. A complete 

listing of the results from these evaluations for each air 

cleaner is provided in Appendix F. A summary of the results 

is provided below.

Table 4-4 summarizes the results from the bioaerosol tests. 

For the convenience of the reader, both the filter evaluations 

and EAC evaluations are included. As shown in Table 4-4, 

the bioaerosol was consistently aerosolized chiefly as single 

spores, with mass median aerodynamic diameters just under 

1 μm. (The standard deviations measured for the bioaerosol 

indicated that the majority of the bioaerosol particles 

possessed aerodynamic diameters within a factor of two 

of the mass median aerodynamic diameter.) Figures 4-21 

through 4-30 provide a graphical comparison between the 

inert aerosol and bioaerosol test results. In each figure, the 

bioaerosol collection efficiency is plotted along with the 

standard deviation of the bioaerosol particle diameter and the 

standard deviation of the measured collection efficiency as 

calculated using equation 9 from Section 3.2.

Similar to previously reported results (RTI, 2004), in nine

of the ten tests, the measured bioaerosol collection 

efficiencies generally exceeded the average collection 

efficiency for inert particles with physical particle diameters 

between 0.3 and 1 μm (E1) but were generally less than or 

equivalent to the inert aerosol collection efficiency results 

for 1 to 3 μm particles (E2). These results are consistent 

with the measured mass median aerodynamic diameters of 

the bioaerosol. The only exception was filter 6DDUE-8, 

for which a low (6%) bioaerosol collection efficiency was 

measured. However, as shown in Figure 4-24, when the 

standard deviation of the bioaerosol results for filter 6DDUE8 is taken into consideration, the test results are likely in 

reasonable agreement. Overall, the results indicate that 

bioaerosol particles are collected similarly to comparably 

sized inert particles.
33

Table 4-4. Summary of the Results from the Bioaerosol Evaluations

Air Cleaner Description

Air Velocity 

Coefficient of 

Variance

Aerosol 

Concentration 

Coefficient 

of Variance

Mass Median 

Aerodynamic Particle 

Size in μm (geometric 

standard deviation)

Correlation Coefficient 

or Collection Efficiency 

and Combined Standard 

Deviation of Penetration

MERV Efficiencies (%)

From inert evaluations 

E1 - 0.3-1.0 μm

E2 – 1.0-3.0 μm

E3 – 3.0-10 μm Upstream Downstream

None (820 cfm) NA 19.4% 10% 7% 0.71 (2.2) 0.995 NA

2NS-8-1 Pleated polyester and 

cotton blend – residential

18.1% 14% 16% 0.86 (2.1) 14 ± 18% E1= 5.9

E2= 15.7E3= 41.3

4FUA-12-1 Pleated polypropylene 

and polyolefin 

electrostatic – residential

20.8% 10%a 27%a 0.92 (2.0) 50 ± 14%a E1= 39.7

E2= 80.8E3= 92.1

8NM-10-1 Pleated electrostatic – 

residential

25.4% 9% 6% 0.95 (2.1) 40 ± 6% E1= 31.2

E2= 82.4E3= 91.4

6DDUE-8-12 Pleated electet – 

residential

21.0% 13% 16% 0.72 (2.2) 6 ± 19% E1= 20.6

E2= 51.9E3= 56.8

EAC Model A EAC 17.8% 28% 115%b 0.70 (2.2) 93 ± 8% E1e= 90.8, 84.2

E2e= 94.4, 93.1E3e= 96.6, 97.9

EAC Model H EAC 21.2% 21% 57%b 0.81 (2.1) 89 ± 7% E1e=91.5, 92.7

E2e= 97.2, 96.9E3e= 98.8, 98.1

EAC Model P EAC 18.6% 18% 68%b 0.71 (2.1) 95 ± 4% E1e= 82.5, 84.0

E2e= 95.3, 95.1E3e= 96.9, 97.1

None (984 cfm) NA 19.5% 15% 9% 0.82 (2.1) 1.034 NA

C15AAA-11-BIOc Pleated electrostatic 

prefilter – commercial

16.7% 11% 4% 0.99 (2.1) 62 ± 4%c E1= 47.5c, 41.1d

E2= 72.9c, 71.9dE3= 71.4c, 66.6d

C17FPP-8-BIOc Pleated electrostatic 

prefilter – commercial

23.5% 15% 9% 0.86 (2.0) 41 ± 11%c E1= 39.1c, 48.3d

E2= 75.5c, 91.1dE3= 64.7c, 81.3d

C11GM-16-BIOc 5% DOP Pleated 

microfiberglass – 

commercial

19.5% 13% 52%b 0.64 (2.2) 99.8 ± 0.1%c E1= 98.6d

E2= 99.9dE3= 100d

a One sample point was excluded because it differed by at least an order of magnitude (statistical outlier).b Downstream results demonstrated a high CV because the concentrations were very low, and for some samples approaching the detection limit of the analytical method.c Test filter had a 12" x 24" cross section and a flow rate of 984 cfm was used (492 fpm).d Test filter had a 24" x 24" cross section and a flow rate of 1968 cfm was used (492 fpm).e Two EACs of each type were evaluated using inert particles.
34

Figure 4-21. Comparison Between Bioaerosol Collection Efficiency and Inert Collection 

Efficiency Measurements for Filter 2NS-8-1

Figure 4-22. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency 

Measurements for Filter 4FUA-12-1
35

Figure 4-23. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency 

Measurements for Filter 8NM-10-1

Figure 4-24. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency 

Measurements for Filter 6DDUE-8-12
36

Figure 4-25. Comparison Between Bioaerosol Collection Efficiency and Inert Collection 

Efficiency Measurements for Electronic Air Cleaner A

Figure 4-26. Comparison Between Bioaerosol Collection Efficiency and Inert Collection 

Efficiency Measurements for Electronic Air Cleaner H
37

Figure 4-27. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency 

Measurements for Electronic Air Cleaner P

Figure 4-28. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency 

Measurements for Filter C15AAA-11-BIO
38

Figure 4-29. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency 

Measurements for Filter C17FPP-8-BIO

Figure 4-30. Comparison Between Bioaerosol Collection Efficiency and Inert Collection Efficiency 

Measurements for Filter C11GM-16-BIO
39

4.3 Results from the Aging Evaluations

For a select group of both filters (seven) and EACs (three), 

aging was performed in conjunction with inert aerosol 

testing to examine the effect of dust loading in actual use 

environments on the collection efficiencies and pressure 

drops of the units. All of the inert aerosol tests of the aged 

units were performed at the same airflow rate, which was the 

maximum flow rate the units would likely encounter in actual 

use. The pressure drops of the devices were also evaluated at 

the test flow rate. A complete listing of the results from these 

evaluations for each air cleaner is provided in Appendix G. A 

summary of the results is provided for the filters and EACs in 

the following sections. 

4.3.1 Aging Evaluations – Filters

Table 4-5 summarizes the results from the filter aging 

evaluations. Figures 4-31 through 4-44 provide graphic 

illustrations of the test results. It should be noted that 

individual filters were evaluated at each of the different 

loading durations, so some of the variation in the pressure 

drops and collection efficiencies can be attributed to the 

variability in the performance of individual filters. For the 

two electrostatic residential filters (6DDUE-8 and 8NM-10), 

the collection efficiency for larger particles (3.0 to 10.0 μm) 

either increased significantly (6DDUE-8) or remained the 

same (8NM-10) after the filters started to be loaded with 

particles. However, for both filters, a substantial decrease 

in collection efficiency was noted for smaller particles 

(0.3 to 3 μm) after the filters were loaded. The collection 

efficiency of the filters for smaller particles did not exceed 

the initial efficiency until between 8 and 12 weeks of loading 

had occurred. The pressure drops of both residential filters 

remained fairly consistent through the first 8 weeks of 

use but then increased greatly between weeks 8 and 12. It 

should be noted that 12 weeks of use constitutes 100% of the 

manufacturer-recommended service time for these two filters.

The two electrostatic commercial prefilters (C17FPP-8 and 

C15AAA-11) demonstrated consistent average collection 

efficiencies over the entire 16-week aging duration for 

larger particles (4.0 to 10.0 μm). However, as can be 

seen in Figures 4-35 and 4-37, the shape of the collection 

efficiency curve for the unloaded filters (0 week) differed 

from the shape of the curve for the loaded filters. The shape 

of the 0 week collection efficiency curves is not unusual for 

unloaded filters, although it is generally more frequently 

observed with lower-efficiency filters (see Figures 4-1, 4-3, 

4-5, 4-21, and 4-31 for examples). As with the residential 

electrostatic filters, there was a very substantial drop in 

collection efficiency for particles smaller than approximately 

4 μm once the loading began, and the collection efficiency 

for the smaller particles never returned to the measured 

initial values. The pressure drops of the prefilters did not 

demonstrate any noticeable increase over the aging period. 

It should be noted that the typical service life for prefilters 

in the HVAC system of interest ranges from 3 to 6 months, 

so the 4 months of aging that was performed represented 

between 67% and 133% of a typical service period. It should 

also be noted that the performance of filter C15AAA-11 

was considerably poorer than was expected from the 

manufacturer’s literature.

In contrast, the 12-inch deep electrostatic commercial 

box filter (C8GZ-13) substantially degraded in collection 

efficiency for all particle sizes over the entire aging period, 

dropping steadily from MERV 12 to MERV 10. No change 

in pressure drop occurred over this period, implying that a 

suitable dust cake did not form during loading, which would 

likely have caused the degradation of collection efficiency to 

slow. It should be noted that the typical service life for filter 

C8GZ-13 in the application of interest is 6 to 12 months, 

typically closer to 12 months, so the aging period represented 

only 33% to 67% of the typical service life.

As expected, the two commercial, 12-inch deep, nonelectrostatic, traditional fiberglass media deep-pleated 

filters (C14PCS and C11GM-16) did not demonstrate any 

degradation in collection efficiency during the aging period. 

In fact, the collection efficiency of C14PCS clearly increased 

as dust was collected on the filter during aging. No change 

in pressure drop was noted over the aging period for these 

two filters. The typical service life for these two filters in the 

application of interest is 6 to 12 months, typically closer to 

12 months, so the aging period represented only 33% to 67% 

of the typical service life.
40

Table 4-5. Summary of the Results from the Filter Aging Evaluations

Filter Description Electrostatic

MERV 

Rating 

(literature)

MERV Rating 

from testing 

(Hours of HVAC 

Operation)

Average Collection Efficiencies 

(%) Approximate 

Mass of Dust 

Collected 

(grams)

Literature 

Pressure Drop

(in. w.g.)

Measured 

Pressure Drop 

(in. w.g.) Notes

E1 

0.3–1.0 

μm

E2 

1.0–3.0 

μm

E3

3.0–10 

μm

6DDUE–8 Pleated electet 

(residential)

Yes 8 7 (0 weeks – 0 

hours)

20.6 51.9 56.8 0 0.17 at 295 

fpm

0.14 at 295 fpm 

(0 weeks)

NA

8 (2 weeks – 

199 hours)

7.3 25.8 75.3 1 0.16 at 295 fpm 

(2 weeks)

9 (4 weeks – 

544 hours)

12.1 38.3 87.6 8 0.23 at 295 fpm 

(4 weeks)

7 (8 weeks – 

1,040 hours)

4.5 35.6 67.2 7 0.19 at 295 fpm 

(8 weeks)

10 (12 weeks – 

1,307 hours)

11.0 64.5 93.2 5 0.26 at 295 fpm 

(12 weeks)

8NM–10 Pleated 

electrostatic 

(residential)

Yes 10 12 (0 weeks – 0 

hours)

31.2 82.4 91.4 0 NA 0.43 at 295 fpm 

(0 weeks)

NA

10 (2 weeks – 

250 hours)

19.5 59.3 92.1 2 0.50 at 295 fpm 

(2 weeks)

11 (4 weeks – 

450 hours)

27.2 66.6 93.8 1 0.58 at 295 fpm 

(4 weeks)

11 (8 weeks – 

892 hours)

18.1 69.4 91.2 3 0.49 at 295 fpm 

(8 weeks)

13 (12 weeks – 

1,272 hours)

65.6 90.9 93.4 9 1.75 (12 weeks)

C17FPP–8 Pleated 

electrostatic 

prefilter 

(commercial)

Yes 8 7 (0 weeks – 0 

hours) – 12 x 

24 x 2

39.1 75.5 64.7 0 0.30 at 500 

fpm

0.55 at 492 fpm 

(0 weeks)

None

8 (0 weeks – 0 

hours)

48.3 91.1 81.3 0 0.44 at 492 fpm 

(0 weeks)

8 (2 weeks – 

336 hours)

4.7 27.3 70.8 8 0.45 at 492 fpm 

(2 weeks)

8 (4 weeks – 

672 hours)

4.7 25.6 72.5 20 0.45 at 492 fpm 

(4 weeks)

8 (8 weeks – 

1,344 hours)

8.6 31.0 75.8 38 0.47 at 492 fpm 

(8 weeks)

8 (16 weeks – 

2,688 hours)

3.8 30.3 74.9 82 0.57 at 492 fpm 

(16 weeks)
41

Table 4–5. Summary of the Results from the Filter Aging Evaluations (Continued)

Filter Description Electrostatic

MERV 

Rating 

(literature)

MERV Rating 

from testing 

(Hours of HVAC 

Operation)

Average Collection Efficiencies 

(%) Approximate 

Mass of Dust 

Collected 

(grams)

Literature 

Pressure Drop

(in. w.g.)

Measured 

Pressure Drop 

(in. w.g.) Notes

E1 

0.3–1.0 

μm

E2 

1.0–3.0 

μm

E3

3.0–10 

μm

C15AAA–11 Pleated 

electrostatic 

prefilter 

(commercial)

Yes 11 8 (0 weeks – 0 

hours) – 12 x 

24 x 2

47.5 72.9 71.4 0 0.38 at 500 

fpm

0.40 at 492 fpm 

( 0 weeks)

Collection 

efficiency 

was well 

below 

expected 

values.

7 (0 weeks – 0 

hours) 

41.1 71.9 66.6 0 0.34 at 492 fpm 

( 0 weeks)

7 (2 weeks – 

336 hours)

11.0 26.8 66.0 13 0.37 at 492 fpm 

(2 weeks)

7 (4 weeks – 

672 hours)

10.3 25.3 62.0 24 0.38 at 492 fpm 

(4 weeks)

7 (8 weeks – 

1,344 hours)

3.3 21.7 63.6 42 0.39 at 492 fpm 

(8 weeks)

7 (16 weeks – 

2,688 hours)

6.3 26.0 66.7 89 0.46 at 492 fpm 

(16 weeks)

C8GZ-13 Pleated 

synthetic 

box filter 

(commercial)

Yes 13 12 (0 weeks – 0 

hours)

69.4 88.3 98.6 0 0.44 at 500 

fpm

0.59 at 492 fpm 

(0 weeks)

Collection 

efficiency 

degraded 

over entire 

aging period.

11 (2 weeks – 

336 hours)

46.0 73.3 96.6 9 0.59 at 492 fpm 

(2 weeks)

11 (4 weeks – 

672 hours)

38.7 68.2 96.2 14 0.57 at 492 fpm 

(4 weeks)

11 (8 weeks – 

1,344 hours)

34.6 65.3 95.9 32 0.57 at 492 fpm 

(8 weeks)

10 (16 weeks – 

2,688 hours)

27.5 53.7 89.8 50 0.58 at 492 fpm 

(16 weeks)

 C14PCS Pleated 

microfiberglass 

(commercial)

No 14B 12 (0 weeks – 0 

hours)

71.3 89.4 98.6 0 0.60 at 500 

fpm

0.60 at 492 fpm 

(0 weeks)

Collection 

efficiency 

was very 

consistent 

during entire 

test period.

14 (2 weeks – 

336 hours)

79.0 92.5 99.4 17 0.62 at 492 fpm 

(2 weeks)

13 (4 weeks – 

672 hours)

73.2 90.3 98.6 26 0.62 at 492 fpm 

(4 weeks)

14 (8 weeks – 

1,344 hours)

78.1 91.9 98.7 39 0.64 at 492 fpm 

(8 weeks)

14 (16 weeks – 

2,688 hours)

83.8 97.3 99.3 76 0.66 at 492 fpm 

(16 weeks)
42

Table 4–5. Summary of the Results from the Filter Aging Evaluations (Continued)

Filter Description Electrostatic

MERV 

Rating 

(literature)

MERV Rating 

from testing 

(Hours of HVAC 

Operation)

Average Collection Efficiencies 

(%) Approximate 

Mass of Dust 

Collected 

(grams)

Literature 

Pressure Drop

(in. w.g.)

Measured 

Pressure Drop 

(in. w.g.) Notes

E1 

0.3–1.0 

μm

E2 

1.0–3.0 

μm

E3

3.0–10 

μm

C11GM-1 95% DOP 

Pleated 

microfiberglass 

(commercial)

No 16 16 (0 weeks – 0 

hours)

98.6 99.9 100 0 0.61 at 500 

fpm

0.85 at 492 fpm 

(0 weeks)

Collection 

efficiency 

was very 

consistent 

during entire 

test period.

16 (2 weeks – 

336 hours)

98.5 99.9 100 11 0.84 at 492 fpm 

(2 weeks)

16 (4 weeks – 

672 hours)

98.7 99.9 100 22 0.83 at 492 fpm 

(4 weeks)

16 (8 weeks – 

1,344 hours)

98.7 99.9 99.9 42 0.83 at 492 fpm 

(8 weeks)

16 (16 weeks – 

2,688 hours)

99.2 100 100 81 0.86 at 492 fpm 

(16 weeks)

B – MERV rating based on Table E-1 in ASHRAE 52.2-1999
43

Figure 4-31. Measured Collection Efficiency of Residential Filter 6DDUE-8 During the Aging 

Evaluations

Figure 4-32. Measured Pressure Drop of Residential Filter 6DDUE-8 During the Aging 

Evaluations
44

Figure 4-33. Measured Collection Efficiency of Residential Filter 8NM-10 During the Aging 

Evaluations

Figure 4-34. Measured Pressure Drop of Residential Filter 8NM-10 During the Aging 

Evaluations
45

Figure 4-35. Measured Collection Efficiency of Commercial Filter C17FPP-8 During the Aging 

Evaluations

Figure 4-36. Measured Pressure Drop of Commercial Filter C17FPP-8 During the Aging 

Evaluations
46

Figure 4-37. Measured Collection Efficiency of Commercial Filter C15AAA-11 During the Aging 

Evaluations

Figure 4-38. Measured Pressure Drop of Commercial Filter C15AAA-11 During the Aging 

Evaluations
47

Figure 4-39. Measured Collection Efficiency of Commercial Filter C8GZ-13 During the 

Aging Evaluations

Figure 4-40. Measured Pressure Drop of Commercial Filter C8GZ-13 During the Aging 

Evaluations
48

Figure 4-41. Measured Collection Efficiency of Commercial Filter C14PCS During the Aging 

Evaluations

Figure 4-42. Measured Pressure Drop of Commercial Filter C14PCS During the Aging 

Evaluations
49

Figure 4-43. Measured Collection Efficiency of Commercial Filter C11GM-16 During the Aging 

Evaluations

Figure 4-44. Measured Pressure Drop of Commercial Filter C11GM-16 During the Aging 

Evaluations
50

4.3.2 Aging Evaluations – Electronic Air Cleaners

Table 4-6 summarizes the results from the EAC aging 

evaluations. Figures 4-45 through 4-50 provide graphic 

illustrations of the test results. In contrast to the filter aging, a 

single EAC was evaluated over the aging period, eliminating 

the contribution of unit variation into the measured pressure 

drops and collection efficiencies. It should be noted that no 

cleaning was performed over the entire aging duration. This 

was consistent with the manufacturer’s recommendations of 

cleaning intervals between 1 and 6 months in duration. (In 

general, according to the manufacturer’s literature, cleaning 

was recommended only when a visible inspection indicated 

that cleaning was clearly required.)

The pressure drops of all three units remained consistent over 

the entire aging period, demonstrating neither significant 

changes nor any discernable pattern. Unit A appeared to 

demonstrate a small drop in collection efficiency between 

336 hours and 1,008 hours of use, as it dropped from a 

MERV 15 to a MERV 14, but it should be noted that this was 

due to a minor decrease in the average efficiency for 0.3 to 

1 μm particles (from 87.6% to 83.2%), as the efficiencies 

in the other particle size ranges were virtually identical. 

The average efficiency for 0.3 to 1 μm particles for Unit 

A decreased slightly again between 1,008 and 2,016 hours 

(from 83.2% to 80.7%), but again the efficiencies in the other 

particle size ranges were virtually identical. By far, Unit A 

demonstrated the least degradation in performance over the 

aging period and appeared to be operating satisfactorily even 

after 2,016 hours of use without any maintenance.

Unit H also performed reasonably well over the aging period 

but showed more degradation than Unit A between 336 

and 1,008 hours of aging, even though its MERV rating did 

not change. Its average efficiency for 0.3 to 1 μm particles 

decreased from 93.4% to 86.8% between 336 and 1,008 

hours of operation. As shown in Figure 4-47, the MERV 

rating for Unit H decreased to 12 after 2,016 hours of 

operation, corresponding to a decrease in average efficiency 

for 0.3 to 1 μm particles from 86.8% to 74.7%, as well 

as decreases for larger particles. Cleaning of Unit H after 

84 days of continuous operation appeared to be warranted.

In contrast, Unit P decreased slightly in collection efficiency 

for particles smaller than 1 μm between 168 and 336 hours 

of use, and then dropped precipitously from a MERV 14 

to a MERV 6 between 336 hours and 1,008 hours of use. 

Despite the significant drop in collection efficiency for Unit P 

between 336 hours and 1,008 hours, the visible buildup on 

the unit was not substantial enough to warrant cleaning. 

Unit P was not visibly dirtier than the other two units, so 

the user would have no reason to suspect that performance 

had substantially degraded. However, based on its collection 

efficiency, cleaning of Unit P would be recommended after 

14 days of continuous use.
51

Table 4-6. Summary of the Results from the Electronic Air Cleaner Aging Evaluations

Unit MERV Rating (literature) MERV Rating (testing)

Average Collection Efficiencies (%)

Literature Pressure Drop 

(in. w.g.)

Measured Pressure 

Drop (in. w.g.) Notes

E1

0.3-1.0 μm

E2

1.0-3.0 μm

E3

3.0-10 μm

A > 94% at 0.35 μm (MERV 15) 14 (aged 0 hours) 84.2 93.1 97.9 0.17 at 500 fpm 0.12 at 295 fpm None

15 (aged 168 hours) 88.3 94.5 97.3 0.16 at 295 fpm15 (aged 336 hours) 87.6 94.8 98.2 0.12 at 295 fpm

14 (aged 1,008 hours) 83.2 93.6 96.8 0.16 at 295 fpm14 (aged 2,016 hours) 80.7 93.8 96.8 0.15 at 295 fpm

H Up to MERV 12 at 492 fpm 15 (aged 0 hours) 92.7 96.9 98.1 0.06 at 295 fpm 0.11 at 295 fpm None

15 (aged 168 hours) 92.6 97.3 98.3 0.09 at 295 fpm15 (aged 336 hours) 93.4 97.2 98.2 0.13 at 295 fpm

15 (aged 1,008 hours) 86.8 95.6 98.1 0.13 at 295 fpm12 (aged 2,016 hours) 74.7 89.4 94.6 0.13 at 295 fpm

P NA 14 (aged 0 hours) 84.0 95.1 97.1 0.11 at 500 fpm 0.06 at 295 fpm None

14 (aged 168 hours) 82.3 94.7 97.6 0.05 at 295 fpm14 (aged 336 hours) 78.5 93.2 96.8 0.05 at 295 fpm

6 (aged 1,008 hours) 18.4 27.7 46.8 0.07 at 295 fpm5 (aged 2,016 hours) 4.1 5.6 21.8 0.06 at 295 fpm
52

Figure 4-45. Measured Collection Efficiency of Electronic Air Cleaner A During the Aging 

Evaluations

Figure 4-46. Measured Pressure Drop of Electronic Air Cleaner A During the Aging Evaluations
53

Figure 4-47. Measured Collection Efficiency of Electronic Air Cleaner H During the Aging 

Evaluations

Figure 4-48. Measured Pressure Drop of Electronic Air Cleaner H During the Aging Evaluations
54

Figure 4-49. Measured Collection Efficiency of Electronic Air Cleaner P During the Aging 

Evaluations

Figure 4-50. Measured Pressure Drop of Electronic Air Cleaner P During the Aging Evaluations
55

4.4 Results from the Conditioning Evaluations

As described in Section 3.4, eight electrostatic filters 

were evaluated using a modified inert aerosol test method 

(Section 3.1) that involved conditioning to identify their 

minimum collection efficiency, rather than their initial 

collection efficiency. This modified inert aerosol test method 

was performed in accordance with the latest recommendation 

from ASHRAE, namely draft Addendum C for ANSI/

ASHRAE Standard 52.2-1999.

Similarly, as described in Section 3.5, three EACs were 

evaluated by the inert aerosol methods described in Section 

3.1 both before and after exposure to silicon vapor. The 

purpose of the exposure to silicon vapor was to compare the 

results from exposure to silicon vapor to the results from 

the “in-use” tests to determine whether the silicon vapor 

exposure resulted in a realistic assessment of the EACs’ 

likely performance after one month of actual use.

All of the inert aerosol tests of the conditioned units were 

performed at the same airflow rate, which was the maximum 

flow rate the units would likely encounter in actual use. The 

pressure drops of the devices were also evaluated at the 

test flow rate. A complete listing of the results from these 

evaluations for each air cleaner is provided in Appendix H. A 

summary of the results is provided for the filters and EACs in 

the following sections.

4.4.1 Results from the Conditioning Evaluations – 

Filters

As discussed in Section 3.4, eight electrostatic filters were 

evaluated before, during, and after a series of conditioning 

steps. The conditioning was performed according to draft 

Addendum C for ASHRAE 52.2-1999, which is aimed 

at developing a repeatable test method for evaluating 

the performance of electrostatic filters in actual use. 

(Electrostatic filters are generally known to decrease in 

collection efficiency when initially loaded and to continue 

this decrease until the dust cake that builds up is sufficient 

to counteract the decrease in the efficiency of electrostatic 

attraction as the available surface area on the filter fibers 

decreases.) As discussed in Section 3.4, the test method 

consisted of multiple collection efficiency evaluations 

between loadings with submicron potassium chloride 

particles. A summary of the results is provided in Table 

4-7. Illustrations of the results are provided in Figures 4-51 

through 4-63. For the convenience of the reader, charts of 

selected results from the aging evaluations are included in 

Figures 4-51 through 4-63 to allow a direct comparison.

As shown in Figure 4-51, for residential filter 6DDUE‐8, 

upon conditioning, the collection efficiency increased 

significantly for particles larger than 1 μm but appeared 

to decrease slightly for particles smaller than 1 μm. 

This was consistent with the observations during the 

aging tests shown in Figure 4-52, in which the collection 

efficiency increased upon aging for particles larger than 

4 μm but decreased significantly for particles smaller 

than 2 μm, until approximately 12 weeks of aging had 

occurred. Residential filters 5RM-11-1, 4FUA-12-3, 

and 7AST-8-3, for which there are no aging test results 

to compare, behaved similarly to filter 6DDUE-8. As 

shown in Figures 4-53, 4-54, and 4-55, upon conditioning, 

the collection efficiency of all three residential filters 

increased for particles larger than approximately 1 to 

2 μm but either decreased slightly or remained essentially 

constant during the entire conditioning process.

As shown in Figure 4-56, for residential filter 8NM-10, the 

collection efficiency decreased slightly for all particles upon 

initial conditioning but increased for all particles once the 

equivalent of one month of conditioning had been performed. 

This is similar to the results observed during the aging tests 

shown in Figure 4-57, although the decrease was more 

substantial and required approximately 12 weeks of aging to 

increase past the initial values.
56

Table 4-7. Summary of the Results from the Filter Conditioning Evaluations

Filter Description

MERV 

Rating 

(literature)

MERV Rating 

from testing 

(CTa)

Average Collection Efficiencies (%) Approximate 

Months of Use 

Simulated

Literature 

Pressure Drop 

(in. w.g.)

Measured 

Pressure Drop 

(in. w.g.) Notes

E1

0.3-1.0 μm

E2

1.0-3.0 μm

E3

3.0-10 μm

6DDUE-8-

11

Pleated 

electrostatic 

(residential)

8 7 (0) 20.6 51.9 56.8 0 0.17 at 295 fpm 0.14 at 295 fpm None

11 (3.2 * 107) 17.4 69.9 88.8 0.3 0.14 at 295 fpm11 (6.9 * 107) 15.6 69.2 87.3 0.7 0.14 at 295 fpm11 (1.0 * 108) 20.9 75.4 92.4 1 0.21 at 295 fpm

8NM-10-11 Pleated 

electrostatic 

(residential)

10 12 (0) 31.2 82.4 91.4 0 NA 0.43 at 295 fpm None

11 (5.0 * 107) 24.7 79.0 85.8 0.5 0.42 at 295 fpm11 (7.5 * 107) 31.5 81.9 86.9 0.7 0.46 at 295 fpm12 (1.1 * 108) 46.1 89.3 94.2 1.1 0.63 at 295 fpm

C17FPP-8 Pleated 

electrostatic 

prefilter 

(commercial)

8 7 (0) – 12 x 24 x 2 39.1 75.5 64.7 0 0.30 at 500 fpm 0.55 at 492 fpm 

(0 weeks)

None

8 (0) 48.3 91.1 81.3 0 0.44 at 492 fpm

13 (3.2 * 107) 51.7 94.6 98.2 0.3 0.47 at 492 fpm13 (6.6 * 107) 51.7 94.6 98.0 0.7 0.47 at 492 fpm

C15AAA-11 Pleated 

electrostatic 

prefilter 

(commercial)

11 8 (0) – 12" x 24" 

x 2"

47.5 72.9 71.4 0 0.38 at 500 fpm 0.40 at 492 fpm 

( 0 weeks)

Collection 

efficiency 

was well 

below 

expected 

values.

7 (0) 41.1 71.9 66.6 0 0.34 at 492 fpm

11 (3.2 * 107) 29.5 76.2 88.6 0.3 0.33 at 492 fpm

8 (8.0 * 107) 24.6 70.8 79.8 0.8 0.29 at 492 fpm

11 (1.1 * 108) 25.7 73.3 85.0 1.1 0.46 at 492 fpm

C8GZ-13 Pleated 

synthetic 

box filter 

(commercial)

13 14 (0) 77.5 96.3 98.7 0 0.44 at 500 fpm 0.63 at 492 fpm NA

13 (3.2 * 107) 73.7 96.7 98.6 0.3 0.64 at 492 fpm14 (6.4 * 107) 75.6 96.9 98.1 0.6 0.65 at 492 fpm13 (9.6 * 107) 73.4 96.7 98.8 1 0.67 at 492 

fpm

5RM-11-1 Pleated 

electrostatic 

(residential)

11 7 (0) 19.2 64.9 68.7 0 0.12 at 250 fpm 0.25 at 295 fpm NA

11 (3.4 * 107) 15.8 68.8 86.8 0.3 NA11 (6.6 * 107) 19.1 75.1 94.1 0.6 NA

aCT = concentration*time, in units of (particles*min)/cm3.
57

Table 4-7. Summary of the Results from the Filter Conditioning Evaluations (Continued)

Filter Description

MERV 

Rating 

(literature)

MERV Rating 

from testing 

(CTa)

Average Collection Efficiencies (%) Approximate 

Months of Use 

Simulated

Literature 

Pressure Drop 

(in. w.g.)

Measured 

Pressure Drop 

(in. w.g.) Notes

E1

0.3-1.0 μm

E2

1.0-3.0 μm

E3

3.0-10 μm

4FUA-12-3 Pleated 

electrostatic 

(residential)

12 12 (0) 39.7 80.8 92.1 0 NA 0.09 at 295 fpm NA

12 (3.3 * 107) 32.6 80.2 96.4 0.3 NA11 (6.8 * 107) 31.0 78.7 96.6 0.7 NA12 (1.1 * 108) 33.7 81.2 97.4 1.1 NA

7AST-8-3 Pleated 

electrostatic 

(residential)

8 7 (0) 19.0 62.6 61.3 0 NA 0.09 at 295 fpm NA

11 (3.2 * 107) 17.2 72.0 86.6 0.3 NA11 (6.9 * 107) 21.7 77.8 89.8 0.7 NA12 (1.0 * 108) 32.7 87.6 96.7 1.0 NA

aCT = concentration*time, in units of (particles*min)/cm3.
58

Figure 4-51. Measured Collection Efficiency of Filter 6DDUE-8-11 During the Conditioning 

Evaluations

Figure 4-52. Measured Collection Efficiency of Residential Filter 6DDUE-8 During the Aging 

Evaluations
59

Figure 4-53. Measured Collection Efficiency of Filter 5RM-11-1 During the Conditioning 

Evaluations

Figure 4-54. Measured Collection Efficiency of Filter 4FUA-12-3 During the Conditioning 

Evaluations
60

Figure 4-55. Measured Collection Efficiency of Filter 7AST-8-3 During the Conditioning Evaluations

Figure 4-56. Measured Collection Efficiency of Filter 8NM-10-11 During the Conditioning 

Evaluations
61

Figure 4-57. Measured Collection Efficiency of Residential Filter 8NM-10 During the Aging 

Evaluations

Figure 4-58. Measured Collection Efficiency of Filter C15AAA-11 During the Conditioning 

Evaluations
62

Figure 4-59. Measured Collection Efficiency of Commercial Filter C15AAA-11 During the Aging 

Evaluations

Figure 4-60. Measured Collection Efficiency of Filter C17FPP-8 During the Conditioning 

Evaluations
63

Figure 4-61. Measured Collection Efficiency of Commercial Filter C17FPP-8 During the Aging 

Evaluations

Figure 4-62. Measured Collection Efficiency of Filter C8GZ-13 During the Conditioning 

Evaluations
64

Figure 4-63. Measured Collection Efficiency of Commercial Filter C8GZ-13 During the Aging 

Evaluations

Similar to the residential filters, the aging and conditioning 

tests of commercial prefilter C15AAA-11 appeared to be 

consistent. As shown in Figure 4-58, the conditioning of 

commercial prefilter C15AAA-11 resulted in a noticeable 

decrease in collection efficiency for all particles less 

than approximately 1 μm, with no recovery during the 

approximately one month equivalent of conditioning. The 

aging of prefilter C15AAA-11 also resulted in a decrease 

(although more substantial) in collection efficiency for all 

particles smaller than approximately 4 μm, with no recovery 

over 16 weeks of aging, as depicted in Figure 4-59. 

In contrast, the aging and conditioning tests of the remaining 

two commercial filters (C17FPP-8 and C8GZ-13) did 

not produce consistent results. For commercial prefilter 

C17FPP-8, the collection efficiency increased slightly for 

all particles upon initial conditioning and remained at the 

same level with further conditioning (Figure 4-60). This 

result noticeably contrasted with the results from the aging 

evaluations (Figure 4-61), in which the collection efficiency 

decreased substantially for particles smaller than 4 μm 

with aging and did not increase over 16 weeks of use. For 

commercial box filter C8GZ-13, the results from the aging 

and conditioning evaluations contrasted even more strongly. 

In the conditioning evaluation shown in Figure 4-62, the 

collection efficiency of filter C8GZ-13 remained essentially 

constant during the approximately one month equivalent of 

conditioning, even increasing slightly for particles smaller 

than 0.3 μm. However, during the 16 weeks of aging, filter 

C8GZ-13 consistently and continually decreased in collection 

efficiency for all particles during the entire period, as shown 

in Figure 4-63.

It is not known why the trends in the results from the 

conditioning evaluations are consistent with the aging 

results for three of the filters but inconsistent with the aging 

results for the other two filters. Further investigation of these 

contrasting results seems warranted but is beyond the scope 

of the present effort. It should again be noted that during the 

conditioning evaluations, a single filter was used. In contrast, 

the aging evaluations were performed with five different 

filters of identical make, model, and size. Therefore, some 

variability is present in the aging evaluations due to the 

different performance levels of the individual filters, as well 

as between the filters used in the conditioning evaluation and 

the aging evaluations.

4.4.2 Results from the Conditioning Evaluations – 

Electronic Air Cleaners

As described in Section 3.5, three EACs were evaluated 

by the inert aerosol methods described in Section 3.1 both 

before and after exposure to silicon vapor. The purpose of 

the exposure to silicon vapor was to compare the results from 

exposure to silicon vapor to the results from the “in-use” tests 

to determine whether the silicon vapor exposure resulted in 

a realistic assessment of their likely performance after one 

month of actual use.

A summary of the results is provided in Table 4-8. Individual 

results, along with a comparison to the results from the 

aging tests of the EACs are provided in Figures 4-64, 4-65, 

and 4-66. As shown in Figures 4-64 and 4-66, the silicon 

vapor exposure of Units A and P appeared to cause a very 

similar degradation to that likely to be observed after one 

month of ambient aging (672 hours of use). In both Figures 
65

4-64 and 4-66, the collection efficiency of the electronic air 

cleaner degraded more than that observed during 336 hours 

(2 weeks) of ambient use but less than that observed after 

1,008 hours (6 weeks) of ambient use. For Unit H, however, 

the silicon vapor exposure degraded the unit’s performance 

well beyond that observed after even 2,016 hours of ambient 

aging (12 weeks of continuous operation).

It is not known why the results from the aging and 

conditioning evaluations are consistent for units A and P but 

inconsistent for Unit H. It could be a result of a large number 

of design and component differences between the three units. 

Given the approximately 50% decrease in pressure drop in 

Unit H after silicon vapor exposure, and the alteration in the 

shape of the collection efficiency curve, it is possible that the 

exposure allowed leakage to occur within the unit. Further 

investigation of the contrasting results for Unit H seems 

warranted but is beyond the scope of the present effort.

It should be noted that in contrast to the filter evaluations, 

during the EAC aging evaluations, a single unit was used. 

Therefore, no variability was present within the EAC aging 

evaluations due to the different performance levels of 

individual units. In addition, the initial collection efficiency 

tests (shown in Table 4-3 and Figure 4-19) indicated that 

the variability between the EACs used in the conditioning 

evaluation versus those used in the aging evaluations was 

very small.

Table 4-8. Summary of the Results from the Silicon Vapor Exposures of the Electronic Air Cleaners

Unit

MERV 

Rating 

from 

Vendor

MERV Rating 

from Testing 

(Exposure 

Status)

Average Collection Efficiencies (%)

Literature 

Pressure Drop 

(in. w.g.)

Measured 

Pressure Drop 

(in. w.g.) Notes

E1

0.3–1.0 

μm

E2

1.0–3.0 

μm

E3

3.0–10 

μm

A 15

15 (before) 90.8 94.4 96.6

0.17 @ 504 fpm

0.11 @ 295 fpm Very 

consistent 

with aging 

15 (after) 86.6 93.9 98.1 0.13 @ 295 fpm tests

H Up to 12

15 (before) 91.5 97.2 98.8

0.06 at 295 fpm

0.11 @ 295 fpm Not 

consistent 

with aging 

tests 6 (after) 52.3 53.8 47.1 0.05 @ 295 fpm

P NA

14 (before) 82.5 95.3 96.9

0.11 at 504 fpm

0.08 @ 295 fpm Very 

consistent 

with aging 

tests 7 (after) 33.3 43.6 50.5 0.06 @ 295 fpm
66

Figure 4-64. Measured Collection Efficiencies for Electronic Air Cleaner A Before and After Exposure to 

Silicon Vapor

Figure 4-65. Measured Collection Efficiencies for Electronic Air Cleaner H Before and After Exposure to 

Silicon Vapor
67

Figure 4-66. Measured Collection Efficiencies for Electronic Air Cleaner P Before and After 

Exposure to Silicon Vapor

4.5 Quality Assurance

Work under this task was completed in accordance with a 

pair of EPA-approved quality assurance test plans (QAPPs) 

entitled “Research on Air Cleaning and HVAC Systems for 

Protecting Buildings from Terrorist Attacks; Test/Quality 

Assurance Plan for Task 2: Development of Performance 

Information for Common Ventilation Filters” (Battelle, 

2005a), and “Research on Air Cleaning and HVAC Systems 

for Protecting Buildings from Terrorist Attacks; Test/Quality 

Assurance Plan for Task 3: Development of Performance 

Information for Electronic Air Cleaners” (Battelle, 2005b). 

The text from these two QAPPs was included in the relevant 

portions of this report, for example, the development of the 

filter and electronic air cleaner tests matrices (Section 2), the 

inert aerosol and bioaerosol test procedures (Sections 3.1.1 

and 3.2.1), and the data analysis procedures (Sections 3.1.2 

and 3.2.2).

In accordance with the QAPPs (Battelle 2005a; Battelle, 

2005b), an external quality assurance (QA) audit of Tasks 

2/3 was performed by an EPA staff member and a designated 

representative on 9 August 2006 at Battelle’s Columbus 

facility. The quality assurance inspectors reviewed the 

sample handling logs, standard operating procedures, test 

record sheets, instrument calibration sheets, data logs and 

data sheets from the inert and bioaerosol tests, and various 

other documentation. In addition, the quality assurance 

inspectors witnessed the performance of a bioaerosol test. 

Official documentation from the QA inspectors was received 

on 8 September 2006. No corrective actions were deemed 

necessary. Additional information on the quality assurance 

procedures and results can be found in Appendix I.
68

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69

5.0

Curve Fitting to the “Off-the-Shelf ”

Air Cleaner Results

As clearly evidenced by this study, a variety of options exist 

for the removal of particles in residential and commercial 

HVAC systems. There are a number of selection criteria to 

be considered when choosing an air cleaner for a specific 

HVAC system, including (but not limited to) cost, pressure 

drop, service life, maintenance requirements, collection 

efficiency, power requirements, and required/desired clean 

air specifications. In order to choose the optimal air cleaner 

for a specific HVAC system, all of these factors need to be 

considered and, in some cases, modeled. Therefore, empirical 

equations were developed based on the data acquired during 

this effort relating particle collection efficiency to particle 

physical diameter over the range of 0.03 to 10 μm. These 

equations can be incorporated into indoor air quality models. 

The results from these modeling efforts are provided below.

5.1 Curve Fits to the Inert Aerosol Filter Evaluations

Empirical equations were developed based on the data 

acquired during the evaluations of the “off-the-shelf ” 

filters relating particle collection efficiency to particle 

physical diameter over the range of 0.03 to 10 μm. These 

equations were developed only for unaged, unconditioned 

filters, and one curve was fit to all of the filters whose test 

results resulted in a given MERV rating. The curves were 

fit using TableCurve 2D software (SYSTAT Software Inc.). 

To generate the curves, all of the experimental collection 

efficiency results for a given MERV rating were combined 

into one spreadsheet. When more than one set of data was 

used, the data were combined by averaging the penetrations 

and weighting the mean values proportionally to the inverse 

of the standard deviation of the values. At the direction of the 

sponsor, a 3rd order polynomial was fit between the log of 

the penetration and the log of the particle diameter. To avoid 

difficulties with taking logarithmic values of penetrations 

of 0%, the curves for the MERV 16 and HEPA filters had to 

be fit to the natural logarithm and the numerical penetration, 

respectively, versus the log of the particle diameter. The 

results from the curve fits are summarized in Table 5-1 and 

illustrated in Figures 5-1 through 5-9. As shown in Table 

5-1 and the various figures, all but one of the curve fits 

possessed correlation coefficients (r squared) greater than 

0.89, indicating an excellent representation of the data. The 

MERV 6 curve fit possessed a lower correlation value (0.83), 

but as shown in Figure 5-2, the fitted curve matched the data 

well. In all cases, it is not recommended that the curve fits be 

extrapolated outside of the particle size range used to develop 

them (0.03 to 10 μm). It should be noted that the curve fits 

will provide an empirically validated prediction for the 

performance of a filter that performs at a given MERV rating, 

not a prediction for a particular make and model of filter.
70

Table 5-1. Summary of the Results from the Curve Fits to the Inert Aerosol Evaluations of Unaged Unconditioned Air Filters

MERV Rating Equation Parameters Correlation Coefficient (r2)

5 Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 1.8906

b = -0.1722

c = 0.0307

d = 0.0793

0.8935

6 Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 1.9311

b = -0.1441

c = -0.1243

d = -0.0234

0.8332

7 Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 1.7467

b = -0.3314

c = -0.0036

d = 0.1381

0.9064

8 (1/Y) = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 0.5839

b = 0.1675

c = 0.1289

d = 0.0188

0.9658

10 Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 1.7083

b = -0.5759

c = -0.6721

d = -0.1775

0.9852

12 Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 1.3943

b = -0.9080

c = -0.6240

d = -0.0404

0.9902

14 Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 0.9531

b = -1.4941

c = -0.8443

d = -0.0013

0.9668

16 Ln Y = a + bx + cx2 + dx3

where Y = percent penetration

x = log of particle diameter

a = 0.3855

b = -2.0698

c = 0.5326

d = 1.3895

0.9728

16+ (HEPA) Y = a + bx + cx2 + dx3 + ex4

where Y = percent penetration

x = log of particle diameter

a = 0.0361

b = -0.3506

c = 0.5119

d = 0.0481

e = -0.1816

0.8917
71

Figure 5-1. Curve Fit to the Empirical Data for the Single Unaged, Unconditioned MERV 5 

Filter

Figure 5-2. Curve Fit to the Empirical Data for the Two Unaged, Unconditioned MERV 6 Filters
72

Figure 5-3. Curve Fit to the Empirical Data for the Six Unaged, Unconditioned MERV 7 Filters

Figure 5-4. Curve Fit to the Empirical Data for the Four Unaged, Unconditioned MERV 8 Filters
73

Figure 5-5. Curve Fit to the Empirical Data for the Single Unaged, Unconditioned MERV 10 Filter

Figure 5-6. Curve Fit to the Empirical Data for the Five Unaged, Unconditioned MERV 12 Filters
74

Figure 5-7. Curve Fit to the Empirical Data for the Four Unaged, Unconditioned MERV 14 Filters

Figure 5-8. Curve Fit to the Empirical Data for the Three Unaged, Unconditioned MERV 16 Filters
75

Figure 5-9. Curve Fit to the Empirical Data for the Single Unaged, Unconditioned MERV 16+ 

(HEPA) Filter

5.2 Curve Fits to the Inert Aerosol Electronic Air 

Cleaner Evaluations 

In contrast to the curve fitting of the filter results, a single 

curve was fit to all of the “off-the-shelf ” electronic air 

cleaner results. The results are illustrated in Table 5-2 and 

Figure 5-10. As shown in Table 5-2 and Figure 5-10, an 

excellent correlation between the collected data and the curve 

fit was obtained, as the EACs all had very similar MERV 

ratings (either 14 or 15) and similar collection efficiency 

curves.

Table 5-2. Summary of the Results from the Curve Fits to the Inert Aerosol Evaluations of Unaged Unconditioned 

Electronic Air Cleaners

MERV Rating Equation Parameters Correlation Coefficient (r2)

14 and 15 (all unaged 

unconditioned EACs)

Y = a + bx + cx2 + dx3

where Y = log of percent penetration

x = log of particle diameter

a = 0.8422

b = -0.6469

c = -0.2157

d = 0.1645

0.9600
76

0

10

20

30

40

50

60

70

80

90

100

0.01 0.1 1 10

Particle Size (microns)

Removal Efficiency (%)

Unit P - Used for aging

Unit P - Used for silicon vapor exposure

Unit H - Used for aging

Unit H - Used for silicon vapor exposure

Unit A - Used for aging

Unit A - Used for silicon vapor exposure

Curve Fit Results

Figure 5-10. Curve Fit to the Empirical Data for the Six Unaged, Unconditioned Electronic Air 

Cleaners
77

6.0

Conclusions and Recommendations

As described in the initial sections of this report, four distinct 

types of testing were performed under this effort. First, a 

total of 27 commonly used air cleaning devices (24 filters 

and 3 EACs) were acquired and evaluated for their pressure 

drop and collection efficiency, as received (“off-the-shelf ”). 

Empirical equations were developed for the data collected 

during these tests relating particle collection efficiency to 

particle physical diameter over the range of 0.03 to 10 μm. 

Second, ten devices (seven filters and three EACs) were 

evaluated for their bioaerosol collection efficiency. Third, 

a different subset of ten devices (seven filters and three 

EACs) were evaluated for their pressure drop and collection 

efficiency after approximately 1 or 2 weeks, 2 or 4 weeks, 6 

or 8 weeks, and 12 or 16 weeks of normal use. Fourth, eight 

filters and three EACs were “conditioned” via methodologies 

anticipated to simulate an actual use environment. Eight 

electrostatic filters were conditioned by loading with a 

submicrometer inert aerosol, while the three EACs were 

evaluated both before and after exposure to silicon vapor. 

Summaries of the results and conclusions from each of these 

efforts are provided below. 

6.1 Results from Inert Aerosol Evaluations of

“Off-the-Shelf ” Filters

The measured pressure drops of the “off-the-shelf ” filters 

generally corresponded quite well (± 30%) with the 

information provided by the vendors, although, in a few 

cases, the measured pressure drops were somewhat greater. 

With the exception of several MERV 11 filters, the MERV 

ratings that were determined from the tests were generally 

equivalent or within one or two MERV ratings of the 

manufacturer data. The testing during this study consisted 

of evaluating single filters; therefore, the results may not be 

representative of typical performance. 

Except for the MERV 8 filters, the collection efficiency 

curves obtained for the filters with identical MERV ratings 

were similar in shape. Two of the MERV 8 filters possessed 

curves with shapes similar to those of lower MERV ratings 

(MERV 5 through 7), and two of the MERV 8 filters 

possessed curves similar to those with greater MERV 

ratings (MERV 9 through 16). For all of the MERV ratings, 

collection efficiencies measured with the Climet model 500 

Spectrometer (OPC) (0.3 to 10 μm) generally corresponded 

very well to the collection efficiencies measured with the 

TSI SMPS (0.03 to 0.3 μm). The most penetrating particle 

size was consistently in the 0.1 to 0.3 μm range, which is 

consistent with typical filtration efficiency curves.

Table 6-1 provides a summary of the results from the inert 

aerosol evaluations of unconditioned, unaged (“off-theshelf ”) filters. As shown in Table 6-1, the pressure drops of 

the filters between MERV 5 and 10 at 370 fpm did not appear 

to be substantially different, with a good deal of overlap 

between the average pressure drops. However, there was a 

significant increase in pressure drops between the MERV 10 

and MERV 12 filters, between the MERV 14 and MERV 16 

filters, and between the MERV 16 filters and the HEPA filter. 

As expected, the collection efficiency of the filters generally 

increased with MERV rating. Therefore, consumers of air 

filters will need to balance the higher pressure drops and 

costs of MERV 12 to MERV 16 filters with the expected 

increase in performance. (MERV 12 was the highest MERV 

rating found for a residential filter.)

In contrast to procurement of the residential filters, during 

procurement of the commercial filters, difficulties in 

obtaining serviceable filters of the correct model and size 

were experienced with nearly one-third of the procured test 

filters. These difficulties included shipment of incorrect (but 

similar) models, incorrect sizes, incorrect frame types and 

materials, and damaged or improperly constructed filters. For 

consumers concerned with filter performance, care must be 

taken to inspect filters before use to ensure that the filters are 

appropriate for use.

As described in Section 5 and Table 5-1, curves were fit to 

the collection efficiencies that were measured for the “offthe-shelf ” filters. All but one of the curve fits possessed 

correlation coefficients (r squared) greater than 0.89, 

indicating an excellent representation of the data. The MERV 

6 curve fit possessed a lower correlation value (0.83) but 

matched the data well. In all cases, it is not recommended 

that the curve fits be extrapolated outside of the particle size 

range used to develop the curve fits (0.03 to 10 μm). These 

curve fits provide a valuable tool that will enable consumers 

to accurately estimate the collection efficiency of a filter 

with a given MERV rating to determine whether its likely 

performance will justify its increased cost and pressure drop.
78

Table 6-1. Summary of the Results from the Inert Aerosol Evaluations and Curve Fits of Unaged

Unconditioned Air Filters

MERV 

Rating

Number 

of Filters 

Tested

Average Pressure Drop 

(in. of water)

at 370 fpm

Predicted Collection Efficiencies from Curve Fits (%)

0.03 μm 0.1 μm 0.3 μm 1.1 μm 3.5 μm 8.4 μm

5 1 0.24 13 0 5 24 34 34

6 2 0.22 ± 0.06 12 6 5 16 35 53

7 6 0.30 ± 0.08 44 13 20 47 61 65

8 4 0.26 ± 0.03 40 20 22 52 75 86

10 1 0.29 55 37 29 53 85 97

12 5 0.46a ± 0.09 71 47 49 78 95 99

14 4 0.48b ± 0.11 82 59 68 93 99 99

16 3 0.73 ± 0.15 99 95 96 99 99 99

16+ (HEPA) 1 0.97 >99 >99 >99 >99 >99 >99

a

 – neglecting electrostatic filter 4FUA-12-3, which had a pressure drop of only 0.13 inches of water

b

 – neglecting filter C6-ADP-15-1, which was evaluated well above its nominal flow rate

6.2 Results from Inert Aerosol Evaluations of “Offthe-Shelf ” Electronic Air Cleaners

The measured pressure drops of two of the three tested units 

(A and P) corresponded well with the information provided 

by the manufacturers, while the pressure drop for Unit H was 

nearly double the expected value. However, the measured 

pressure drops for the EACs averaged 0.14 + 0.03 inches of 

water at 370 feet per minute, which is approximately one-half 

that of the average pressure drop for MERV 5 to 10 filters. 

In terms of collection efficiency, the MERV ratings that were 

determined from the tests ranged from one MERV rating 

below to three MERV ratings above the manufacturer data. 

The MERV ratings were also consistent with the two samples 

of each unit that were evaluated. As with the filter testing, 

the testing during this study consisted of evaluations of pairs 

of the units; therefore, the results may not be representative 

of typical performance. (ANSI/ASHRAE 52.2-1999 does 

not provide any guidance regarding the number of samples 

of an EAC that should be tested to provide a statistically 

reasonable representation of their typical performance.)

As with the filters, the collection efficiency curves obtained 

for the EACs were quite similar in shape. In addition, 

collection efficiencies measured with the OPC (0.3 to 10 

μm) generally corresponded very well with the collection 

efficiencies measured with the SMPS (0.03 to 0.3 μm). Given 

that the EACs possessed MERV ratings of 14 and 15, at least 

initially, they appeared to offer considerably higher collection 

efficiencies than air filters for a given pressure drop.

As described in Section 5 and Table 5-2, a single curve was 

fit to all of the “off-the-shelf ” EAC results. An excellent 

correlation between the collected data and the curve fit was 

obtained (r squared value of 0.96), providing the reader with 

an excellent tool for predicting the likely collection efficiency 

of an EAC as a function of particle size.

6.3 Results from Bioaerosol Evaluations of “Offthe-Shelf ” Filters and Electronic Air Cleaners

A select group of filters (seven) and EACs (three) were 

evaluated against a bioaerosol challenge. The purpose of 

the bioaerosol tests was to compare the penetration of a 

bioaerosol to the penetration of a similarly sized inert aerosol 

to determine whether there were any significant differences 

between the penetration of bioaerosol and inert particles.

Similar to previously reported results (RTI, 2004), in nine of 

the ten tests, the measured bioaerosol collection efficiencies 

generally exceeded the average collection efficiency for 

inert particles with physical particle diameters between 0.3 

and 1 μm (E1) but were generally less than or equivalent to 

the inert aerosol collection efficiency results for 1 to 3 μm 

particles (E2). For the remaining filter (6DDUE-8), a low 

(6%) bioaerosol collection efficiency was measured with a 

significant standard deviation. When the standard deviation 

is taken into consideration, the test results are likely in 

reasonable agreement. Overall, the results indicate that 

bioaerosol particles are collected similarly to comparably 

sized inert particles.

6.4 Results from Aging Evaluations of “Off-theShelf ” Filters

For a select group of filters (seven), aging was performed in 

conjunction with inert aerosol testing to examine the effect 

of dust loading in actual use environments on the collection 

efficiencies and pressure drops of the units.

For the two electrostatic residential filters (6DDUE-8 and 

8Nm-10), the collection efficiencies for larger particles (3.0 

to 10.0 μm) either increased significantly (6DDUE-8) or 

remained the same (8Nm-10) after the filters started to be 

loaded with particles. However, for both filters, a substantial 

decrease in collection efficiencies was noted for smaller 

particles (0.3 to 3 μm) after the filters were loaded. The 
79

collection efficiencies of the filters for smaller particles did 

not exceed the initial efficiencies until between 8 and 12 

weeks of loading had occurred. The pressure drops of both 

residential filters remained fairly consistent through the first 

8 weeks of use; the pressure drops then increased greatly 

between Weeks 8 and 12. It should be noted that 12 weeks 

of use constitutes 100% of the manufacturer-recommended 

service time for these two filters.

Similarly, the two electrostatic commercial prefilters 

(C17FPP-8 and C15AAA-11) demonstrated consistent 

average collection efficiencies over the entire 16-week aging 

duration for larger particles (4.0 to 10.0 μm). However, 

there was a very substantial drop in collection efficiencies 

for particles smaller than approximately 4 μm once the 

loading began, and the collection efficiencies for the smaller 

particles never returned to the measured initial values. The 

pressure drops of the prefilters did not demonstrate any 

noticeable increase over the aging period. It should be noted 

that the typical service life for prefilters in the HVAC system 

of interest range from 3 to 6 months, so the 4 months of 

aging that was performed represented between 67% and 

133% of a typical service period. The performance of Filter 

C15AAA-11 was considerably poorer than was specified in 

the manufacturer’s literature.

In contrast, the 12-inch deep electrostatic commercial 

box filter (C8GZ-13) substantially degraded in collection 

efficiency for all particle sizes over the entire aging period, 

dropping steadily from MERV 12 to MERV 10. No change 

in pressure drop occurred over this period, implying that a 

suitable dust cake did not form during loading, which would 

likely have caused the degradation of collection efficiency to 

slow. It should be noted that the typical service life for filter 

C8GZ-13 in the application of interest is 6 to 12 months, 

typically closer to 12 months, so the aging period represented 

only 33% to 67% of the typical service life.

As expected, the two commercial, 12-inch deep, nonelectrostatic, traditional fiberglass media deep-pleated 

filters (C14PCS and C11GM-16) did not demonstrate any 

degradation in collection efficiencies during the aging period. 

In fact, the collection efficiency of Filter C14PCS clearly 

increased as dust was collected on the filter during aging. No 

change in pressure drops was noted over the aging period for 

these two filters. The typical service life for these two filters 

in the application of interest is 6 to 12 months (typically 

closer to 12 months), so the aging period represented only 

33% to 67% of the typical service life.

6.5 Results from Aging Evaluations of “Off-theShelf ” Electronic Air Cleaners

For a select group of EACs (three), aging was performed in 

conjunction with inert aerosol testing to examine the effect 

of dust loading in actual use environments on the collection 

efficiencies and pressure drops of the units. Cleaning was not 

performed over the entire aging duration. This was consistent 

with the manufacturers’ recommendations of cleaning 

intervals between 1 and 6 months in duration. Cleaning was 

recommended in the manufacturers’ literature only 

when a visible inspection indicated that cleaning was

clearly required.

As expected, the pressure drops of all three units remained 

consistent over the entire aging period. By far, Unit A 

demonstrated the least degradation in performance over the 

aging period as it appeared to be operating satisfactorily even 

after 2,016 hours of use without any maintenance. Although 

Unit A did decrease from a MERV 15 to a MERV 14 over the 

aging period, this was due to a minor decrease in the average 

efficiency for 0.3 to 1 μm particles (from 87.6% to 80.7%), 

as the efficiencies in the other particle size ranges remained 

virtually identical.

Unit H also performed reasonably well over the aging 

period but showed more degradation than Unit A, dropping 

from a MERV 15 to a MERV 12. However, the MERV 

rating remained consistent for the first 1,008 hours of 

aging, even though its average efficiency for 0.3 to 1 μm 

particles decreased from 93.4% to 86.8% between 336 and 

1,008 hours of operation. After 2,016 hours of operation, 

its average efficiency for 0.3 to 1 μm particles dropped to 

74.7% and decreased for larger particles as well. Cleaning of 

Unit H after 84 days of continuous operation appeared to be 

warranted.

In contrast, Unit P decreased slightly in collection efficiency 

for particles smaller than 1 μm between 168 and 336 hours 

of use and then dropped precipitously from a MERV 14 

to a MERV 6 between 336 hours and 1,008 hours of use. 

Despite the significant drop in collection efficiency for Unit 

P between 336 hours and 1,008 hours, the visible buildup 

on the unit was not substantial enough to warrant cleaning. 

Unit P was not visibly dirtier than the other two units, so 

the user would have no reason to suspect that performance 

had substantially degraded. However, based on its collection 

efficiency, cleaning of Unit P would be recommended after 

14 days of continuous use.

6.6 Results from Conditioning Evaluations of “Offthe-Shelf ” Filters

Eight electrostatic filters were evaluated using a modified 

inert aerosol test method that involved conditioning with 

submicron potassium chloride particles to identify their 

minimum collection efficiencies, rather than their initial 

collection efficiencies. This modified inert aerosol test 

method was performed in accordance with the latest 

recommendation from ASHRAE, namely draft Addendum 

C to ANSI/ASHRAE Standard 52.2-1999. The purpose of 

these tests was to compare the results from the aging and 

conditioning tests to determine whether draft Addendum C 

provides a means for accurately simulating the performance 

of an electrostatic filter in a typical use environment.

Four of the residential electrostatic filters performed similarly 

during the conditioning evaluations. Upon conditioning, the 

collection efficiencies increased significantly for particles 

larger than approximately 1 to 2 μm but appeared to decrease 

slightly or remain constant for particles smaller than 1 to 
80

2 μm. This was consistent with the observed trend during 

the aging tests of one of the residential filters, in which the 

collection efficiency increased upon aging for particles larger 

than 4 μm but decreased significantly for particles smaller 

than 2 μm. Aging results were not available for comparison 

for the remaining three residential filters.

For a fifth residential filter, the collection efficiency 

decreased slightly for all particles upon initial conditioning 

but increased for all particles once the equivalent of one 

month of conditioning had been performed. This trend 

was similar to the results observed during the aging tests, 

although the decrease was more substantial and required 

approximately 12 weeks of aging to increase past the

initial values.

Similar to those of the residential filters, the aging and 

conditioning tests of a commercial prefilter appeared to 

be consistent. Conditioning of the commercial prefilter 

resulted in a noticeable decrease in collection efficiency 

for all particles less than approximately 1 μm, with no 

recovery during the approximately one month equivalent of 

conditioning. Aging of the prefilter also resulted in a decrease 

(although more substantial) in collection efficiency for all 

particles smaller than approximately 4 μm, with no recovery 

over 16 weeks of aging.

In contrast, the aging and conditioning tests of the remaining 

two commercial filters did not produce consistent results. For 

a commercial prefilter, the collection efficiency increased 

slightly for all particles upon initial conditioning and 

remained at the same level with further conditioning. This 

result noticeably contrasted with the results from the aging 

evaluations, in which the collection efficiency decreased 

substantially for particles smaller than 4 μm with aging and 

did not increase over 16 weeks of use. For a commercial box 

filter, the results from the aging and conditioning evaluations 

contrasted even more strongly. In the conditioning evaluation, 

the collection efficiency remained essentially constant during 

the approximately one month equivalent of conditioning, 

even increasing slightly for particles smaller than 0.3 μm. 

However, during the entire 16 weeks of aging, the box 

filter consistently and continually decreased in collection 

efficiency for all particles.

It is not known why the trends in the results from the 

conditioning evaluations are consistent with the aging 

results for three of the filters but inconsistent with the aging 

results for the other two filters. Further investigation of 

these contrasting results seems warranted but is beyond the 

scope of the present effort. It should be noted that during the 

conditioning evaluations, a single filter was used. In contrast, 

the aging evaluations were performed with five different 

filters of identical make, model, and size. Therefore, some 

variability is present in the aging evaluations due to the 

different performance levels of the individual filters, as well 

as between the filters used in the conditioning evaluation and 

the aging evaluations.

6.7 Results from Conditioning Evaluations of “Offthe-Shelf ” Electronic Air Cleaners

Three EACs were evaluated both before and after 

exposure to silicon vapor. The purpose of the exposure to 

silicon vapor was to compare the results from exposure 

to silicon vapor to the results from the aging tests to 

determine whether the silicon vapor exposure resulted 

in a realistic assessment of the likely performance 

of the EACs after one month of actual use.

The exposure of Units A and P to silicon vapor appeared to 

cause a very similar degradation to that likely observed after 

one month of ambient aging (672 hours of use). For both 

of these units, the collection efficiency of the electronic air 

cleaner degraded more than that observed during 336 hours 

(2 weeks) of ambient use but less than that observed after 

1,008 hours (6 weeks) of ambient use.

For Unit H, however, the silicon vapor exposure degraded 

the unit’s performance well beyond that observed after 

even 2,016 hours of ambient aging (12 weeks of continuous 

operation).

It is not known why the results from the aging and 

conditioning evaluations are consistent for units A and P 

but inconsistent for Unit H. It could be the result of design 

and component differences between the three units. Given 

the approximately 50% decrease in pressure drop in Unit H 

after silicon vapor exposure, and the alteration in the shape 

of the collection efficiency curve, it is possible that the 

exposure allowed leakage to occur within the unit. Further 

investigation of the contrasting results for Unit H seems 

warranted but was beyond the scope of this effort.

It should be noted that in contrast to the filter evaluations, 

during the EAC aging evaluations, a single unit was used. 

Therefore, no variability was present within the EAC aging 

evaluations due to the different performance levels of 

individual units.

6.8 Recommendations

As a result of this effort, curve fits are now available that 

provide a valuable tool enabling researchers/consumers to 

accurately estimate the collection efficiency of a filter or EAC 

(by particle size) with a given mERV rating to determine 

whether its likely performance will justify its increased cost 

and pressure drop. Unfortunately, due to a combination of 

a limited test matrix and some filters that did not perform 

as anticipated, data for filters performing at mERV ratings 

of 9, 11, 13, and 15 were not acquired. Therefore, future 

efforts should be performed to capture data for these mERV 

ratings. In addition, acquiring additional data for filters with 

mERV ratings of 5 and 10 is desirable as only one filter was 

available at that performance rating in the current study.

Also, it was observed during this study that a number of 

filters did not perform in accordance with the mERV ratings 

provided by the filter vendors. Although in many cases, the 

performance was only a few percentage points below the 
81

vendor-provided rating, in some cases, the performance 

was three or four MERV ratings below. The standard for 

establishing MERV ratings (ANSI/ASHRAE 52.2-1999) 

does not currently provide any guidance as to the number of 

samples of a filter type that should be tested to ensure that the 

manufacturer-reported MERV rating provides a statistically 

reasonable representation of their performance. Therefore, 

currently, an evaluation of a single filter could be used to 

characterize the performance of a very large number of 

filters. A study investigating the consistency of performance 

for filters at a given MERV rating is recommended to enable 

consumers to make better-informed decisions about the likely 

performance of purchased filters.

In this study, EACs appeared to be an excellent choice for 

residential air cleaning as they provided substantially higher 

collection efficiencies than are available from residential 

filters, at a fraction of the pressure drop. Evaluations of their 

performance to better define the likely frequency of cleaning 

and the collection efficiency performance as a function of the 

number of cleaning cycles are needed to compare the longterm operational costs of EACs to that of air filters.

The results from this study indicated that the conditioning 

procedures for electrostatic filters described in Addendum C 

of ANSI/ASHRAE 52.2-1999 warrant additional 

investigation. Although the results from aging and 

conditioning via Addendum C demonstrated similar trends 

for residential electrostatic filters, the results from the 

commercial filters contrasted strongly.

Similarly, the silicon vapor exposure conditioning method 

that was investigated for EACs would benefit from additional 

study. For two of the three units evaluated, the results 

between the aging and conditioning methodology showed 

very good agreement; however, for the third unit, the results 

contrasted significantly. While these results seem promising 

for the silicon vapor exposure method, additional study and 

refinement seem warranted.

For the inert particles, size measurements were made using 

a light-scattering technique (0.3 to 10 μm) and a technique 

based on electrical mobility (0.03 to 0.3 μm). In general, 

the collection efficiency measured at the lowest size bin 

for the larger range (0.35 μm midpoint) was within 10% 

of the highest size bin of the smaller size range (0.294 μm 

midpoint). Often, the agreement was much closer. However, 

to our knowledge a study to assess the agreement between 

the two measurement methods in a range of overlapping 

particle sizes has not been performed. It is recommended that 

research be performed to investigate the differences between 

these different measurement techniques in the overlapping 

size range.
82

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83

7.0

References

ANSI/ASHRAE (American National Standards Institute/American Society of Heating, Refrigerating and AirConditioning Engineers), 1999. ANSI/ASHRAE Standard 52.2-1999, Method of Testing General Ventilation 

Air-Cleaning Devices for Removal Efficiency by Particle Size, Atlanta, GA.

Battelle Memorial Institute, 2005a. “Test/Quality Assurance Plan for Task 2: Development of Performance 

Information for Common Ventilation Filters.” Report to the U.S. Environmental Protection Agency

(April 4, 2005).

Battelle Memorial Institute, 2005b. “Test/Quality Assurance Plan for Task 3: Development of Performance 

Information for Electronic Air Cleaners.” Report to the U.S. Environmental Protection Agency (June 21, 2005).

Hanley, J.T., D.S. Ensor, and D.L. Franke. “Environmental Technology Verification Draft Test Protocol for 

Electronic Air Cleaners.” Performed by Research Triangle Institute, Research Triangle Park, North Carolina 

under EPA Cooperative Agreement CR 822870 (2002).

Hanley, J.T., and M.K. Owen. “Develop a New Loading Dust and Dust Loading Procedures for the ASHRAE 

Filter Test Standards 52.1 and 52.2.” Performed by Research Triangle Institute, Research Triangle Park, North 

Carolina under ASHRAE Project Number 1190-RP (2003).

The McIlvaine Company, 2002, “World Air Filtation and Purification Market 1999–2004.” The McIlvaine 

Company, Northbrook, Illinois, U.S.A. (www.mcilvainecompany.com).

RTI, 2004. “Environmental Technology Verification: Test Report of Filtration Efficiency of Bioaerosols in 

HVAC Systems.” Performed by Research Triangle Institute, Research Triangle Park, North Carolina under EPA 

Contract Number GS10F0283K-BPA-1, Task Order 1101. 
84

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A-1

Appendix A

Sample Calculations From the Inert Aerosol Tests

Table A-1. Example Correlation Ratio Calculation (Filter IPP-6-1)

OPC Channel # 1 2 3 4 5 6 7 8 9 10 11 12

Geo. Mean Dia. (μm) 0.35 0.47 0.62 0.84 1.14 1.44 1.88 2.57 3.46 4.69 6.20 8.37

Upstream – Bkg 22 31 22 49 21 12 34 18 13 13 2 5

Upstream – Bkg 27 70 50 96 29 19 23 32 17 9 2 3

Upstream – Bkg 12 28 18 18 10 5 6 6 5 4 1 3

Upstream – Bkg 4 8 4 6 3 3 5 5 9 4 1 1

Upstream – Bkg 7 6 5 9 0 0 5 2 3 3 0 0

Upstream – Bkg 3 17 11 19 6 8 4 12 6 2 0 1

Upstream 6057 6920 3710 8115 3000 1694 2389 2827 1615 901 235 91

Upstream 6601 7633 4069 8856 3256 1875 2667 3186 1844 1049 285 116

Upstream 6812 7968 4113 9175 3279 1937 2758 3252 1890 1116 299 113

Upstream 6906 8068 4145 9329 3375 2004 2764 3243 1881 1114 305 109

Upstream 7022 8022 4240 9414 3458 1990 2773 3242 1866 1114 302 118

Upstream 7174 7969 4236 9583 3411 1993 2769 3311 1910 1093 286 119

Upstream 7324 8208 4279 9794 3482 2095 2833 3469 1985 1074 304 115

Upstream 7255 8322 4361 9747 3558 2061 2860 3406 1967 1097 318 115

Upstream 7299 8439 4366 9905 3549 2063 2882 3397 1966 1114 303 114

Upstream 7318 8376 4344 9784 3482 2029 2902 3428 1984 1099 295 111

Upstream 7176 8167 4370 9591 3461 1998 2915 3398 1956 1071 298 117

Upstream – Bkg 16 30 26 50 6 7 9 11 6 2 3 1

Upstream – Bkg 18 35 48 75 23 12 22 40 16 14 7 9

Upstream – Bkg 3 0 1 5 3 2 5 2 4 3 1 0

Upstream – Bkg 14 15 3 13 7 3 9 10 7 4 2 1

Upstream – Bkg 15 21 19 16 9 1 8 6 5 3 2 3

Upstream – Bkg 12 32 13 36 22 11 8 8 1 2 0 1

Average Ub 12.75 24.42 18.33 32.67 11.58 6.92 11.50 12.67 7.67 5.25 1.75 2.33

Std. Dev Ub 7.59 18.33 16.39 29.36 9.56 5.70 9.53 11.90 5.10 4.29 1.91 2.57

Ub, ucl 17.57 36.06 28.75 51.32 17.66 10.54 17.55 20.23 10.91 7.97 2.97 3.97

Avg. Uc 6995 8008 4203 9390 3392 1976 2774 3287 1896 1076 293 112

Ub, ucl/Avg. Uc 0.0025 0.0045 0.0068 0.0055 0.0052 0.0053 0.0063 0.0062 0.0058 0.0074 0.0101 0.0354

Downstream – Bkg 9 14 9 21 5 4 3 0 4 0 0 0

Downstream – Bkg 1 1 1 7 0 1 0 0 0 0 0 0

Downstream – Bkg 3 7 5 11 4 1 5 3 3 1 1 0

Downstream – Bkg 8 21 19 44 12 18 27 22 14 11 1 6

Downstream – Bkg 8 12 10 12 8 3 6 8 4 2 2 0

Downstream – Bkg 3 10 5 9 2 4 2 3 1 2 0 1

Downstream 6206 6849 3638 8126 3085 1696 2503 2901 1672 959 250 103

Downstream 6543 7481 3993 8798 3260 1937 2580 3244 1832 1031 296 116

Downstream 6758 7576 4028 9255 3239 1913 2648 3234 1863 1055 296 132

Downstream 7162 8011 4195 9447 3445 1996 2922 3304 1888 1141 289 112

Downstream 7155 8106 4131 9281 3447 2014 2818 3313 1861 1080 286 113

Downstream 7051 7978 4124 9198 3394 1958 2722 3298 1907 1090 295 104

Downstream 7158 8151 4203 9406 3535 2017 2919 3346 1932 1112 297 138

Downstream 7231 8246 4385 9598 3499 2093 2737 3351 1859 1090 307 132

Downstream 7103 8176 4177 9407 3371 2021 2813 3221 1844 1028 290 133

Downstream 7356 8516 4338 10027 3612 2028 2960 3472 2000 1105 320 130

Downstream 7025 7877 4222 9283 3349 1935 2798 3325 1881 1070 291 138

Downstream – Bkg 7 12 5 15 3 2 2 3 2 1 0 0

Downstream – Bkg 2 4 1 7 2 1 1 1 1 0 0 0

Downstream – Bkg 2 0 2 2 2 0 6 2 0 1 0 0

Downstream – Bkg 3 5 6 4 0 1 1 1 0 0 1 0

Downstream – Bkg 2 2 3 1 1 2 4 3 0 0 0 0

Downstream – Bkg 13 10 5 4 6 2 3 2 0 1 0 0

Average Db 5.08 8.17 5.92 11.42 3.75 3.25 5.00 4.00 2.42 1.58 0.42 0.58

Std. Dev Db 3.78 6.18 4.98 11.75 3.55 4.81 7.20 6.05 3.96 3.06 0.67 1.73

Db, ucl 7.48 12.09 9.08 18.88 6.00 6.30 9.57 7.84 4.94 3.53 0.84 1.68

Db, ucl/Avg. Uc 0.0011 0.0015 0.0022 0.0020 0.0018 0.0032 0.0035 0.0024 0.0026 0.0033 0.0029 0.0150

R 0.999 0.989 0.986 0.989 1.001 0.996 1.000 0.999 0.988 0.998 1.004 1.115

Std Dev. R 0.0212 0.0199 0.0167 0.0247 0.0263 0.0211 0.0377 0.0260 0.0290 0.0401 0.0491 0.1131

Std. Dev. R*t/n0.5 0.0142 0.0133 0.0112 0.0166 0.0177 0.0142 0.0253 0.0174 0.0195 0.0269 0.0330 0.0760
A-2

Table A-2. Example Penetration Calculation (Filter IPP-6-1)

OPC Channel # 1 2 3 4 5 6 7 8 9 10 11 12

Geo. Mean Dia. (μm) 0.35 0.47 0.62 0.84 1.14 1.44 1.88 2.57 3.46 4.69 6.20 8.37

Upstream – Bkg 167 239 163 248 112 82 84 84 48 18 2 11

Upstream – Bkg 27 36 20 47 13 13 13 15 8 5 1 2

Upstream – Bkg 13 13 10 26 4 11 7 5 0 2 1 0

Upstream – Bkg 4 3 3 2 1 0 2 3 2 0 0 0

Upstream – Bkg 3 17 7 9 5 1 3 3 0 1 1 0

Upstream – Bkg 11 8 3 6 4 1 3 3 0 0 0 0

Upstream 6034 6713 3534 7736 2911 1639 2111 2225 1080 505 120 38

Upstream 6836 7655 4007 8799 3310 1843 2395 2604 1275 564 137 44

Upstream 6909 7778 4085 8947 3380 1915 2413 2656 1302 568 138 40

Upstream 6804 7680 4049 8942 3247 1903 2379 2570 1262 569 123 38

Upstream 6733 7650 4015 8813 3175 1803 2335 2523 1252 556 118 34

Upstream 6787 7640 3940 8786 3267 1770 2343 2504 1261 570 137 42

Upstream 6936 7656 4012 8874 3312 1776 2349 2536 1237 556 145 52

Upstream 7027 7784 4208 8886 3375 1881 2377 2571 1244 549 143 41

Upstream 6983 7838 4220 9002 3406 1940 2412 2596 1307 567 138 37

Upstream 6972 7855 4196 9163 3385 1887 2415 2603 1293 565 136 45

Upstream 6973 7833 4171 9070 3322 1885 2369 2573 1250 568 134 44

Upstream – Bkg 12 9 10 18 8 4 12 8 1 0 1 0

Upstream – Bkg 5 16 8 15 6 6 7 4 2 0 1 0

Upstream – Bkg 6 4 0 5 1 1 1 2 1 0 0 0

Upstream – Bkg 4 4 0 4 2 3 0 2 1 0 0 0

Upstream – Bkg 5 6 6 6 4 2 3 6 0 0 0 0

Upstream – Bkg 4 2 5 9 2 2 2 2 6 4 0 1

Average Ub 21.75 29.75 19.58 32.92 13.50 10.50 11.42 11.42 5.75 2.50 0.58 1.17

Std. Dev Ub 46.24 66.56 45.49 68.90 31.20 22.89 23.24 23.15 13.55 5.18 0.67 3.16

Ub, ucl 51.13 72.04 48.48 76.69 33.32 25.04 26.18 26.13 14.36 5.79 1.01 3.17

Avg. Ut 6817 7644 4040 8820 3281 1840 2354 2542 1251 558 133 41

Ub, ucl/Avg. Ut 0.0075 0.0094 0.0120 0.0087 0.0102 0.0136 0.0111 0.0103 0.0115 0.0104 0.0076 0.0771

Downstream – Bkg 9 3 1 3 1 2 4 7 2 0 0 0

Downstream – Bkg 5 8 5 10 2 5 1 0 1 0 0 0

Downstream – Bkg 4 0 0 2 0 1 0 0 0 0 0 0

Downstream – Bkg 5 7 4 6 1 1 3 1 0 0 0 0

Downstream – Bkg 14 4 3 2 0 0 0 1 0 0 0 0

Downstream – Bkg 6 3 1 0 0 1 1 2 0 0 0 0

Downstream 5655 6366 3420 6695 2288 1161 1346 1325 727 330 94 25

Downstream 6569 7358 3873 7574 2502 1253 1526 1601 765 404 91 25

Downstream 6727 7461 3800 7679 2571 1315 1541 1603 830 372 92 31

Downstream 6470 7205 3825 7618 2533 1249 1476 1472 789 361 81 28

Downstream 6310 6957 3646 7256 2397 1192 1397 1383 704 363 89 22

Downstream 6541 7565 3746 7600 2529 1283 1528 1488 773 387 78 41

Downstream 6606 7273 3635 7447 2454 1245 1427 1460 745 346 92 35

Downstream 6912 7855 3930 8119 2686 1374 1502 1610 792 387 105 37

Downstream 6983 7828 3980 8035 2655 1359 1511 1633 872 351 116 36

Downstream 6675 7395 3792 7773 2486 1237 1495 1465 735 359 101 24

Downstream 6783 7589 3965 7702 2486 1247 1470 1459 787 388 81 26

Downstream – Bkg 6 3 2 7 1 1 1 3 1 1 0 0

Downstream – Bkg 6 5 4 7 0 2 1 2 0 0 0 0

Downstream – Bkg 5 5 3 6 0 1 0 0 0 0 0 0

Downstream – Bkg 6 1 1 2 1 1 0 0 0 0 0 0

Downstream – Bkg 6 2 2 3 1 0 0 0 0 0 0 0

Downstream – Bkg 8 4 6 3 0 0 1 1 0 0 0 0

Average Db 6.67 3.75 2.67 4.25 0.58 1.25 1.00 1.42 0.33 0.08 0.00 0.00

Std. Dev Db 2.67 2.30 1.83 2.90 0.67 1.36 1.28 2.02 0.65 0.29 0.00 0.00

Db, ucl 8.37 5.21 3.83 6.09 1.01 2.11 1.81 2.70 0.75 0.27 0.00 0.00

Db, ucl/Avg. Ut 0.0012 0.0007 0.0009 0.0007 0.0003 0.0011 0.0008 0.0011 0.0006 0.0005 0.0000 0.0000

Pobserved 0.9649 0.9646 0.9408 0.8635 0.7677 0.6912 0.6290 0.5922 0.6223 0.6629 0.6998 0.7558

Std Dev. Pobserved 0.0190 0.0292 0.0231 0.0248 0.0199 0.0275 0.0154 0.0269 0.0356 0.0326 0.0828 0.1634

R (from Table A-1) 0.999 0.989 0.986 0.989 1.001 0.996 1.000 0.999 0.988 0.998 1.004 1.115

Pcorrected 0.9657 0.9751 0.9544 0.8735 0.7670 0.6938 0.6289 0.5925 0.6296 0.6641 0.6972 0.6779

Filtration Efficiency (%) 3.4 2.5 4.6 12.7 23.3 30.6 37.1 40.8 37.0 33.6 30.3 32.2
B-1

Appendix B

Sample Calculations From the Bioaerosol Tests

Table B-1. Example Bioaerosol P100 Calculation (820 cfm flow rate) with no filter in the system

Sample

CFU/mL in 

sample

Total CFU in 

sample

Sampling 

flow rate 

(lpm)

Sampling 

Duration 

(min)

CFU/liter of 

air

Average 

Concentration 

(CFU/liter of air) Std. Dev.

Coefficent of 

Variance

Upstream 4.23*104 4.23*105 7.342 10 5.76*103 5.24*103 5.3*102 10%

Upstream 4.18*104 4.18*105 7.368 10 5.68*103

Upstream 4.15*104 4.15*105 7.380 10 5.63*103

Upstream 3.43*104 3.43*105 7.275 10 4.72*103

Upstream 3.35*104 3.35*105 7.347 10 4.56*103

Upstream 3.78*104 3.78*105 7.271 10 5.20*103

Upstream 3.49*104 3.49*105 7.420 10 4.70*103

Upstream 3.63*104 3.63*105 7.325 10 4.96*103

Upstream 4.26*104 4.26*105 7.164 10 5.95*103

Downstream 3.87*104 3.87*105 7.211 10 5.37*103 5.21*103 3.7*102 7%

Downstream 3.88*104 3.88*105 7.439 10 5.22*103

Downstream 3.86*104 3.86*105 7.415 10 5.21*103

Downstream 3.95*104 3.95*105 7.415 10 5.33*103

Downstream 4.05*104 4.05*105 7.602 10 5.33*103

Downstream 4.20*104 4.20*105 7.321 10 5.74*103

Downstream 3.56*104 3.56*105 7.362 10 4.84*103

Downstream 3.22*104 3.22*105 7.257 10 4.44*103

Downstream 3.94*104 3.94*105 7.234 10 5.45*103

Background <2*101 <2*102 ~7.4 10 <2.7

Background <2*101 <2*102 ~7.2 10 <2.8

Pmeasured 0.995

Table B-2. Example Bioaerosol Calculation (Filter 8NM-10-12)

Sample

CFU/mL 

in sample

Total CFU 

in sample

Sampling 

flow rate 

(lpm)

Sampling 

Duration 

(min)

CFU/liter 

of air

Average 

Concentration 

(CFU/liter of air) Std. Dev.

Coefficient of 

Variance

Upstream 4.02*104 4.02*105 7.468 10 5.38*103 4.91*103 4.40*102 9%

Upstream 3.44*104 3.44*105 7.496 10 4.59*103

Upstream 4.26*104 4.26*105 7.417 10 5.75*103

Upstream 3.68*104 3.68*105 7.348 10 5.01*103

Upstream 3.43*104 3.43*105 7.443 10 4.61*103

Upstream 3.52*104 3.52*105 7.358 10 4.78*103

Upstream 3.64*104 3.64*105 7.534 10 4.83*103

Upstream 3.20*104 3.20*105 7.476 10 4.28*103

Upstream 3.59*104 3.59*105 7.298 10 4.92*103

Downstream 2.18*104 2.18*105 7.355 10 2.97*103 2.93*103 1.68*102 6%

Downstream 2.19*104 2.19*105 7.601 10 2.88*103

Downstream 2.13*104 2.13*105 7.564 10 2.82*103

Downstream 1.99*104 1.99*105 7.571 10 2.62*103

Downstream 2.24*104 2.24*105 7.677 10 2.92*103

Downstream 2.19*104 2.19*105 7.467 10 2.93*103

Downstream 2.17*104 2.17*105 7.488 10 2.90*103

Downstream 2.37*104 2.37*105 7.376 10 3.21*103

Downstream 2.30*104 2.30*105 7.365 10 3.12*103

Background <2*101 <2*102 7.564 10 <2.7

Background <2*101 <2*102 7.358 10 <2.8

Pmeasured 0.597

P100 (from Table B-1) 0.995

Pcorrected 0.600

Filtration Efficiency 40%

Combined Standard 

Deviation

6%
B-2

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C-1

Appendix C

Additional Information on Aging of Filters

During The In-Use Tests

Filter

Figure C-1. Photograph of Residential HVAC System Used to Age 

Filter 6DDUE-8

Table C-1. Basic Information on Residential HVAC System Used to Age Filter 6DDUE-8

Approximate House Size (sq. ft) ~2200 sq. ft.

HVAC System Make/Model Atlas Butler

Approximate Age of HVAC System 1 year

Type of Flooring Carpet

Number and Type of Pets 1 mid-size dog

Number of Adults/Kids in Household 2 adults/0 children
C-2

Figure C-2. Photograph of Residential HVAC System Used to 

Age Filter 8NM-10

Filter

Table C-2. Basic Information on Residential HVAC System Used to Age Filter 8NM-10

Approximate House Size (sq. ft) 2800 sq ft.

HVAC System Make/Model Carrier

Approximate Age of HVAC System 33 years

Type of Flooring Carpet

Number and Type of Pets None

Number of Adults/Kids in Household 2 adults/3 children
C-3

Figure C-3. Photograph of 40-Filter Commercial HVAC System Used to Age Filters C17FPP-8, 

C15AAA-11, and C8GZ-13 (C8GZ-13 Filters were inserted behind the prefilters in the 

gaps shown.)
C-4

Figure C-4. Photograph of 40-Filter Commercial HVAC System Used to Age Filters C17FPP-8, 

C15AAA-11, and C8GZ-13 (The five C17FPP-8 and five C15AAA-11 filters are in the center.)
C-5

Figure C-5. Photograph of the 9-Filter Commercial HVAC System Used to Age Filters C14PCS and 

C11GM-16 (The test filters are shown before the prefilters were installed.)
C-6

Figure C-6. Photograph of the 9-Filter Commercial HVAC System Used to Age Filters C14PCS and 

C11GM-16 (The test filters are behind the prefilters.)
D-1

Appendix D

Photographs of the Various Test Systems Utilized 

During Inert Aerosol Testing, Bioaerosol Testing, 

Aging of Electronic Air Cleaners, and Exposure of 

Electronic Air Cleaners

Figure D-1. Photograph of the Upstream Side of Intertek’s ASHRAE 52.2-1999 Inert 

Aerosol Test System Used During the Inert Aerosol Tests and Electrostatic 

Conditioning Tests
D-2

Figure D-2. Photograph of the Downstream Side of Intertek’s ASHRAE 52.2-1999 

Inert Aerosol Test System Used During the Inert Aerosol Tests and 

Electrostatic Conditioning Tests

Figure D-3. Photograph of the Test Fixture Used During the Bioaerosol Tests
D-3

Figure D-4. Photograph of the Air Intake of the Bioaerosol Test Fixture

Figure D-5. Photograph (side view) of the Test Fixture Used During the Silicon 

Vapor Exposures of the Electronic Air Cleaners
D-4

Figure D-6. Photograph (interior) of the Test Fixture Used During the Silicon Vapor 

Exposures of the Electronic Air Cleaners

Figure D-7. Photograph of the Downstream Side and Blower of the Test Fixture Used 

During the Ambient Aging of the Electronic Air Cleaners
D-5

Figure D-8. Photograph of the Upstream Side of the Test Fixture and Airflow 

Controllers Used During the Ambient Aging of the Electronic Air Cleaners
D-6

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E-1

Appendix E

Results From the Inert Aerosol Evaluations of

“Off-the-Shelf ” Air Cleaners

Table E-1. Initial Measured Collection Efficiency and Pressure Drop of a Residential 16" x 25" x 1"

Pleated Non-Electrostatic Filter (IPP-6-1)

Particle Size 

Range or Midpoint 

of Range (μm)

Particle Size 

Efficiency (%) Airflow Rate (cfm) Air Velocity (fpm)

Measured 

Pressure Drop (in. 

w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 7.6 430 155 0.08 0.07 @ 147 fpm

0.034 8.6 625 225 0.12 0.13 @ 221 fpm

0.039 2.2 833 300 0.18 0.18 @ 295 fpm

0.045 3.1 1041 375 0.24 0.25 @ 368 fpm

0.052 3.8

0.060 1.1

0.070 0

0.081 2.0

0.093 0

0.11 0

0.12 1.8

0.14 2.7

0.17 0.9

0.19 2.7

0.22 0

0.26 0

0.29 0

0.30 – 0.40 3.4

0.40 – 0.55 2.5

0.55 – 0.70 4.6

0.70 – 1.00 12.7

1.00 – 1.30 23.3

1.30 – 1.60 30.6

1.60 – 2.20 37.1

2.20 – 3.00 40.8

3.00 – 4.00 37

4.00 – 5.50 33.6

5.50 – 7.00 30.3

7.00 – 10.00 32.2

E1 (0.30 – 1.0) 5.8

E2 (1.0 – 3.0) 33.0

E3 (3.0 – 10.0) 33.3

MERV rating from 

vendor

6

MERV rating from 

testing

5
E-2

Table E-2. Initial Measured Collection Efficiency and Pressure Drop of a Residential 16" x 25" x 1"

Pleated Non-Electrostatic Filter (2NS-8-1)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 1.7 410 148 0.07 NA

0.034 2.2 615 221 0.13 NA

0.039 0.0 820 295 0.19 NA

0.045 0.4 1025 369 0.26 NA

0.052 0.7

0.060 0.5

0.070 0.4

0.081 0.0

0.093 0.9

0.11 4.8

0.12 0.4

0.14 1.9

0.17 0.0

0.19 1.0

0.22 4.8

0.26 1.9

0.29 5.1

0.30 – 0.40 8.0

0.40 – 0.55 9.7

0.55 – 0.70 4.9

0.70 – 1.00 0.8

1.00 – 1.30 5.0

1.30 – 1.60 8.3

1.60 – 2.20 18.2

2.20 – 3.00 31.1

3.00 – 4.00 39.2

4.00 – 5.50 43.0

5.50 – 7.00 42.6

7.00 – 10.00 40.4

E1 (0.30 – 1.0) 5.9

E2 (1.0 – 3.0) 15.7

E3 (3.0 – 10.0) 41.3

MERV rating from vendor 8

MERV rating from testing 6
E-3

Table E-3. Initial Measured Collection Efficiency and Pressure Drop of a Residential 16" x 25" x 1"

Pleated Electrostatic Filter (3PAF-11-1)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 44.2 410 148 0.04 NA

0.034 42.8 615 221 0.12 NA

0.039 42.6 820 295 0.18 0.20 @ 306 fpm

0.045 40.1 1025 369 0.26 0.32 @ 504 fpm

0.052 37.0

0.060 34.8

0.070 33.2

0.081 31.2

0.093 29.2

0.11 28.0

0.12 27.8

0.14 26.1

0.17 26.2

0.19 23.6

0.22 24.1

0.26 25.9

0.29 26.0

0.30 – 0.40 23.1

0.40 – 0.55 24.5

0.55 – 0.70 23.3

0.70 – 1.00 22.4

1.00 – 1.30 26.3

1.30 – 1.60 30.6

1.60 – 2.20 39.8

2.20 – 3.00 55.1

3.00 – 4.00 68.0

4.00 – 5.50 79.6

5.50 – 7.00 88.5

7.00 – 10.00 92.5

E1 (0.30 – 1.0) 23.3

E2 (1.0 – 3.0) 37.9

E3 (3.0 – 10.0) 82.1

MERV rating from vendor 11

MERV rating from testing 8
E-4

Table E-4. Initial Measured Collection Efficiency and Pressure Drop of a Residential 16" x 25" x 1"

Pleated Electrostatic Filter (4FUA-12-1)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 48.3 410 148 0.04 NA

0.034 50.8 615 221 0.07 NA

0.039 49.3 820 295 0.09 NA

0.045 48.2 1025 369 0.13 NA

0.052 46.0

0.060 43.9

0.070 42.1

0.081 40.7

0.093 40.1

0.11 38.3

0.12 36.5

0.14 34.8

0.17 33.0

0.19 32.0

0.22 34.7

0.26 32.4

0.29 34.8

0.30 – 0.40 30.4

0.40 – 0.55 32.1

0.55 – 0.70 41.2

0.70 – 1.00 55.0

1.00 – 1.30 69.8

1.30 – 1.60 77.7

1.60 – 2.20 86.2

2.20 – 3.00 89.5

3.00 – 4.00 90.4

4.00 – 5.50 90.4

5.50 – 7.00 93.3

7.00 – 10.00 94.3

E1 (0.30 – 1.0) 39.7

E2 (1.0 – 3.0) 80.8

E3 (3.0 – 10.0) 92.1

MERV rating from vendor 12

MERV rating from testing 12
E-5

Table E-5. Initial Measured Collection Efficiency and Pressure Drop of a Residential 16" x 25" x 1"

Pleated Electrostatic Filter (5RM-11-1)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 35.5 410 148 0.10 0.06 @ 125 fpm

0.034 31.8 615 221 0.17 0.12 @ 250 fpm

0.039 27.5 820 295 0.25 NA

0.045 26.5 1025 369 0.34 0.19 @ 375 fpm

0.052 23.6

0.060 22.3

0.070 19.7

0.081 17.5

0.093 16.0

0.11 15.7

0.12 14.9

0.14 11.8

0.17 12.3

0.19 9.4

0.22 12.6

0.26 8.7

0.29 15.7

0.30 – 0.40 14.7

0.40 – 0.55 11.7

0.55 – 0.70 17.1

0.70 – 1.00 33.3

1.00 – 1.30 52.9

1.30 – 1.60 62.5

1.60 – 2.20 71.2

2.20 – 3.00 72.9

3.00 – 4.00 69.4

4.00 – 5.50 66.5

5.50 – 7.00 68.2

7.00 – 10.00 70.4

E1 (0.30 – 1.0) 19.2

E2 (1.0 – 3.0) 64.9

E3 (3.0 – 10.0) 68.7

MERV rating from vendor 11

MERV rating from testing 7
E-6

Table E-6. Initial Measured Collection Efficiency and Pressure Drop of a Residential 16" x 25" x 1"

Pleated Electrostatic Filter (6DDUE-8)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 25.0 410 148 0.06 0.07 @ 148 fpm

0.034 33.8 615 221 0.10 0.12 @ 221 fpm

0.039 30.8 820 295 0.14 0.17 @ 295 fpm

0.045 28.0 1025 369 0.19 0.23 @ 369 fpm

0.052 27.1

0.060 25.7

0.070 23.0

0.081 22.3

0.093 22.3

0.11 23.6

0.12 23.3

0.14 23.2

0.17 21.8

0.19 25.4

0.22 25.3

0.26 18.2

0.29 18.1

0.30 – 0.40 16.1

0.40 – 0.55 14.0

0.55 – 0.70 21.4

0.70 – 1.00 31.1

1.00 – 1.30 44.8

1.30 – 1.60 50.6

1.60 – 2.20 55.6

2.20 – 3.00 56.8

3.00 – 4.00 57.6

4.00 – 5.50 55.5

5.50 – 7.00 59.2

7.00 – 10.00 54.9

E1 (0.30 – 1.0) 20.6

E2 (1.0 – 3.0) 51.9

E3 (3.0 – 10.0) 56.8

MERV rating from vendor 8

MERV rating from testing 7
E-7

Table E-7. Initial Measured Collection Efficiency and Pressure Drop of a Residential 16" x 25" x 1"

Pleated Electrostatic Filter (7AST-8-3)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 37.2 410 148 0.11 NA

0.034 36.6 615 221 0.19 NA

0.039 33.7 820 295 0.29 NA

0.045 31.8 1025 369 0.41 NA

0.052 30.3

0.060 28.6

0.070 26.7

0.081 23.9

0.093 22.6

0.11 22.8

0.12 20.4

0.14 20.5

0.17 22.5

0.19 21.6

0.22 21.0

0.26 23.8

0.29 18.3

0.30 – 0.40 9.4

0.40 – 0.55 10.8

0.55 – 0.70 19.6

0.70 – 1.00 36.2

1.00 – 1.30 54.2

1.30 – 1.60 61.7

1.60 – 2.20 67.5

2.20 – 3.00 66.9

3.00 – 4.00 64.2

4.00 – 5.50 60.4

5.50 – 7.00 62.9

7.00 – 10.00 57.8

E1 (0.30 – 1.0) 19.0

E2 (1.0 – 3.0) 62.6

E3 (3.0 – 10.0) 61.3

MERV rating from vendor 8

MERV rating from testing 7
E-8

Table E-8. Initial Measured Collection Efficiency and Pressure Drop of a Residential 16" x 25" x 1"

Pleated Electrostatic Filter (8NM-10)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm)

Air Velocity 

(fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 22.7 410 148 0.17 NA

0.034 20.2 615 221 0.29 NA

0.039 18.5 820 295 0.43 NA

0.045 17.9 1025 369 0.59 NA

0.052 15.5

0.060 13.8

0.070 13.1

0.081 13.1

0.093 11.8

0.11 10.8

0.12 9.4

0.14 10.6

0.17 10.0

0.19 7.9

0.22 13.6

0.26 12.6

0.29 18.0

0.30 – 0.40 16.9

0.40 – 0.55 20.5

0.55 – 0.70 33.8

0.70 – 1.00 53.7

1.00 – 1.30 72.4

1.30 – 1.60 80.4

1.60 – 2.20 86.8

2.20 – 3.00 89.8

3.00 – 4.00 91.0

4.00 – 5.50 91.5

5.50 – 7.00 91.3

7.00 – 10.00 91.8

E1 (0.30 – 1.0) 31.2

E2 (1.0 – 3.0) 82.4

E3 (3.0 – 10.0) 91.4

MERV rating from vendor 10

MERV rating from testing 12
E-9

Table E-9. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 2"

Pleated Non-Electrostatic Filter (C1APP-7)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 22.1 984 246 0.10 NA

0.034 19.5 1476 369 0.18 0.12 @ 300 fpm

0.039 18.1 1968 492 0.28 0.28 @ 500 fpm

0.045 15.4 2460 615 0.41 0.43 @ 625 fpm

0.052 13.7

0.060 13.3

0.070 12.6

0.081 10.2

0.093 10.0

0.11 11.6

0.12 8.7

0.14 12.1

0.17 9.9

0.19 12.9

0.22 11.6

0.26 12.7

0.29 16.4

0.30 – 0.40 1.7

0.40 – 0.55 4.5

0.55 – 0.70 2.2

0.70 – 1.00 9.2

1.00 – 1.30 15.5

1.30 – 1.60 18.7

1.60 – 2.20 26.0

2.20 – 3.00 37.2

3.00 – 4.00 44.8

4.00 – 5.50 48.8

5.50 – 7.00 53.1

7.00 – 10.00 52.2

E1 (0.30 – 1.0) 4.4

E2 (1.0 – 3.0) 24.3

E3 (3.0 – 10.0) 49.7

MERV rating from vendor 7

MERV rating from testing 6
E-10

Table E-10. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 2"

Non-Pleated Non-Electrostatic Filter (C2T90-8)

(

a

 – No appreciable collection efficiency was measured in three separate tests.)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 0.0a 984 246 0.15 NA

0.034 0.0a 1476 369 0.27 0.25 @ 300 fpm

0.039 0.0a 1968 492 0.41 0.50 @ 500 fpm

0.045 0.0a 2460 615 0.57 NA

0.052 0.0a

0.060 0.0a

0.070 0.0a

0.081 0.0a

0.093 0.0a

0.11 0.0a

0.12 0.0a

0.14 0.0a

0.17 0.0a

0.19 0.0a

0.22 0.0a

0.26 0.0a

0.29 0.0a

0.30 – 0.40 5.4

0.40 – 0.55 10.4

0.55 – 0.70 17.7

0.70 – 1.00 26.4

1.00 – 1.30 32.3

1.30 – 1.60 38.1

1.60 – 2.20 48.1

2.20 – 3.00 61.3

3.00 – 4.00 63.8

4.00 – 5.50 56.7

5.50 – 7.00 50.0

7.00 – 10.00 35.2

E1 (0.30 – 1.0) 15.0

E2 (1.0 – 3.0) 44.9

E3 (3.0 – 10.0) 51.4

MERV rating from vendor 8

MERV rating from testing 7
E-11

Table E-11. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 4"

Pleated Non-Electrostatic Box Filter (C3AV-11)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 59.5 984 246 0.16 0.16 @ 250 fpm

0.034 56.0 1476 369 0.29 0.29 @ 375 fpm

0.039 53.1 1968 492 0.46 0.45 @ 500 fpm

0.045 47.9 2460 615 0.65 0.63 @ 625 fpm

0.052 43.6

0.060 41.2

0.070 38.5

0.081 36.5

0.093 37.0

0.11 35.4

0.12 36.2

0.14 34.0

0.17 35.6

0.19 36.1

0.22 36.6

0.26 36.3

0.29 37.5

0.30 – 0.40 25.0

0.40 – 0.55 33.2

0.55 – 0.70 34.2

0.70 – 1.00 45.0

1.00 – 1.30 52.2

1.30 – 1.60 55.3

1.60 – 2.20 61.0

2.20 – 3.00 77.6

3.00 – 4.00 86.1

4.00 – 5.50 91.6

5.50 – 7.00 95.7

7.00 – 10.00 96.4

E1 (0.30 – 1.0) 34.3

E2 (1.0 – 3.0) 61.5

E3 (3.0 – 10.0) 92.5

MERV rating from vendor 11

MERV rating from testing 10
E-12

Table E-12. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 12"

Pleated Non-Electrostatic Filter (C4FPC-11)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 41.7 984 246 0.13 0.15 @ 250 fpm

0.034 36.6 1476 369 0.23 0.20 @ 375 fpm

0.039 30.3 1968 492 0.36 0.30 @ 500 fpm

0.045 27.4 2460 615 0.52 0.40 @ 625 fpm

0.052 23.1

0.060 23.3

0.070 17.9

0.081 17.1

0.093 14.6

0.11 14.0

0.12 12.9

0.14 12.6

0.17 14.8

0.19 11.3

0.22 13.5

0.26 11.0

0.29 15.9

0.30 – 0.40 20.6

0.40 – 0.55 25.5

0.55 – 0.70 24.6

0.70 – 1.00 32.2

1.00 – 1.30 37.3

1.30 – 1.60 38.8

1.60 – 2.20 41.8

2.20 – 3.00 57.1

3.00 – 4.00 67.9

4.00 – 5.50 75.4

5.50 – 7.00 83.7

7.00 – 10.00 88.4

E1 (0.30 – 1.0) 25.7

E2 (1.0 – 3.0) 43.7

E3 (3.0 – 10.0) 78.9

MERV rating from vendor 11

MERV rating from testing 8
E-13

Table E-13. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 12"

Pleated Non-Electrostatic Filter (C5PSC-11)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm)

Air Velocity 

(fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 77.1 984 246 0.25 NA

0.034 74.0 1476 369 0.43 NA

0.039 69.4 1968 492 0.64 0.60 @ 500 fpm

0.045 66.9 2460 615 0.90 NA

0.052 62.7

0.060 59.3

0.070 55.4

0.081 52.9

0.093 50.7

0.11 49.8

0.12 48.5

0.14 48.5

0.17 48.7

0.19 50.2

0.22 51.9

0.26 51.1

0.29 51.2

0.30 – 0.40 49.0

0.40 – 0.55 56.5

0.55 – 0.70 62.8

0.70 – 1.00 71.0

1.00 – 1.30 75.5

1.30 – 1.60 80.4

1.60 – 2.20 85.9

2.20 – 3.00 92.4

3.00 – 4.00 95.0

4.00 – 5.50 97.0

5.50 – 7.00 98.0

7.00 – 10.00 99.0

E1 (0.30 – 1.0) 59.8

E2 (1.0 – 3.0) 83.6

E3 (3.0 – 10.0) 97.2

MERV rating from vendor 13

MERV rating from testing 12
E-14

Table E-14. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 10"

6-Pocket Non-Electrostatic Bag Filter (C6ADP-15)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm)

Air Velocity 

(fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s Pressure 

Drop Data (in. w.g.) 

(based on 24" x 24" 

x 30" filter with 8 

pockets)

0.029 75.9 984 246 0.77 0.68 @ 250 fpm

0.034 75.1 1476 369 1.21 1.10 @ 375 fpm

0.039 73.9 1968 492 1.68 1.48 @ 500 fpm

0.045 72.7 2460 615 2.18 1.76 @ 560 fpm

0.052 70.8

0.060 68.9

0.070 66.6

0.081 65.1

0.093 63.1

0.11 61.8

0.12 61.9

0.14 61.0

0.17 60.0

0.19 60.2

0.22 61.9

0.26 63.4

0.29 62.1

0.30 – 0.40 68.0

0.40 – 0.55 80.0

0.55 – 0.70 86.5

0.70 – 1.00 93.9

1.00 – 1.30 96.6

1.30 – 1.60 97.7

1.60 – 2.20 98.6

2.20 – 3.00 99.3

3.00 – 4.00 99.4

4.00 – 5.50 99.2

5.50 – 7.00 99.5

7.00 – 10.00 99.5

E1 (0.30 – 1.0) 82.1

E2 (1.0 – 3.0) 98.1

E3 (3.0 – 10.0) 99.4

MERV rating from vendor 14

MERV rating from testing 14
E-15

Table E-15. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 12"

Pleated Electrostatic Box Filter (C7CFER-13)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 86.5 984 246 0.38 0.22 @ 250 fpm

0.034 83.7 1476 369 0.60 0.38 @ 375 fpm

0.039 80.0 1968 492 0.85 0.58 @ 500 fpm

0.045 77.6 2460 615 1.12 0.80 @ 625 fpm

0.052 75.2

0.060 71.8

0.070 68.5

0.081 66.6

0.093 65.0

0.11 63.7

0.12 62.8

0.14 62.9

0.17 63.1

0.19 63.4

0.22 64.9

0.26 65.9

0.29 67.7

0.30 – 0.40 69.7

0.40 – 0.55 79.2

0.55 – 0.70 84.3

0.70 – 1.00 91.0

1.00 – 1.30 94.1

1.30 – 1.60 95.9

1.60 – 2.20 97.7

2.20 – 3.00 99.3

3.00 – 4.00 99.7

4.00 – 5.50 99.7

5.50 – 7.00 99.8

7.00 – 10.00 99.8

E1 (0.30 – 1.0) 81.1

E2 (1.0 – 3.0) 96.8

E3 (3.0 – 10.0) 99.8

MERV rating from vendor 14

MERV rating from testing 14
E-16

Table E-16. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 12"

Pleated Electrostatic Box Filter (C8GZ-13) (Test #1)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 74.8 984 246 0.25 NA

0.034 73.0 1476 369 0.40 NA

0.039 72.9 1968 492 0.59 0.44 @ 500 fpm

0.045 73.2 2460 615 0.80 NA

0.052 72.2

0.060 70.8

0.070 69.6

0.081 68.2

0.093 68.8

0.11 66.1

0.12 65.4

0.14 65.4

0.17 64.7

0.19 63.7

0.22 63.2

0.26 63.2

0.29 60.3

0.30 – 0.40 60.9

0.40 – 0.55 66.4

0.55 – 0.70 72.5

0.70 – 1.00 77.7

1.00 – 1.30 82.3

1.30 – 1.60 85.5

1.60 – 2.20 90.1

2.20 – 3.00 95.2

3.00 – 4.00 97.3

4.00 – 5.50 98.5

5.50 – 7.00 99.2

7.00 – 10.00 99.6

E1 (0.30 – 1.0) 69.4

E2 (1.0 – 3.0) 88.3

E3 (3.0 – 10.0) 98.6

MERV rating from vendor 13

MERV rating from testing 12
E-17

Table E-17. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 12"

Pleated Electrostatic Box Filter (C8GZ-13) (Test #2)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 65.5 984 246 0.26 NA

0.034 64.7 1476 369 0.43 NA

0.039 60.1 1968 492 0.63 0.44 @ 500 fpm

0.045 61.5 2460 615 0.89 NA

0.052 58.3

0.060 59.4

0.070 58.8

0.081 55.4

0.093 56.3

0.11 53.6

0.12 53.8

0.14 52.0

0.17 52.5

0.19 53.7

0.22 50.4

0.26 53.4

0.29 53.9

0.30 – 0.40 66.3

0.40 – 0.55 73.8

0.55 – 0.70 81.7

0.70 – 1.00 88.3

1.00 – 1.30 94.0

1.30 – 1.60 96.1

1.60 – 2.20 97.2

2.20 – 3.00 97.9

3.00 – 4.00 98.2

4.00 – 5.50 98.4

5.50 – 7.00 98.2

7.00 – 10.00 100.0

E1 (0.30 – 1.0) 77.5

E2 (1.0 – 3.0) 96.3

E3 (3.0 – 10.0) 98.7

MERV rating from vendor 13

MERV rating from testing 14
E-18

Table E-18. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24"x 12" 

Pleated Non-Electrostatic Filter (C14PCS)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 85.4 984 246 0.24 0.25 @ 250 fpm

0.034 83.6 1476 369 0.41 0.40 @ 375 fpm

0.039 80.3 1968 492 0.60 0.60 @ 500 fpm

0.045 77.1 2460 615 0.83 0.78 @ 625 fpm

0.052 73.7

0.060 71.5

0.070 67.5

0.081 65.3

0.093 63.6

0.11 61.1

0.12 60.6

0.14 61.7

0.17 61.6

0.19 60.0

0.22 63.8

0.26 64.3

0.29 66.6

0.30 – 0.40 62.0

0.40 – 0.55 68.6

0.55 – 0.70 74.4

0.70 – 1.00 80.2

1.00 – 1.30 84.0

1.30 – 1.60 86.7

1.60 – 2.20 91.3

2.20 – 3.00 95.7

3.00 – 4.00 97.6

4.00 – 5.50 98.6

5.50 – 7.00 99.1

7.00 – 10.00 99.3

E1 (0.30 – 1.0) 71.3

E2 (1.0 – 3.0) 89.4

E3 (3.0 – 10.0) 98.6

MERV rating from vendor 14

MERV rating from testing 12
E-19

Table E-19. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 15"

8-Pocket Electrostatic Bag Filter (C10CFS-14)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm)

Air Velocity 

(fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop Data 

for a 12 pocket filter 

(in. w.g.)

0.029 73.0 984 246 0.25 0.21 @ 250 fpm

0.034 71.8 1476 369 0.40 0.35 @ 375 fpm

0.039 71.6 1968 492 0.57 0.50 @ 500 fpm

0.045 69.9 2460 615 0.74 NA

0.052 69.9

0.060 68.8

0.070 69.2

0.081 66.8

0.093 66.9

0.11 65.0

0.12 63.8

0.14 62.9

0.17 62.0

0.19 62.5

0.22 63.5

0.26 64.9

0.29 65.4

0.30 – 0.40 72.2

0.40 – 0.55 79.3

0.55 – 0.70 83.3

0.70 – 1.00 89.1

1.00 – 1.30 92.1

1.30 – 1.60 93.9

1.60 – 2.20 96.1

2.20 – 3.00 98.1

3.00 – 4.00 98.7

4.00 – 5.50 98.9

5.50 – 7.00 99.0

7.00 – 10.00 99.1

E1 (0.30 – 1.0) 81.0

E2 (1.0 – 3.0) 95.0

E3 (3.0 – 10.0) 98.9

MERV rating from vendor 14

MERV rating from testing 14
E-20

Table E-20. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 12"

Pleated Non-Electrostatic Filter (C11GM-16)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm)

Air Velocity 

(fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 99.9 984 246 0.37 0.42 @ 250 fpm

0.034 99.8 1476 369 0.59 0.55 @ 375 fpm

0.039 99.7 1968 492 0.85 0.61 @ 500 fpm

0.045 99.4 2460 615 1.14 NA

0.052 99.0

0.060 98.4

0.070 97.7

0.081 96.9

0.093 96.2

0.11 95.6

0.12 95.0

0.14 94.9

0.17 94.9

0.19 95.2

0.22 94.9

0.26 95.1

0.29 96.3

0.30 – 0.40 97.0

0.40 – 0.55 98.4

0.55 – 0.70 99.2

0.70 – 1.00 99.6

1.00 – 1.30 99.8

1.30 – 1.60 99.9

1.60 – 2.20 99.9

2.20 – 3.00 100.0

3.00 – 4.00 100.0

4.00 – 5.50 100.0

5.50 – 7.00 100.0

7.00 – 10.00 100.0

E1 (0.30 – 1.0) 98.6

E2 (1.0 – 3.0) 99.9

E3 (3.0 – 10.0) 100

MERV rating from vendor 16

MERV rating from testing 16
E-21

Table E-21. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 12"

Pleated Non-Electrostatic Filter (C12AB-16)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm)

Air Velocity 

(fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 99.0 984 246 0.44 0.40 @ 250 fpm

0.034 98.9 1476 369 0.71 NA

0.039 98.4 1968 492 1.01 0.95 @ 500 fpm

0.045 97.7 2460 615 1.35 NA

0.052 96.8

0.060 96.1

0.070 94.8

0.081 93.9

0.093 93.3

0.11 92.8

0.12 92.4

0.14 92.5

0.17 92.5

0.19 93.0

0.22 94.0

0.26 93.8

0.29 94.6

0.30 – 0.40 96.1

0.40 – 0.55 97.7

0.55 – 0.70 98.7

0.70 – 1.00 99.3

1.00 – 1.30 99.4

1.30 – 1.60 99.6

1.60 – 2.20 99.8

2.20 – 3.00 99.8

3.00 – 4.00 99.8

4.00 – 5.50 100.0

5.50 – 7.00 100.0

7.00 – 10.00 100.0

E1 (0.30 – 1.0) 98.0

E2 (1.0 – 3.0) 99.7

E3 (3.0 – 10.0) 99.9

MERV rating from vendor 16

MERV rating from testing 16
E-22

Table E-22. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 12"

Pleated Non-Electrostatic Filter (C13AMG-16)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 97.1 984 246 0.55 0.40 @ 238 fpm

0.034 97.3 1476 369 0.90 0.65 @ 325 fpm

0.039 97.2 1968 492 1.29 0.95 @ 475 fpm

0.045 97.1 2460 615 1.71 1.35 @ 605 fpm

0.052 96.9

0.060 96.5

0.070 96.4

0.081 96.2

0.093 96.0

0.11 96.0

0.12 96.0

0.14 96.1

0.17 96.3

0.19 96.5

0.22 96.8

0.26 96.5

0.29 96.8

0.30 – 0.40 95.5

0.40 – 0.55 96.6

0.55 – 0.70 96.4

0.70 – 1.00 96.9

1.00 – 1.30 97.0

1.30 – 1.60 96.5

1.60 – 2.20 96.3

2.20 – 3.00 97.2

3.00 – 4.00 97.0

4.00 – 5.50 97.2

5.50 – 7.00 97.9

7.00 – 10.00 98.0

E1 (0.30 – 1.0) 96.4

E2 (1.0 – 3.0) 96.8

E3 (3.0 – 10.0) 97.5

MERV rating from vendor 16

MERV rating from testing 16
E-23

Table E-23. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 12"

Pleated Non-Electrostatic HEPA Filter (C114FA-H)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 99.3 984 246 0.62 NA

0.034 99.3 1476 369 0.97 0.90 @ 344 fpm

0.039 99.3 1968 492 1.34 1.45 @ 500 fpm

0.045 99.3 2460 615 1.74 1.90 @ 640 fpm

0.052 99.3

0.060 99.4

0.070 99.4

0.081 99.4

0.093 99.3

0.11 99.3

0.12 99.3

0.14 99.4

0.17 99.4

0.19 99.4

0.22 99.4

0.26 99.5

0.29 99.5

0.30 – 0.40 100.0

0.40 – 0.55 100.0

0.55 – 0.70 100.0

0.70 – 1.00 100.0

1.00 – 1.30 100.0

1.30 – 1.60 100.0

1.60 – 2.20 100.0

2.20 – 3.00 100.0

3.00 – 4.00 100.0

4.00 – 5.50 100.0

5.50 – 7.00 100.0

7.00 – 10.00 100.0

E1 (0.30 – 1.0) 100

E2 (1.0 – 3.0) 100

E3 (3.0 – 10.0) 100

MERV rating from vendor 16+

MERV rating from testing 16+
E-24

Table E-24. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 2"

Pleated Electrostatic Filter (C15AAA-11)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 45.1 984 246 0.13 0.12 @ 250 fpm

0.034 50.7 1476 369 0.22 0.23 @ 375 fpm

0.039 48.1 1968 492 0.34 0.38 @ 500 fpm

0.045 44.1 2460 615 0.47 0.51 @ 625 fpm

0.052 42.1

0.060 39.5

0.070 34.4

0.081 32.1

0.093 29.3

0.11 29.1

0.12 26.1

0.14 25.1

0.17 21.8

0.19 22.9

0.22 22.2

0.26 16.1

0.29 17.3

0.30 – 0.40 29.0

0.40 – 0.55 35.6

0.55 – 0.70 47.1

0.70 – 1.00 52.6

1.00 – 1.30 66.4

1.30 – 1.60 71.4

1.60 – 2.20 76.5

2.20 – 3.00 73.4

3.00 – 4.00 71.3

4.00 – 5.50 70.9

5.50 – 7.00 65.4

7.00 – 10.00 58.9

E1 (0.30 – 1.0) 41.1

E2 (1.0 – 3.0) 71.9

E3 (3.0 – 10.0) 66.6

MERV rating from vendor 11

MERV rating from testing 7
E-25

Table E-25. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 12" x 24" x 2"

Pleated Electrostatic Filter (C15AAA-11)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 36.2 492 246 0.14 0.12 @ 250 fpm

0.034 35.2 738 369 0.25 0.23 @ 375 fpm

0.039 35.4 984 492 0.40 0.38 @ 500 fpm

0.045 36.3 1230 615 0.59 0.51 @ 625 fpm

0.052 32.9

0.060 30.7

0.070 31.0

0.081 29.7

0.093 27.0

0.11 26.2

0.12 25.1

0.14 23.9

0.17 20.8

0.19 22.1

0.22 22.4

0.26 22.4

0.29 20.9

0.30 – 0.40 39.6

0.40 – 0.55 40.5

0.55 – 0.70 50.6

0.70 – 1.00 59.1

1.00 – 1.30 67.6

1.30 – 1.60 73.0

1.60 – 2.20 75.2

2.20 – 3.00 75.9

3.00 – 4.00 74.7

4.00 – 5.50 71.5

5.50 – 7.00 73.0

7.00 – 10.00 66.5

E1 (0.30 – 1.0) 47.5

E2 (1.0 – 3.0) 72.9

E3 (3.0 – 10.0) 71.4

MERV rating from vendor 11

MERV rating from testing 8
E-26

Table E-26. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 24" x 24" x 2"

Pleated Electrostatic Filter (C17FPP-8)

Particle Size Range 

or Midpoint of Range 

(μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop (in. 

w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 29.7 984 246 0.17 0.10 @ 250 fpm

0.034 34.8 1476 369 0.29 0.18 @ 375 fpm

0.039 30.1 1968 492 0.44 0.30 @ 500 fpm

0.045 28.0 2460 615 0.63 0.45 @ 625 fpm

0.052 22.0

0.060 20.9

0.070 17.5

0.081 18.4

0.093 14.4

0.11 12.7

0.12 11.9

0.14 15.3

0.17 12.0

0.19 13.5

0.22 8.1

0.26 15.0

0.29 16.4

0.30 – 0.40 34.5

0.40 – 0.55 39.9

0.55 – 0.70 52.3

0.70 – 1.00 66.7

1.00 – 1.30 86.7

1.30 – 1.60 90.6

1.60 – 2.20 93.3

2.20 – 3.00 93.8

3.00 – 4.00 92.2

4.00 – 5.50 89.0

5.50 – 7.00 62.7

7.00 – 10.00 NA <500 particles

E1 (0.30 – 1.0) 48.3

E2 (1.0 – 3.0) 91.1

E3 (3.0 – 10.0) 81.3

MERV rating from vendor 11

MERV rating from testing 8
E-27

Table E-27. Initial Measured Collection Efficiency and Pressure Drop of a Commercial 12" x 24" x 2"

Pleated Electrostatic Filter (C17FPP-8)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 40.8 492 246 0.20 0.10 @ 250 fpm

0.034 36.7 738 369 0.35 0.18 @ 375 fpm

0.039 33.6 984 492 0.55 0.30 @ 500 fpm

0.045 30.4 1230 615 0.75 0.45 @ 625 fpm

0.052 26.2

0.060 22.1

0.070 20.8

0.081 18.3

0.093 17.1

0.11 17.9

0.12 15.9

0.14 14.2

0.17 11.5

0.19 13.9

0.22 16.8

0.26 17.3

0.29 15.5

0.30 – 0.40 30.2

0.40 – 0.55 29.6

0.55 – 0.70 41.4

0.70 – 1.00 55.0

1.00 – 1.30 69.4

1.30 – 1.60 76.0

1.60 – 2.20 79.2

2.20 – 3.00 77.4

3.00 – 4.00 73.2

4.00 – 5.50 66.2

5.50 – 7.00 63.8

7.00 – 10.00 55.7

E1 (0.30 – 1.0) 39.1

E2 (1.0 – 3.0) 75.5

E3 (3.0 – 10.0) 64.7

MERV rating from vendor 11

MERV rating from testing 7
E-28

Table E-28. Initial Measured Collection Efficiency and Pressure Drop of a Residential 16" x 25"

Electronic Air Cleaner (Unit A – used for ambient aging)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 93.1 410 148 0.05 NA

0.034 92.5 614 221 0.08 NA

0.039 92.3 819 295 0.12 0.10 @ 360 fpm

0.045 91.6 1024 369 0.17 0.14 @ 432 fpm

0.052 91.0 0.17 @ 504 fpm

0.060 90.5 0.29 @ 720 fpm

0.070 89.7

0.081 89.0

0.093 88.3

0.11 88.1

0.12 87.3

0.14 86.8

0.17 85.6

0.19 85.0

0.22 84.2

0.26 84.7

0.29 83.5

0.30 – 0.40 80.8

0.40 – 0.55 82.8

0.55 – 0.70 85.4

0.70 – 1.00 87.7

1.00 – 1.30 90.6

1.30 – 1.60 91.9

1.60 – 2.20 94.1

2.20 – 3.00 95.6

3.00 – 4.00 96.7

4.00 – 5.50 97.8

5.50 – 7.00 98.0

7.00 – 10.00 99.2

E1 (0.30 – 1.0) 84.2

E2 (1.0 – 3.0) 93.1

E3 (3.0 – 10.0) 97.9

MERV rating from vendor 15

MERV rating from testing 14
E-29

Table E-29. Initial Measured Collection Efficiency and Pressure Drop of a Residential 16" x 25"

Electronic Air Cleaner (Unit A – used for silicon vapor tests)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 95.1 410 148 0.05 NA

0.034 95.1 614 221 0.07 NA

0.039 95.4 819 295 0.11 0.10 @ 360 fpm

0.045 95.2 1024 369 0.15 0.14 @ 432 fpm

0.052 94.9 0.17 @ 504 fpm

0.060 94.6 0.29 @ 720 fpm

0.070 94.6

0.081 94.2

0.093 94.3

0.11 94.2

0.12 93.9

0.14 93.7

0.17 93.3

0.19 93.1

0.22 92.8

0.26 93.7

0.29 93.3

0.30 – 0.40 89.3

0.40 – 0.55 90.3

0.55 – 0.70 91.4

0.70 – 1.00 92.2

1.00 – 1.30 93.4

1.30 – 1.60 94.0

1.60 – 2.20 94.8

2.20 – 3.00 95.4

3.00 – 4.00 96.1

4.00 – 5.50 96.9

5.50 – 7.00 97.0

7.00 – 10.00 96.3

E1 (0.30 – 1.0) 90.8

E2 (1.0 – 3.0) 94.4

E3 (3.0 – 10.0) 96.6

MERV rating from vendor 15

MERV rating from testing 15
E-30

Table E-30. Initial Measured Collection Efficiency and Pressure Drop of a Residential 20" x 20"

Electronic Air Cleaner (Unit H – used for ambient aging)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 93.8 410 148 0.03 0.03 @ 148 fpm

0.034 94.5 614 221 0.06 0.04 @ 221 fpm

0.039 94.8 819 295 0.11 0.06 @ 295 fpm

0.045 94.4 1024 369 0.17 0.09 @ 369 fpm

0.052 93.6

0.060 92.8

0.070 91.9

0.081 91.4

0.093 90.2

0.11 89.4

0.12 88.8

0.14 88.5

0.17 87.2

0.19 88.5

0.22 87.8

0.26 87.5

0.29 87.1

0.30 – 0.40 89.3

0.40 – 0.55 91.9

0.55 – 0.70 94.0

0.70 – 1.00 95.5

1.00 – 1.30 96.5

1.30 – 1.60 96.6

1.60 – 2.20 97.1

2.20 – 3.00 97.4

3.00 – 4.00 97.6

4.00 – 5.50 98.0

5.50 – 7.00 98.0

7.00 – 10.00 98.8

E1 (0.30 – 1.0) 92.7

E2 (1.0 – 3.0) 96.9

E3 (3.0 – 10.0) 98.1

MERV rating from vendor Up to 12

MERV rating from testing 15
E-31

Table E-31. Initial Measured Collection Efficiency and Pressure Drop of a Residential 20" x 20"

Electronic Air Cleaner (Unit H – used for silicon vapor tests)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 92.2 410 148 0.03 0.03 @ 148 fpm

0.034 94.0 614 221 0.06 0.04 @ 221 fpm

0.039 94.2 819 295 0.11 0.06 @ 295 fpm

0.045 93.8 1024 369 0.17 0.09 @ 369 fpm

0.052 93.4

0.060 92.5

0.070 91.5

0.081 90.5

0.093 89.4

0.11 88.3

0.12 87.7

0.14 86.6

0.17 86.9

0.19 87.0

0.22 87.1

0.26 87.3

0.29 87.9

0.30 – 0.40 86.8

0.40 – 0.55 90.5

0.55 – 0.70 93.3

0.70 – 1.00 95.2

1.00 – 1.30 96.5

1.30 – 1.60 97.1

1.60 – 2.20 97.4

2.20 – 3.00 97.7

3.00 – 4.00 98.3

4.00 – 5.50 98.5

5.50 – 7.00 98.9

7.00 – 10.00 99.5

E1 (0.30 – 1.0) 91.5

E2 (1.0 – 3.0) 97.2

E3 (3.0 – 10.0) 98.8

MERV rating from vendor Up to 12

MERV rating from testing 15
E-32

Table E-32. Initial Measured Collection Efficiency and Pressure Drop of a Residential 20" x 20" 

Electronic Air Cleaner (Unit P – used for ambient aging)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm) Air Velocity (fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 81.2 410 148 0.02 NA

0.034 84.4 614 221 0.04 NA

0.039 88.2 819 295 0.06 NA

0.045 88.5 1024 369 0.09 0.11 @ 504 fpm

0.052 87.9

0.060 86.7

0.070 85.5

0.081 83.7

0.093 81.7

0.11 80.9

0.12 80.1

0.14 78.5

0.17 79.0

0.19 77.5

0.22 80.0

0.26 79.7

0.29 80.8

0.30 – 0.40 76.7

0.40 – 0.55 82.1

0.55 – 0.70 86.5

0.70 – 1.00 90.5

1.00 – 1.30 93.6

1.30 – 1.60 94.9

1.60 – 2.20 95.7

2.20 – 3.00 96.2

3.00 – 4.00 96.6

4.00 – 5.50 97.0

5.50 – 7.00 97.6

7.00 – 10.00 97.1

E1 (0.30 – 1.0) 84.0

E2 (1.0 – 3.0) 95.1

E3 (3.0 – 10.0) 97.1

MERV rating from vendor NA

MERV rating from testing 14
E-33

Table E-33. Initial Measured Collection Efficiency and Pressure Drop of a Residential 20" x 20"

Electronic Air Cleaner (Unit P – used for silicon vapor tests)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size 

Efficiency (%)

Airflow Rate 

(cfm)

Air Velocity 

(fpm)

Measured 

Pressure Drop 

(in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

0.029 86.4 410 148 0.03 NA

0.034 88.2 614 221 0.05 NA

0.039 89.1 819 295 0.08 NA

0.045 88.8 1024 369 0.13 0.11 @ 504 fpm

0.052 87.3

0.060 86.1

0.070 84.1

0.081 83.1

0.093 80.6

0.11 80.0

0.12 78.4

0.14 76.9

0.17 74.5

0.19 74.3

0.22 73.9

0.26 72.9

0.29 72.5

0.30 – 0.40 73.9

0.40 – 0.55 80.3

0.55 – 0.70 85.7

0.70 – 1.00 90.0

1.00 – 1.30 93.7

1.30 – 1.60 95.0

1.60 – 2.20 96.0

2.20 – 3.00 96.8

3.00 – 4.00 96.9

4.00 – 5.50 97.4

5.50 – 7.00 97.0

7.00 – 10.00 96.4

E1 (0.30 – 1.0) 82.5

E2 (1.0 – 3.0) 95.3

E3 (3.0 – 10.0) 96.9

MERV rating from vendor NA

MERV rating from testing 14
E-34

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F-1

Appendix F

Results from the Bioaerosol Evaluations

of “Off-the-Shelf” Air Cleaners

Table F-1. Results from Bioaerosol Evaluation of Residential Filter 2NS-8-1

Sample

Airflow 

Velocity 

(fpm)

Average 

Airflow 

Velocity 

(fpm)

Airflow 

Velocity 

Standard 

Deviation 

(fpm)

Airflow 

Velocity 

Coefficient 

of Variance 

(%)

CFU/liter 

of air

Average 

Concentration 

(CFU/liter of air) Std. Dev.

Coefficient of 

Variance

Upstream 203

208

(832 cfm)

37.6 18.1 4.99*103

4.87*103

6.97*102 14%

Upstream 253 3.52*103

Upstream 189 4.30*103

Upstream 221 6.00*103

Upstream 267 5.27*103

Upstream 224 5.28*103

Upstream 175 5.07*103

Upstream 206 4.82*103

Upstream 135 4.56*103

Downstream - - - - 3.66*103 4.15*103 6.50*102 16%

Downstream - - - - 4.14*103

Downstream - - - - 4.37*103

Downstream - - - - 3.34*103

Downstream - - - - 3.96*103

Downstream - - - - 5.06*103

Downstream - - - - 4.91*103

Downstream - - - - 3.28*103

Downstream - - - - 4.63*103

Background - - - - <2.7

Background - - - - <2.8

Pressure Drop 

(in. w.g.)

0.20

Pmeasured 0.853

P100 0.995

Pcorrected 0.857

Filtration 

Efficiency

14%

Combined 

Standard 

Deviation

18%
F-2

Table F-2. Results from Bioaerosol Evaluation of Residential Filter 4FUA-12-1

Sample

Airflow 

Velocity 

(fpm)

Average 

Airflow 

Velocity 

(fpm)

Airflow 

Velocity 

Standard 

Deviation 

(fpm)

Airflow 

Velocity 

Coefficient of 

Variance (%)

CFU/liter of 

air

Average 

Concentration 

(CFU/liter of air) Std. Dev.

Coefficient of 

Variance

Upstream 220

207 (828 cfm)

43.2 20.8 5.93*103

5.28*103

5.05*102 10%

Upstream 274 5.25*103

Upstream 188 4.22*103

Upstream 197 5.58*103

Upstream 262 3.89*102A

Upstream 210 5.48*103

Upstream 165 5.47*103

Upstream 224 5.29*103

Upstream 126 5.03*103

Downstream - - - - 3.06*103 2.61*103 7.15*102 27%

Downstream - - - - 2.90*103

Downstream - - - - 2.99*103

Downstream - - - - 3.47*103

Downstream - - - - 1.63*103

Downstream - - - - 2.24*102A

Downstream - - - - 2.32*103

Downstream - - - - 2.97*103

Downstream - - - - 1.50*103

Background - - - - <2.7

Background - - - - <2.8

Pressure Drop 

(in. w.g.)

0.15

Pmeasured 0.493

P100 0.995

Pcorrected 0.496

Filtration 

Efficiency

50%

Combined 

Standard 

Deviation

14%

A – Excluded from calculations due to difference of an order of magnitude from the average.
F-3

Table F-3. Results from Bioaerosol Evaluation of Residential Filter 8NM-10-1

Sample

Airflow 

Velocity 

(fpm)

Average 

Airflow 

Velocity (fpm)

Airflow 

Velocity 

Standard 

Deviation 

(fpm)

Airflow 

Velocity 

Coefficient of 

Variance (%)

CFU/liter of 

air

Average 

Concentration 

(CFU/liter of air) Std. Dev.

Coefficient of 

Variance

Upstream 165

209 (836 cfm)

53.2 25.4 5.38*103

4.91*103

4.40*102 9%

Upstream 280 4.59*103

Upstream 186 5.75*103

Upstream 153 5.01*103

Upstream 299 4.61*103

Upstream 225 4.78*103

Upstream 167 4.83*103

Upstream 252 4.28*103

Upstream 156 4.92*103

Downstream - - - - 2.97*103 2.93*103 1.68*102 6%

Downstream - - - - 2.88*103

Downstream - - - - 2.82*103

Downstream - - - - 2.62*103

Downstream - - - - 2.92*103

Downstream - - - - 2.93*103

Downstream - - - - 2.90*103

Downstream - - - - 3.21*103

Downstream - - - - 3.12*103

Background - - - - <2.7

Background - - - - <2.8

Pressure Drop 

(in. w.g.)

0.15

Pmeasured 0.597

P100 0.995

Pcorrected 0.600

Filtration 

Efficiency

40%

Combined 

Standard 

Deviation

6%
F-4

Table F-4. Results from Bioaerosol Evaluation of Residential Filter 6DDUE-8-12

Sample

Airflow 

Velocity 

(fpm)

Average Airflow 

Velocity (fpm)

Airflow 

Velocity 

Standard 

Deviation 

(fpm)

Airflow 

Velocity 

Coefficient 

of Variance 

(%)

CFU/liter 

of air

Average 

Concentration 

(CFU/liter of air) Std. Dev.

Coefficient of 

Variance

Upstream 184

211 (844 cfm)

44.2 21.0 5.41*103

4.45*103

5.98*102 13%

Upstream 257 4.58*103

Upstream 191 4.31*103

Upstream 231 5.42*103

Upstream 288 4.12*103

Upstream 203 4.42*103

Upstream 178 3.82*103

Upstream 232 4.09*103

Upstream 131 3.86*103

Downstream - - - - 4.46*103 4.15*103 6.48*102 16%

Downstream - - - - 4.09*103

Downstream - - - - 3.20*103

Downstream - - - - 5.34*103

Downstream - - - - 4.75*103

Downstream - - - - 3.46*103

Downstream - - - - 4.07*103

Downstream - - - - 3.85*103

Downstream - - - - 4.11*103

Background - - - - <2.7

Background - - - - <2.8

Pressure Drop 

(in. w.g.)

0.13

Pmeasured 0.932

P100 0.995

Pcorrected 0.937

Filtration 

Efficiency

6%

Combined 

Standard 

Deviation

19%
F-5

Table F-5. Results from Bioaerosol Evaluation of Electronic Air Cleaner Unit A

Sample

Airflow 

Velocity 

(fpm)

Average 

Airflow 

Velocity (fpm)

Airflow 

Velocity 

Standard 

Deviation 

(fpm)

Airflow 

Velocity 

Coefficient of 

Variance (%)

CFU/liter of 

air

Average 

Concentration 

(CFU/liter of 

air) Std. Dev.

Coefficient of 

Variance

Upstream 173

200 (800 cfm)

35.6 17.8 7.21*103

4.56*103

1.26*103 28%

Upstream 247 4.16*103

Upstream 177 3.51*103

Upstream 173 4.78*103

Upstream 266 4.55*103

Upstream 206 3.60*103

Upstream 167 5.77*103

Upstream 222 4.31*103

Upstream 165 3.17*103

Downstream - - - - 1.94*102 3.19*102 3.66*102 115%

Downstream - - - - 2.42*101

Downstream - - - - 5.40*100

Downstream - - - - 1.07*103

Downstream - - - - 7.36*102

Downstream - - - - 3.88*102

Downstream - - - - 3.19*102

Downstream - - - - 4.34*101

Downstream - - - - 8.69*101

Background - - - - <2.7

Background - - - - <2.8

Pressure Drop 

(in. w.g.)

0.06

Pmeasured 0.069

P100 0.995

Pcorrected 0.070

Filtration 

Efficiency

93%

Combined 

Standard 

Deviation

8%
F-6

Table F-6. Results from Bioaerosol Evaluation of Electronic Air Cleaner Unit H

Sample

Airflow 

Velocity 

(fpm)

Average 

Airflow 

Velocity (fpm)

Airflow 

Velocity 

Standard 

Deviation 

(fpm)

Airflow 

Velocity 

Coefficient 

of Variance 

(%)

CFU/liter 

of air

Average 

Concentration 

(CFU/liter of air) Std. Dev.

Coefficient of 

Variance

Upstream 209

210 (840 cfm)

44.7 21.2 5.74*103 4.10*103 8.74*102 21%

Upstream 275 4.44*103

Upstream 223 3.75*103

Upstream 210 4.80*103

Upstream 274 3.87*103

Upstream 208 3.72*103

Upstream 158 2.58*103

Upstream 206 4.28*103

Upstream 128 3.70*103

Downstream - - - - 5.85*102 4.38*102 2.50*102 57%

Downstream - - - - 1.43*102

Downstream - - - - 7.91*102

Downstream - - - - 2.62*102

Downstream - - - - 6.48*101

Downstream - - - - 4.96*102

Downstream - - - - 6.82*102

Downstream - - - - 3.28*102

Downstream - - - - 5.89*102

Background - - - - <2.7

Background - - - - <2.8

Pressure Drop 

(in. w.g.)

0.05

Pmeasured 0.107

P100 0.995

Pcorrected 0.107

Filtration 

Efficiency

89%

Combined 

Standard 

Deviation

7%
F-7

Table F-7. Results from Bioaerosol Evaluation of Electronic Air Cleaner Unit P

Sample

Airflow 

Velocity 

(fpm)

Average 

Airflow 

Velocity (fpm)

Airflow 

Velocity 

Standard 

Deviation 

(fpm)

Airflow 

Velocity 

Coefficient 

of Variance 

(%)

CFU/liter 

of air

Average 

Concentration 

(CFU/liter of air) Std. Dev.

Coefficient of 

Variance

Upstream 190

201 (804 cfm)

37.5 18.6 6.22*103

4.74*103

8.53*102 18%

Upstream 258 4.49*103

Upstream 187 3.42*103

Upstream 202 5.78*103

Upstream 260 4.72*103

Upstream 208 4.57*103

Upstream 162 5.02*103

Upstream 207 4.45*103

Upstream 138 4.01*103

Downstream - - - - 4.36*102 2.58*102 1.76*102 68%

Downstream - - - - 3.58*101

Downstream - - - - 3.15*102

Downstream - - - - 3.87*102

Downstream - - - - 5.33*101

Downstream - - - - 3.65*102

Downstream - - - - 4.82*102

Downstream - - - - 6.47*101

Downstream - - - - 1.85*102

Background - - - - <2.7

Background - - - - <2.8

Pressure Drop 

(in. w.g.)

0.03

Pmeasured 0.054

P100 0.995

Pcorrected 0.054

Filtration 

Efficiency

95%

Combined 

Standard 

Deviation

4%
F-8

Table F-8. Results from Bioaerosol Evaluation of Filter C15AAA-11-BIO (12" x 24" x 2")

Sample

Airflow 

Velocity 

(fpm)

Average 

Airflow 

Velocity (fpm)

Airflow 

Velocity 

Standard 

Deviation 

(fpm)

Airflow 

Velocity 

Coefficient 

of Variance 

(%) CFU/liter of air

Average 

Concentration 

(CFU/liter

of air) Std. Dev.

Coefficient of 

Variance

Upstream 225

230 (920 cfm)

38.4 16.7 4.94*103

4.50*103

4.79*102 11%

Upstream 263 4.19*103

Upstream 180 4.78*103

Upstream 208 3.85*103

Upstream 296 3.88*103

Upstream 240 4.23*103

Upstream 179 4.80*103

Upstream 269 4.69*103

Upstream 206 5.18*103

Downstream - - - - 1.71*103 1.75*103 6.53*101 4%

Downstream - - - - 1.87*103

Downstream - - - - 1.69*103

Downstream - - - - 1.67*103

Downstream - - - - 1.74*103

Downstream - - - - 1.79*103

Downstream - - - - 1.80*103

Downstream - - - - 1.71*103

Downstream - - - - 1.80*103

Background - - - - <2.7

Background - - - - <2.8

Pressure Drop 

(in. w.g.)

0.35

Pmeasured 0.389

P100 1.034

Pcorrected 0.376

Filtration 

Efficiency

62%

Combined 

Standard 

Deviation

4%
F-9

Table F-9. Results from Bioaerosol Evaluation of Filter C17FPP-8-BIO (12" x 24" x 2")

Sample

Airflow 

Velocity 

(fpm)

Average Airflow 

Velocity (fpm)

Airflow 

Velocity 

Standard 

Deviation 

(fpm)

Airflow 

Velocity 

Coefficient 

of Variance 

(%)

CFU/liter 

of air

Average 

Concentration 

(CFU/liter of air) Std. Dev.

Coefficient of 

Variance

Upstream 238

254 (1016 cfm)

59.9 23.5 4.66*103 3.90*103 6.01*102 15%

Upstream 356 4.66*103

Upstream 249 4.48*103

Upstream 237 3.06*103

Upstream 344 3.68*103

Upstream 214 3.49*103

Upstream 195 4.19*103

Upstream 287 3.46*103

Upstream 170 3.45*103

Downstream - - - - 2.42*103 2.40*103 2.06*102 9%

Downstream - - - - 2.49*103

Downstream - - - - 2.37*103

Downstream - - - - 2.09*103

Downstream - - - - 2.80*103

Downstream - - - - 2.23*103

Downstream - - - - 2.56*103

Downstream - - - - 2.33*103

Downstream - - - - 2.28*103

Background - - - - <2.7

Background - - - - <2.8

Pressure Drop 

(in. w.g.)

0.45

Pmeasured 0.614

P100 1.034

Pcorrected 0.594

Filtration 

Efficiency

41%

Combined 

Standard 

Deviation

11%
F-10

Table F-10. Results from Bioaerosol Evaluation of Filter C11GM-16-BIO (12" x 24" x 12")

Sample

Airflow 

Velocity 

(fpm)

Average Airflow 

Velocity (fpm)

Airflow 

Velocity 

Standard 

Deviation 

(fpm)

Airflow 

Velocity 

Coefficient of 

Variance (%)

CFU/liter 

of air

Average 

Concentration 

(CFU/liter of air) Std. Dev.

Coefficient 

of Variance

Upstream 258

251 (1004 cfm)

49.0 19.5 3.95*103

4.45*103

5.74*102 13%

Upstream 327 5.05*103

Upstream 253 5.02*103

Upstream 272 3.67*103

Upstream 313 4.36*103

Upstream 214 4.82*103

Upstream 169 3.68*103

Upstream 257 4.44*103

Upstream 193 5.04*103

Downstream - - - - 1.02*101 9.47*100 4.92*100 52%

Downstream - - - - 2.63*100

Downstream - - - - 1.53*101

Downstream - - - - 1.26*101

Downstream - - - - 1.42*101

Downstream - - - - 1.37*101

Downstream - - - - 5.46*100

Downstream - - - - 2.77*100

Downstream - - - - 8.33*100

Background - - - - <2.7

Background - - - - <2.8

Pressure Drop 

(in. w.g.)

0.65

Pmeasured 0.002

P100 1.034

Pcorrected 0.002

Filtration 

Efficiency

99.8%

Combined 

Standard 

Deviation

0.1%
G-1

Appendix G

Results From the Inert Aerosol Evaluations

of the Aged Air Cleaners

Table G-1. Measured Collection Efficiencies During Aging of a Residential 16" x 25" x 1"

Pleated Electrostatic Filter (6DDUE-8)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%)

0 weeks 2 weeks 4 weeks 8 weeks 12 weeks

0.029 25.0 16.8 6.8 13.9 27.9

0.034 33.8 16.6 3.6 16.5 24.5

0.039 30.8 15.7 0.5 2.9 21.3

0.045 28.0 12.8 0.0 2.8 23.1

0.052 27.1 11.2 0.0 1.4 19.9

0.060 25.7 10.5 0.0 0.0 20.3

0.070 23.0 7.7 0.0 1.4 19.9

0.081 22.3 7.3 0.0 0.1 20.5

0.093 22.3 6.6 0.0 0.0 20.6

0.11 23.6 8.8 0.0 0.0 22.1

0.12 23.3 7.3 0.0 0.0 21.7

0.14 23.2 6.4 0.0 0.0 22.0

0.17 21.8 5.2 0.0 0.0 22.9

0.19 25.4 5.6 0.0 0.0 24.0

0.22 25.3 3.8 0.0 0.0 22.5

0.26 18.2 2.5 0.0 7.5 24.7

0.29 18.1 3.8 0.0 8.2 29.1

0.30 – 0.40 16.1 4.7 8.4 0.0 2.3

0.40 – 0.55 14.0 7.1 11.1 1.9 5.7

0.55 – 0.70 21.4 7.5 12.6 5.3 11.8

0.70 – 1.00 31.1 9.8 16.3 10.6 24.0

1.00 – 1.30 44.8 15.2 22.9 19.3 43.2

1.30 – 1.60 50.6 17.4 27.6 27.7 57.2

1.60 – 2.20 55.6 26.1 39.8 40.7 72.7

2.20 – 3.00 56.8 44.6 62.8 54.6 84.9

3.00 – 4.00 57.6 59.5 75.6 64.9 90.4

4.00 – 5.50 55.5 72.7 86.6 69.5 93.6

5.50 – 7.00 59.2 82.6 93.2 69.9 94.6

7.00 – 10.00 54.9 86.2 95.1 64.4 94.3

E1 (0.30 – 1.0) 20.6 7.3 12.1 4.5 11.0

E2 (1.0 – 3.0) 51.9 25.8 38.3 35.6 64.5

E3 (3.0 – 10.0) 56.8 75.3 87.6 67.2 93.2

MERV rating from vendor 8 8 8 8 8

MERV rating from testing 7 8 9 7 10
G-2

Table G-2. Measured Pressure Drops During Aging of a Residential16" x 25" x 1"

Pleated Electrostatic Filter (6DDUE-8)

Weeks of Use 

(hours of operation)

Mass Gained 

(g)

Measured Pressure Drop (in. w.g.)

410 cfm

(148 fpm)

614 cfm

(221 fpm)

819 cfm

(295 fpm)

1,024 cfm

(369 fpm)

0 (0) 0 0.06 0.1 0.14 0.19

2 (199) 1 0.07 0.11 0.16 0.23

4 (544) 8 0.10 0.16 0.23 0.31

8 (1,040) 7 0.09 0.13 0.19 0.26

12 (1,307) 5 0.11 0.17 0.26 0.34

Manufacturer’s Pressure 

Drop Data (in. w.g.) 0.07 @ 148 fpm 0.12 @ 221 fpm 0.17 @ 295 fpm 0.23 @ 369 fpm
G-3

Table G-3. Measured Collection Efficiencies During Aging of a Residential 16" x 25" x 1"

Pleated Electrostatic Filter (8NM-10)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%)

0 weeks 2 weeks 4 weeks 8 weeks 12 weeks

0.029 22.7 30.0 29.9 21.0 31.0

0.034 20.2 26.0 28.7 23.7 29.0

0.039 18.5 25.0 23.2 18.6 27.8

0.045 17.9 23.3 21.5 17.6 25.6

0.052 15.5 20.0 20.1 14.3 23.6

0.060 13.8 18.3 15.9 13.6 22.6

0.070 13.1 18.1 16.8 12.8 19.9

0.081 13.1 17.5 17.0 9.2 22.0

0.093 11.8 20.1 17.2 7.8 22.4

0.11 10.8 18.3 16.0 8.3 23.9

0.12 9.4 18.7 14.9 9.2 26.1

0.14 10.6 16.8 13.9 10.4 27.9

0.17 10.0 17.6 15.2 8.7 31.0

0.19 7.9 19.6 13.8 7.9 33.9

0.22 13.6 21.0 14.2 11.0 36.2

0.26 12.6 21.8 13.6 10.6 43.6

0.29 18.0 17.2 15.8 13.7 47.2

0.30 – 0.40 16.9 6.8 16.5 3.5 48.1

0.40 – 0.55 20.5 16.4 22.8 11.8 59.5

0.55 – 0.70 33.8 21.8 29.3 20.6 72.8

0.70 – 1.00 53.7 33.1 40.4 36.3 82.1

1.00 – 1.30 72.4 42.3 51.3 53.6 88.2

1.30 – 1.60 80.4 50.3 59.1 64.0 90.3

1.60 – 2.20 86.8 63.9 71.0 76.0 92.0

2.20 – 3.00 89.8 80.8 85.0 84.1 93.1

3.00 – 4.00 91.0 87.5 90.4 89.7 93.6

4.00 – 5.50 91.5 91.7 93.6 91.9 94.1

5.50 – 7.00 91.3 94.1 95.3 92.3 93.5

7.00 – 10.00 91.8 94.9 96.0 90.8 92.5

E1 (0.30 – 1.0) 31.2 19.5 27.2 18.1 65.6

E2 (1.0 – 3.0) 82.4 59.3 66.6 69.4 90.9

E3 (3.0 – 10.0) 91.4 92.1 93.8 91.2 93.4

MERV rating from vendor 10 10 10 10 10

MERV rating from testing 12 10 11 11 13
G-4

Table G-4. Measured Pressure Drops During Aging of a Residential 16" x 25" x 1"

Pleated Electrostatic Filter (8NM-10)

Weeks of Use

(hours of operation)

Mass Gained 

(g)

Measured Pressure Drop (in. w.g.)

410 cfm

(148 fpm)

614 cfm

 (221 fpm)

819 cfm

(295 fpm)

1,024 cfm

(369 fpm)

0 (0) 0 0.17 0.29 0.43 0.59

2 (250) 2 0.20 0.34 0.50 0.69

4 (450) 1 0.23 0.39 0.58 0.80

8 (892) 3 0.20 0.33 0.49 0.68

12 (1,272) 9 0.67 1.19 1.75 2.38

Manufacturer’s Pressure 

Drop Data (in. w.g.) NA NA NA NA
G-5

Table G-5. Measured Collection Efficiencies During Aging of a Commercial 24" x 24" x 2"

Pleated Electrostatic Filter (C17FPP-8)

Particle Size Range 

or Midpoint of Range 

(μm)

Particle Size Efficiency (%)

0 weeks

(12 x 24 filter) 0 weeks 2 weeks 4 weeks 8 weeks 16 weeks

0.029 40.8 29.7 22.5 25.5 10.2 21.4

0.034 36.7 34.8 24.2 24.6 11.3 19.0

0.039 33.6 30.1 21.1 21.7 11.4 16.9

0.045 30.4 28.0 18.0 19.7 10.9 11.0

0.052 26.2 22.0 16.2 16.1 10.6 7.5

0.060 22.1 20.9 16.5 14.2 8.9 4.7

0.070 20.8 17.5 15.0 15.0 8.6 5.9

0.081 18.3 18.4 11.5 12.0 7.3 4.5

0.093 17.1 14.4 9.9 9.1 6.5 1.7

0.11 17.9 12.7 10.4 8.8 6.5 1.3

0.12 15.9 11.9 11.6 7.4 7.8 2.4

0.14 14.2 15.3 11.3 5.6 6.9 2.8

0.17 11.5 12.0 8.1 3.4 10.9 1.9

0.19 13.9 13.5 7.5 0.3 10.7 1.4

0.22 16.8 8.1 12.3 3.5 11.0 0.0

0.26 17.3 15.0 9.7 0.0 12.9 1.1

0.29 15.5 16.4 14.2 1.0 15.8 4.5

0.30 – 0.40 30.2 34.0 1.5 1.5 4.7 0.0

0.40 – 0.55 29.6 37.1 2.3 2.6 6.6 0.3

0.55 – 0.70 41.4 52.7 3.7 4.4 7.7 2.3

0.70 – 1.00 55.0 65.5 11.3 10.5 15.1 12.5

1.00 – 1.30 69.4 85.3 13.0 11.5 16.8 14.5

1.30 – 1.60 76.0 90.3 19.3 17.6 22.4 20.6

1.60 – 2.20 79.2 93.0 29.8 27.5 33.5 33.8

2.20 – 3.00 77.4 93.8 47.2 45.6 51.2 52.4

3.00 – 4.00 73.2 92.9 60.1 59.7 64.9 66.0

4.00 – 5.50 66.2 90.1 72.7 73.4 76.6 76.3

5.50 – 7.00 63.8 79.2 77.0 79.0 82.3 81.1

7.00 – 10.00 55.7 60.9 73.4 78.0 79.5 76.2

E1 (0.30 – 1.0) 39.1 48.3 4.7 4.7 8.6 3.8

E2 (1.0 – 3.0) 75.5 91.1 27.3 25.6 31.0 30.3

E3 (3.0 – 10.0) 64.7 81.3 70.8 72.5 75.8 74.9

MERV rating from vendor 8 8 8 8 8 8

MERV rating from testing 7 8 8 8 8 8
G-6

Table G-6. Measured Pressure Drops During Aging of a Commercial 24" x 24" x 2"

Pleated Electrostatic Filter (C17FPP-8)

Weeks of Use

(hours of operation)

Mass Gained 

(g)

Measured Pressure Drop (in. w.g.)

984 cfm

(246 fpm)

1476 cfm

(369 fpm)

1968 cfm

(492 fpm)

2460 cfm

(615 fpm)

0 (0) (12” x 24” filter) 0 0.20 0.35 0.55 0.75

0 (0) 0 0.17 0.29 0.44 0.63

2 (336) 8 0.17 0.30 0.45 0.64

4 (672) 20 0.17 0.30 0.45 0.64

8 (1,344) 38 0.18 0.31 0.47 0.66

16 (2,688) 82 0.22 0.37 0.57 0.79

Manufacturer’s Pressure 

Drop Data (in. w.g.) 0.10 at 250 fpm 0.18 at 375 fpm 0.30 at 500 fpm 0.45 at 625 fpm
G-7

Table G-7. Measured Collection Efficiencies During Aging of a Commercial 24" x 24" x 2"

Pleated Electrostatic Filter (C15AAA-11)

Particle Size Range 

or Midpoint of Range 

(μm)

Particle Size Efficiency (%)

0 weeks

(12 x 24 filter) 0 weeks 2 weeks 4 weeks 8 weeks 16 weeks

0.029 36.2 45.1 16.3 15.1 11.9 14.8

0.034 35.2 50.7 10.6 10.0 14.3 13.0

0.039 35.4 48.1 9.2 8.8 12.1 10.8

0.045 36.3 44.1 6.7 4.4 11.1 5.7

0.052 32.9 42.1 3.9 5.3 11.4 5.8

0.060 30.7 39.5 0.3 0.3 9.1 3.9

0.070 31.0 34.4 0.0 0.0 10.8 2.8

0.081 29.7 32.1 0.0 0.0 11.7 2.5

0.093 27.0 29.3 0.0 0.0 12.0 0.0

0.11 26.2 29.1 0.0 0.0 11.8 0.0

0.12 25.1 26.1 0.0 0.0 11.1 0.0

0.14 23.9 25.1 0.0 0.0 12.3 0.0

0.17 20.8 21.8 0.0 0.0 14.4 0.0

0.19 22.1 22.9 0.0 0.0 14.3 0.0

0.22 22.4 22.2 0.0 0.0 11.6 0.0

0.26 22.4 16.1 0.0 0.0 14.6 0.0

0.29 20.9 17.3 0.0 0.0 13.6 0.0

0.30 – 0.40 39.6 29.0 8.2 7.1 0.9 2.9

0.40 – 0.55 40.5 35.6 8.8 8.0 0.8 4.5

0.55 – 0.70 50.6 47.1 11.6 11.3 2.1 5.2

0.70 – 1.00 59.1 52.6 15.4 14.8 9.4 12.7

1.00 – 1.30 67.6 66.4 16.5 14.2 10.4 13.2

1.30 – 1.60 73.0 71.4 23.4 22.4 15.1 19.4

1.60 – 2.20 75.2 76.5 28.0 27.1 23.7 28.1

2.20 – 3.00 75.9 73.4 39.5 37.4 37.6 43.4

3.00 – 4.00 74.7 71.3 50.3 47.4 49.9 54.2

4.00 – 5.50 71.5 70.9 64.3 60.5 62.0 65.2

5.50 – 7.00 73.0 65.4 73.4 68.1 70.6 73.1

7.00 – 10.00 66.5 58.9 76.0 71.9 71.8 74.4

E1 (0.30 – 1.0) 47.5 41.1 11.0 10.3 3.3 6.3

E2 (1.0 – 3.0) 72.9 71.9 26.8 25.3 21.7 26.0

E3 (3.0 – 10.0) 71.4 66.6 66.0 62.0 63.6 66.7

MERV rating from vendor 11 11 11 11 11 11

MERV rating from testing 8 7 7 7 7 7
G-8

Table G-8. Measured Pressure Drops During Aging of a Commercial 24" x 24" x 2"

Pleated Electrostatic Filter (C15AAA-11)

Weeks of Use

(hours of operation)

Mass 

Gained (g)

Measured Pressure Drop (in. w.g.)

984 cfm

(246 fpm)

1476 cfm

(369 fpm)

1968 cfm

(492 fpm)

2460 cfm

(615 fpm)

0 (0) (12” x 24” filter) 0 0.14 0.25 0.40 0.59

0 (0) 0 0.13 0.22 0.34 0.47

2 (336) 13 0.14 0.24 0.37 0.53

4 (672) 24 0.14 0.25 0.38 0.54

8 (1,344) 42 0.15 0.26 0.39 0.55

16 (2,688) 89 0.18 0.30 0.46 0.64

Manufacturer’s Pressure 

Drop Data (in. w.g.) 0.12 at 250 fpm 0.23 at 375 fpm 0.38 at 500 fpm 0.51 at 625 fpm
G-9

Table G-9. Measured Collection Efficiencies During Aging of a Commercial 24" x 24" x 12"

Pleated Electrostatic Box Filter (C8GZ-13)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%)

0 weeks

(Test 1)

0 weeks

(Test 2) 2 weeks 4 weeks 8 weeks 16 weeks

0.029 74.8 65.5 70.4 66.3 59.9 56.8

0.034 73.0 64.7 65.4 61.8 53.9 52.4

0.039 72.9 60.1 63.1 57.2 50.8 47.7

0.045 73.2 61.5 61.1 53.4 46.6 42.3

0.052 72.2 58.3 58.1 48.7 42.0 37.2

0.060 70.8 59.4 55.5 46.7 39.4 34.1

0.070 69.6 58.8 51.7 42.1 36.2 32.3

0.081 68.2 55.4 49.7 39.3 32.4 28.4

0.093 68.8 56.3 47.1 36.4 31.1 25.9

0.11 66.1 53.6 44.6 32.6 30.0 23.9

0.12 65.4 53.8 42.3 32.0 29.1 23.9

0.14 65.4 52.0 41.8 30.8 30.3 22.8

0.17 64.7 52.5 41.1 29.5 29.3 20.9

0.19 63.7 53.7 38.2 28.9 30.9 20.0

0.22 63.2 50.4 40.5 29.4 31.8 21.5

0.26 63.2 53.4 38.8 27.2 31.8 24.5

0.29 60.3 53.9 37.7 33.1 32.7 28.1

0.30 – 0.40 60.9 66.3 36.2 30.0 25.4 20.6

0.40 – 0.55 66.4 73.8 42.8 34.8 31.5 23.8

0.55 – 0.70 72.5 81.7 48.9 41.5 37.2 29.7

0.70 – 1.00 77.7 88.3 56.2 48.4 44.5 35.8

1.00 – 1.30 82.3 94.0 62.3 54.9 51.9 41.9

1.30 – 1.60 85.5 96.1 67.1 61.0 57.4 46.9

1.60 – 2.20 90.1 97.2 76.5 71.8 68.8 56.9

2.20 – 3.00 95.2 97.9 87.3 85.0 83.2 69.0

3.00 – 4.00 97.3 98.2 93.0 91.5 90.7 77.2

4.00 – 5.50 98.5 98.4 96.7 96.3 95.8 89.1

5.50 – 7.00 99.2 98.2 98.1 98.0 98.0 95.5

7.00 – 10.00 99.6 100.0 98.8 98.8 99.0 97.5

E1 (0.30 – 1.0) 69.4 77.5 46.0 38.7 34.6 27.5

E2 (1.0 – 3.0) 88.3 96.3 73.3 68.2 65.3 53.7

E3 (3.0 – 10.0) 98.6 98.7 96.6 69.2 95.9 89.8

MERV rating from vendor 13 13 13 13 13 13

MERV rating from testing 12 14 11 11 11 10
G-10

Table G-10. Measured Pressure Drops During Aging of a Commercial 24" x 24" x 12"

Pleated Electrostatic Box Filter (C8GZ-13)

Weeks of Use

(hours of operation)

Mass Gained 

(g)

Measured Pressure Drop (in. w.g.)

984 cfm

(246 fpm)

1476 cfm

(369 fpm)

1968 cfm

(492 fpm)

2460 cfm

(615 fpm)

0 (0) (Test 1) 0 0.25 0.40 0.59 0.80

0 (0) (Test 2) 0 0.26 0.43 0.63 0.89

2 (336) 9 0.25 0.41 0.59 0.80

4 (672) 14 0.25 0.40 0.57 0.79

8 (1,344) 32 0.25 0.40 0.57 0.78

16 (2,688) 50 0.25 0.40 0.58 0.78

Manufacturer’s Pressure 

Drop Data (in. w.g.) NA NA 0.44 at 500 fpm NA
G-11

Table G-11. Measured Collection Efficiencies During Aging of a Commercial 24" x 24" x 12"

Pleated Non-Electrostatic Filter (C14PCS)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%)

0 weeks 2 weeks 4 weeks 8 weeks 16 weeks

0.029 85.4 85.9 82.9 88.3 88.8

0.034 83.6 83.3 81.4 86.2 88.1

0.039 80.3 80.8 77.9 83.9 87.4

0.045 77.1 78.0 76.0 80.7 85.5

0.052 73.7 74.8 72.1 78.3 84.3

0.060 71.5 71.7 69.3 75.7 82.5

0.070 67.5 69.3 66.1 73.0 81.9

0.081 65.3 66.6 63.3 70.3 81.1

0.093 63.6 64.6 62.0 69.2 80.0

0.11 61.1 63.5 60.8 68.2 79.9

0.12 60.6 63.5 60.5 67.3 80.6

0.14 61.7 63.5 60.3 68.2 81.4

0.17 61.6 65.1 62.0 68.5 82.5

0.19 60.0 65.3 61.6 69.1 82.8

0.22 63.8 69.0 65.5 72.1 83.9

0.26 64.3 67.8 64.6 72.9 85.4

0.29 66.6 68.5 64.7 75.0 86.9

0.30 – 0.40 62.0 72.1 64.5 70.8 77.0

0.40 – 0.55 68.6 76.9 70.7 75.9 80.7

0.55 – 0.70 74.4 81.3 75.9 80.5 86.4

0.70 – 1.00 80.2 85.5 81.5 85.1 91.2

1.00 – 1.30 84.0 88.4 85.7 87.9 95.5

1.30 – 1.60 86.7 90.6 87.9 90.0 96.8

1.60 – 2.20 91.3 93.8 91.8 93.2 98.1

2.20 – 3.00 95.7 97.1 95.8 96.5 98.7

3.00 – 4.00 97.6 98.4 97.6 97.9 98.9

4.00 – 5.50 98.6 99.2 98.5 98.6 99.1

5.50 – 7.00 99.1 99.9 99.0 99.1 99.4

7.00 – 10.00 99.3 100.0 99.4 99.3 100.0

E1 (0.30 – 1.0) 71.3 79.0 73.2 78.1 83.8

E2 (1.0 – 3.0) 89.4 92.5 90.3 91.9 97.3

E3 (3.0 – 10.0) 98.6 99.4 98.6 98.7 99.3

MERV rating from vendor 14 14 14 14 14

MERV rating from testing 12 14 13 14 14
G-12

Table G-12. Measured Pressure Drops During Aging of a Commercial 24" x 24" x 12"

Pleated Non-Electrostatic Filter (C14PCS)

Weeks of Use

(hours of operation)

Mass Gained 

(g)

Measured Pressure Drop (in. w.g.)

984 cfm

(246 fpm)

1476 cfm

(369 fpm)

1968 cfm

(492 fpm)

2460 cfm

(615 fpm)

0 (0) 0 0.24 0.41 0.60 0.83

2 (336) 17 0.25 0.42 0.62 0.84

4 (672) 26 0.26 0.42 0.62 0.84

8 (1,344) 39 0.27 0.44 0.64 0.87

16 (2,688) 76 0.28 0.46 0.66 0.89

Manufacturer’s Pressure 

Drop Data (in. w.g.) 0.25 at 250 fpm 0.40 at 375 fpm 0.60 at 500 fpm 0.78 at 625 fpm
G-13

Table G-13. Measured Collection Efficiencies During Aging of a Commercial 24" x 24" x 12" 

Pleated Non-Electrostatic Filter (C11GM-16)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%)

0 weeks 2 weeks 4 weeks 8 weeks 16 weeks

0.029 99.9 99.7 99.8 99.8 99.9

0.034 99.8 99.6 99.8 99.6 99.8

0.039 99.7 99.5 99.5 99.5 99.5

0.045 99.4 99.4 99.3 99.3 99.4

0.052 99.0 99.3 98.9 98.8 98.9

0.060 98.4 99.0 98.5 98.3 98.4

0.070 97.7 98.7 97.8 97.6 97.8

0.081 96.9 98.5 97.1 96.8 97.2

0.093 96.2 98.1 96.5 96.1 96.4

0.11 95.6 98.0 95.9 95.4 95.9

0.12 95.0 97.6 95.1 94.8 95.2

0.14 94.9 97.5 95.0 94.3 94.9

0.17 94.9 97.3 95.1 94.8 94.9

0.19 95.2 97.3 95.0 95.1 95.0

0.22 94.9 97.5 95.5 95.4 95.6

0.26 95.1 97.3 95.6 96.0 95.7

0.29 96.3 97.6 95.9 95.9 96.7

0.30 – 0.40 97.0 97.0 97.2 97.5 98.1

0.40 – 0.55 98.4 98.4 98.6 98.6 99.2

0.55 – 0.70 99.2 99.2 99.3 99.2 99.7

0.70 – 1.00 99.6 99.6 99.7 99.5 99.9

1.00 – 1.30 99.8 99.8 99.8 99.8 99.9

1.30 – 1.60 99.9 99.9 99.9 99.9 100.0

1.60 – 2.20 99.9 99.9 99.9 99.9 100.0

2.20 – 3.00 100.0 100.0 100.0 99.9 100.0

3.00 – 4.00 100.0 100.0 100.0 99.9 100.0

4.00 – 5.50 100.0 100.0 100.0 99.9 100.0

5.50 – 7.00 100.0 100.0 100.0 99.9 100.0

7.00 – 10.00 100.0 100.0 100.0 99.9 100.0

E1 (0.30 – 1.0) 98.6 98.5 98.7 98.7 99.2

E2 (1.0 – 3.0) 99.9 99.9 99.9 99.9 100

E3 (3.0 – 10.0) 100 100 100 99.9 100

MERV rating from vendor 16 16 16 16 16

MERV rating from testing 16 16 16 16 16
G-14

Table G-14. Measured Pressure Drops During Aging of a Commercial 24" x 24" x 12"

Pleated Non-Electrostatic Filter (C11GM-16)

Weeks of Use

(hours of operation)

Mass Gained 

(g)

Measured Pressure Drop (in. w.g.)

984 cfm

(246 fpm)

1476 cfm

(369 fpm)

1968 cfm

(492 fpm)

2460 cfm

(615 fpm)

0 (0) 0 0.37 0.59 0.85 1.14

2 (336) 11 0.36 0.58 0.84 1.13

4 (672) 22 0.35 0.57 0.83 1.11

8 (1,344) 42 0.36 0.58 0.83 1.12

16 (2,688) 81 0.37 0.60 0.86 1.16

Manufacturer’s Pressure 

Drop Data (in. w.g.) 0.42 at 250 fpm 0.55 at 375 fpm 0.61 at 500 fpm NA
G-15

Table G-15. Measured Collection Efficiencies During Aging of a Residential Electronic Air Cleaner (Unit A)

Particle Size Range 

or Midpoint of Range 

(μm)

Particle Size Efficiency (%)

0 weeks 2 weeks 4 weeks 8 weeks 16 weeks

0.029 93.1 91.7 90.8 84.0 81.4

0.034 92.5 90.6 90.7 82.3 81.1

0.039 92.3 90.7 90.8 81.8 80.6

0.045 91.6 90.4 91.3 80.8 80.2

0.052 91.0 89.3 91.3 79.7 79.6

0.060 90.5 88.9 91.1 77.8 78.5

0.070 89.7 87.5 91.3 77.1 77.5

0.081 89.0 87.2 90.8 75.8 76.7

0.093 88.3 86.2 90.4 74.7 76.5

0.11 88.1 86.1 90.3 72.2 76.1

0.12 87.3 85.9 90.2 71.6 75.4

0.14 86.8 85.7 90.2 69.7 75.5

0.17 85.6 84.8 89.8 69.5 76.5

0.19 85.0 84.6 89.4 69.3 76.9

0.22 84.2 83.2 89.4 70.3 77.4

0.26 84.7 83.4 89.2 70.3 79.2

0.29 83.5 84.3 88.8 70.6 79.2

0.30 – 0.40 80.8 85.6 84.4 77.5 73.4

0.40 – 0.55 82.8 87.2 86.4 81.6 77.8

0.55 – 0.70 85.4 89.2 88.6 85.2 83.3

0.70 – 1.00 87.7 91.1 90.8 88.7 88.1

1.00 – 1.30 90.6 93.0 93.2 91.8 92.0

1.30 – 1.60 91.9 94.0 94.3 92.9 93.4

1.60 – 2.20 94.1 95.0 95.4 94.2 94.5

2.20 – 3.00 95.6 96.1 96.2 95.5 95.1

3.00 – 4.00 96.7 96.9 97.0 96.3 95.9

4.00 – 5.50 97.8 97.3 98.0 96.8 96.8

5.50 – 7.00 98.0 97.9 98.4 97.7 96.7

7.00 – 10.00 99.2 97.0 99.5 96.4 97.6

E1 (0.30 – 1.0) 84.2 88.3 87.6 83.2 80.7

E2 (1.0 – 3.0) 93.1 94.5 94.8 93.6 93.8

E3 (3.0 – 10.0) 97.9 97.3 98.2 96.8 96.8

MERV rating from vendor 15 15 15 15 15

MERV rating from testing 14 15 15 14 14
G-16

Table G-16. Measured Pressure Drops During Aging of a Residential Electronic Air Cleaner (Unit A)

Weeks of Use

 (hours of operation)

Measured Pressure Drop (in. w.g.)

410 cfm

(148 fpm)

614 cfm

(221 fpm)

820 cfm

(295 fpm)

1024 cfm

(369 fpm)

0 (0) 0.05 0.08 0.12 0.17

1 (168) 0.06 0.10 0.16 0.24

2 (336) 0.06 0.08 0.12 0.17

6 (1,008) 0.07 0.11 0.16 0.22

12 (2,016) 0.08 0.11 0.15 0.17

Manufacturer’s Pressure 

Drop Data (in. w.g.) NA NA 0.10 at 360 fpm 0.17 at 504 fpm
G-17

Table G-17. Measured Collection Efficiencies During Aging of a Residential Electronic Air Cleaner (Unit H)

Particle Size Range 

or Midpoint of Range 

(μm)

Particle Size Efficiency (%)

0 weeks 2 weeks 4 weeks 8 weeks 16 weeks

0.029 93.8 93.0 91.8 77.6 64.5

0.034 94.5 94.3 92.3 82.4 67.7

0.039 94.8 94.1 92.0 84.5 71.5

0.045 94.4 93.5 91.1 85.1 72.4

0.052 93.6 92.6 90.0 84.2 71.4

0.060 92.8 91.9 89.0 82.9 70.3

0.070 91.9 90.2 88.6 82.1 67.9

0.081 91.4 88.3 87.1 80.8 66.2

0.093 90.2 86.8 86.4 79.8 64.2

0.11 89.4 86.0 86.1 78.1 62.8

0.12 88.8 85.7 85.9 77.5 61.5

0.14 88.5 86.5 85.3 76.4 60.5

0.17 87.2 86.4 85.9 77.2 60.0

0.19 88.5 86.7 86.4 77.2 61.0

0.22 87.8 85.7 86.1 78.1 59.8

0.26 87.5 85.8 87.1 79.0 62.0

0.29 87.1 86.0 87.3 79.9 62.3

0.30 – 0.40 89.3 88.7 90.0 80.0 67.9

0.40 – 0.55 91.9 91.7 92.9 85.3 71.4

0.55 – 0.70 94.0 94.3 94.9 89.5 77.3

0.70 – 1.00 95.5 95.8 96.0 92.5 82.3

1.00 – 1.30 96.5 96.8 96.8 94.4 86.6

1.30 – 1.60 96.6 97.1 97.1 95.1 88.8

1.60 – 2.20 97.1 97.4 97.2 95.9 90.4

2.20 – 3.00 97.4 97.7 97.7 96.7 91.9

3.00 – 4.00 97.6 97.9 98.1 97.5 93.6

4.00 – 5.50 98.0 98.1 98.4 97.9 94.6

5.50 – 7.00 98.0 98.2 98.3 99.1 94.8

7.00 – 10.00 98.8 99.1 98.0 97.8 95.3

E1 (0.30 – 1.0) 92.7 92.6 93.4 86.8 74.7

E2 (1.0 – 3.0) 96.9 97.3 97.2 95.6 89.4

E3 (3.0 – 10.0) 98.1 98.3 98.2 98.1 94.6

MERV rating from vendor 12 at 492 fpm 12 at 492 fpm 12 at 492 fpm 12 at 492 fpm 12 at 492 fpm

MERV rating from testing 15 15 15 15 12
G-18

Table G-18. Measured Pressure Drops During Aging of a Residential Electronic Air Cleaner (Unit H)

Weeks of Use

(hours of operation)

Measured Pressure Drop (in. w.g.)

410 cfm

(148 fpm)

614 cfm

(221 fpm)

820 cfm

(295 fpm)

1024 cfm

(369 fpm)

0 (0) 0.03 0.06 0.11 0.17

1 (168) 0.03 0.06 0.09 0.13

2 (336) 0.05 0.09 0.13 0.18

6 (1,008) 0.05 0.09 0.13 0.20

12 (2,016) 0.05 0.08 0.13 0.19

Manufacturer’s Pressure 

Drop Data (in. w.g.) 0.03 at 148 fpm 0.04 at 221 fpm 0.06 at 295 fpm 0.09 at 369 fpm
G-19

Table G-19. Measured Collection Efficiencies During Aging of a Residential Electronic Air Cleaner (Unit P)

Particle Size Range 

or Midpoint of Range 

(μm)

Particle Size Efficiency (%)

0 weeks 2 weeks 4 weeks 8 weeks 16 weeks

0.029 81.2 83.9 76.3 47.7 21.7

0.034 84.4 86.6 77.9 47.4 26.1

0.039 88.2 87.6 78.0 48.5 23.0

0.045 88.5 87.0 77.6 45.4 24.0

0.052 87.9 86.0 76.5 41.4 20.8

0.060 86.7 85.3 74.0 37.8 17.9

0.070 85.5 82.7 72.7 34.6 13.4

0.081 83.7 81.0 70.9 30.8 9.7

0.093 81.7 78.7 68.7 26.2 8.1

0.11 80.9 77.3 67.7 24.7 7.1

0.12 80.1 76.3 67.1 22.6 6.4

0.14 78.5 76.1 66.8 18.3 4.1

0.17 79.0 75.1 66.3 17.7 4.9

0.19 77.5 74.3 67.1 14.4 3.7

0.22 80.0 73.2 67.5 13.6 2.7

0.26 79.7 74.3 67.1 10.5 2.7

0.29 80.8 72.2 67.9 10.1 0.0

0.30 – 0.40 76.7 74.1 69.6 15.6 5.1

0.40 – 0.55 82.1 80.0 76.0 17.4 4.3

0.55 – 0.70 86.5 85.4 81.7 19.0 3.3

0.70 – 1.00 90.5 89.5 86.7 21.5 3.9

1.00 – 1.30 93.6 93.0 90.8 24.8 5.4

1.30 – 1.60 94.9 94.3 92.6 25.6 4.9

1.60 – 2.20 95.7 95.3 94.1 28.3 6.5

2.20 – 3.00 96.2 96.4 95.3 32.1 5.6

3.00 – 4.00 96.6 97.1 96.1 37.8 12.8

4.00 – 5.50 97.0 97.2 96.7 44.8 18.6

5.50 – 7.00 97.6 97.9 96.9 48.0 24.9

7.00 – 10.00 97.1 98.4 97.4 56.5 31.0

E1 (0.30 – 1.0) 84.0 82.3 78.5 18.4 4.1

E2 (1.0 – 3.0) 95.1 94.7 93.2 27.7 5.6

E3 (3.0 – 10.0) 97.1 97.6 96.8 46.8 21.8

MERV rating from vendor NA NA NA NA NA

MERV rating from testing 14 14 14 6 5
G-20

Table G-20. Measured Pressure Drops During Aging of a Residential Electronic Air Cleaner (Unit P)

Weeks of Use

(hours of operation)

Measured Pressure Drop (in. w.g.)

410 cfm

(148 fpm)

614 cfm

(221 fpm)

820 cfm

(295 fpm)

1024 cfm

(369 fpm)

0 (0) 0.02 0.04 0.06 0.09

1 (168) 0.02 0.03 0.05 0.06

2 (336) 0.02 0.03 0.05 0.08

6 (1,008) 0.03 0.04 0.07 0.10

12 (2,016) 0.02 0.04 0.06 0.08

Manufacturer’s Pressure 

Drop Data (in. w.g.) NA NA NA 0.11 at 504 fpm
H-1

Appendix H

Results From the Inert Aerosol Evaluations

of the Conditioned Air Cleaners

Table H-1. Measured Collection Efficiencies During Conditioning of a Residential 16" x 25" x 1"

Pleated Electrostatic Filter (6DDUE-8)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%)

Unloaded

After CT of 3.2 * 107

(particles*min) / cm3

After CT of 6.9 * 107

(particles*min) / cm3

After CT of 1.0 * 108

(particles*min) / cm3

0.029 25.0 16.9 20.6 14.7

0.034 33.8 27.4 32.4 24.2

0.039 30.8 26.6 29.1 20.4

0.045 28.0 22.9 26.8 17.6

0.052 27.1 22.6 24.0 17.2

0.060 25.7 21.3 23.5 17.0

0.070 23.0 18.8 23.4 14.8

0.081 22.3 17.0 21.5 15.7

0.093 22.3 17.0 21.2 15.4

0.11 23.6 18.2 22.6 15.8

0.12 23.3 17.2 22.9 15.5

0.14 23.2 15.1 22.4 16.1

0.17 21.8 14.3 21.5 14.0

0.19 25.4 16.1 23.1 17.3

0.22 25.3 13.8 23.9 15.3

0.26 18.2 8.0 17.3 8.0

0.29 18.1 4.3 14.2 7.9

0.30 – 0.40 16.1 12.0 9.0 12.3

0.40 – 0.55 14.0 10.4 9.1 12.9

0.55 – 0.70 21.4 16.3 14.9 21.6

0.70 – 1.00 31.1 30.8 29.4 36.7

1.00 – 1.30 44.8 51.0 50.1 59.3

1.30 – 1.60 50.6 64.6 63.6 70.3

1.60 – 2.20 55.6 77.6 77.7 83.2

2.20 – 3.00 56.8 86.2 85.4 88.9

3.00 – 4.00 57.6 90.3 87.8 91.3

4.00 – 5.50 55.5 90.0 89.0 92.3

5.50 – 7.00 59.2 88.4 87.7 93.0

7.00 – 10.00 54.9 86.5 84.8 92.9

E1 (0.30 – 1.0) 20.6 17.4 15.6 20.9

E2 (1.0 – 3.0) 51.9 69.9 69.2 75.4

E3 (3.0 – 10.0) 56.8 88.8 87.3 92.4

MERV rating from vendor 8 8 8 8

MERV rating from testing 7 11 11 11
H-2

Table H-2. Measured Collection Efficiencies During Conditioning of a Residential 16" x 25" x 1"

Pleated Electrostatic Filter (8NM-10)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%)

Unloaded

After CT of 5.0 * 107

(particles*min) / cm3

After CT of 7.5 * 107

(particles*min) / cm3

After CT of 1.1 * 108

(particles*min) / cm3

0.029 22.7 12.7 18.8

0.034 20.2 9.8 17.4

0.039 18.5 6.9 15.0

0.045 17.9 7.4 13.9

0.052 15.5 5.9 14.0

0.060 13.8 4.7 12.7

0.070 13.1 2.8 11.5

0.081 13.1 2.9 10.1

0.093 11.8 1.8 11.2

0.11 10.8 1.1 9.5

0.12 9.4 1.1 6.8

0.14 10.6 1.3 9.1

0.17 10.0 0.0 9.1

0.19 7.9 0.0 10.9

0.22 13.6 5.8 13.4

0.26 12.6 0.5 13.5

0.29 18.0 7.2 20.0

0.30 – 0.40 16.9 5.9 16.5 33.3

0.40 – 0.55 20.5 15.0 20.6 33.9

0.55 – 0.70 33.8 28.8 34.4 49.2

0.70 – 1.00 53.7 49.0 54.5 68.1

1.00 – 1.30 72.4 68.3 73.2 83.3

1.30 – 1.60 80.4 76.8 80.5 87.8

1.60 – 2.20 86.8 84.1 85.7 91.9

2.20 – 3.00 89.8 86.8 88.2 94.0

3.00 – 4.00 91.0 87.7 88.3 95.2

4.00 – 5.50 91.5 86.8 87.7 94.8

5.50 – 7.00 91.3 85.5 87.3 93.6

7.00 – 10.00 91.8 83.0 84.4 93.2

E1 (0.30 – 1.0) 31.2 24.7 31.5 46.1

E2 (1.0 – 3.0) 82.4 79.0 81.9 89.3

E3 (3.0 – 10.0) 91.4 85.8 86.9 94.2

MERV rating from vendor 10 10 10 10

MERV rating from testing 12 11 11 12
H-3

Table H-3. Measured Collection Efficiencies During Conditioning of a Commercial 24" x 24" x 2"

Pleated Electrostatic Filter (C17FPP-8)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%)

Unloaded

After CT of 3.2 * 107

(particles*min) / cm3

After CT of 6.6 * 107

(particles*min) / cm3

0.029 29.7 38.6 17.0

0.034 34.8 31.0 13.2

0.039 30.1 33.1 16.6

0.045 28.0 30.3 12.0

0.052 22.0 26.7 14.3

0.060 20.9 29.5 17.1

0.070 17.5 24.5 15.3

0.081 18.4 24.8 16.7

0.093 14.4 21.5 18.6

0.11 12.7 21.2 19.9

0.12 11.9 22.9 16.4

0.14 15.3 17.5 18.6

0.17 12.0 13.6 19.8

0.19 13.5 25.1 24.4

0.22 8.1 16.3 15.4

0.26 15.0 24.9 28.8

0.29 16.4 22.2 26.0

0.30 – 0.40 34.5 37.9 39.6

0.40 – 0.55 39.9 41.1 40.7

0.55 – 0.70 52.3 55.9 54.2

0.70 – 1.00 66.7 72.0 72.3

1.00 – 1.30 86.7 90.0 90.1

1.30 – 1.60 90.6 94.3 93.6

1.60 – 2.20 93.3 96.7 96.3

2.20 – 3.00 93.8 97.5 98.2

3.00 – 4.00 92.2 97.9 98.2

4.00 – 5.50 89.0 98.5 97.9

5.50 – 7.00 62.7 NA NA

7.00 – 10.00 NA NA NA

E1 (0.30 – 1.0) 48.3 51.7 51.7

E2 (1.0 – 3.0) 91.1 94.6 94.6

E3 (3.0 – 10.0) 81.3 98.2 98.0

MERV rating from vendor 8 8 8

MERV rating from testing 8 13 13
H-4

Table H-4. Measured Collection Efficiencies During Conditioning of a Commercial 24" x 24" x 2"

Pleated Electrostatic Filter (C15AAA-11)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%)

Unloaded

After CT of 3.2 * 107

(particles*min) / cm3

After CT of 8.0 * 107

(particles*min) / cm3

After CT of 1.1 * 108

(particles*min) / cm3

0.029 45.1 9.9 23.2 16.8

0.034 50.7 11.4 23.8 24.9

0.039 48.1 11.7 22.8 24.8

0.045 44.1 9.6 18.2 22.1

0.052 42.1 11.7 15.0 19.3

0.060 39.5 10.9 12.6 18.1

0.070 34.4 9.5 11.5 16.5

0.081 32.1 9.7 9.9 15.3

0.093 29.3 11.8 10.6 14.9

0.11 29.1 10.7 8.8 15.9

0.12 26.1 9.4 6.9 14.4

0.14 25.1 10.3 3.8 13.5

0.17 21.8 8.3 2.0 10.3

0.19 22.9 10.6 3.1 12.1

0.22 22.2 10.0 2.4 10.5

0.26 16.1 12.7 0.0 2.6

0.29 17.3 11.7 0.0 0.0

0.30 – 0.40 29.0 13.7 10.8 8.1

0.40 – 0.55 35.6 23.6 18.9 20.0

0.55 – 0.70 47.1 36.6 31.1 33.6

0.70 – 1.00 52.6 44.2 37.8 41.1

1.00 – 1.30 66.4 63.1 56.8 60.6

1.30 – 1.60 71.4 72.6 67.7 69.8

1.60 – 2.20 76.5 83.4 78.3 81.0

2.20 – 3.00 73.4 85.6 80.4 81.8

3.00 – 4.00 71.3 86.6 80.8 82.7

4.00 – 5.50 70.9 88.2 81.0 83.4

5.50 – 7.00 65.4 88.8 78.9 86.2

7.00 – 10.00 58.9 90.7 78.5 87.7

E1 (0.30 – 1.0) 41.1 29.5 24.6 25.7

E2 (1.0 – 3.0) 71.9 76.2 70.8 73.3

E3 (3.0 – 10.0) 66.6 88.6 79.8 85.0

MERV rating from vendor 11 11 11 11

MERV rating from testing 7 11 8 11
H-5

Table H-5. Measured Collection Efficiencies During Conditioning of a Commercial 24" x 24" x 12"

Pleated Electrostatic Box Filter (C8GZ-13)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%)

Unloaded

After CT of 3.2 * 107

(particles*min) / cm3

After CT of 6.4 * 107

(particles*min) / cm3

After CT of 9.6 * 107

(particles*min) / cm3

0.029 65.5 72.7 76.4 77.6

0.034 64.7 74.3 75.0 76.9

0.039 60.1 72.9 72.2 76.4

0.045 61.5 72.3 72.1 76.7

0.052 58.3 72.2 68.8 73.1

0.060 59.4 69.2 69.1 73.8

0.070 58.8 72.0 69.3 74.1

0.081 55.4 70.3 65.6 71.6

0.093 56.3 65.2 64.7 70.5

0.11 53.6 66.2 63.5 69.8

0.12 53.8 64.2 61.7 67.7

0.14 52.0 63.0 61.3 70.1

0.17 52.5 61.7 60.7 66.5

0.19 53.7 61.2 59.7 66.4

0.22 50.4 62.9 59.7 69.7

0.26 53.4 58.4 59.9 65.2

0.29 53.9 56.7 58.6 67.2

0.30 – 0.40 66.3 59.5 63.7 60.0

0.40 – 0.55 73.8 69.4 70.7 68.6

0.55 – 0.70 81.7 79.0 80.1 78.3

0.70 – 1.00 88.3 87.0 87.7 86.5

1.00 – 1.30 94.0 93.9 94.4 93.8

1.30 – 1.60 96.1 96.3 96.6 96.5

1.60 – 2.20 97.2 97.9 98.1 98.0

2.20 – 3.00 97.9 98.6 98.5 98.5

3.00 – 4.00 98.2 98.8 98.7 98.6

4.00 – 5.50 98.4 98.9 98.8 98.6

5.50 – 7.00 98.2 98.2 96.9 99.1

7.00 – 10.00 100.0

E1 (0.30 – 1.0) 77.5 73.7 75.6 73.4

E2 (1.0 – 3.0) 96.3 96.7 96.9 96.7

E3 (3.0 – 10.0) 98.7 98.6 98.1 98.8

MERV rating from vendor 13 13 13 13

MERV rating from testing 14 13 14 13
H-6

Table H-6. Measured Collection Efficiencies During Conditioning of a Residential 16" x 25" x 1"

Pleated Electrostatic Filter (5RM-11-1)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%)

Unloaded

After CT of 3.4 * 107

(particles*min) / cm3

After CT of 6.6 * 107

(particles*min) / cm3

0.029 35.5 5.9 24.0

0.034 31.8 9.6 26.4

0.039 27.5 11.4 26.9

0.045 26.5 11.7 27.4

0.052 23.6 10.0 28.1

0.060 22.3 10.1 28.0

0.070 19.7 10.8 29.7

0.081 17.5 11.4 31.6

0.093 16.0 11.5 31.7

0.11 15.7 13.2 32.4

0.12 14.9 11.4 33.8

0.14 11.8 11.8 34.3

0.17 12.3 11.1 36.2

0.19 9.4 10.2 36.2

0.22 12.6 16.5 40.3

0.26 8.7 14.6 40.3

0.29 15.7 19.5 45.0

0.30 – 0.40 14.7 11.5 14.2

0.40 – 0.55 11.7 8.9 10.4

0.55 – 0.70 17.1 13.9 17.3

0.70 – 1.00 33.3 28.9 34.3

1.00 – 1.30 52.9 50.3 56.8

1.30 – 1.60 62.5 63.4 69.2

1.60 – 2.20 71.2 77.5 83.8

2.20 – 3.00 72.9 84.2 90.7

3.00 – 4.00 69.4 85.4 92.4

4.00 – 5.50 66.5 86.0 93.9

5.50 – 7.00 68.2 87.9 94.9

7.00 – 10.00 70.4 87.9 95.2

E1 (0.30 – 1.0) 19.2 15.8 19.1

E2 (1.0 – 3.0) 64.9 68.8 75.1

E3 (3.0 – 10.0) 68.7 86.8 94.1

MERV rating from vendor 11 11 11

MERV rating from testing 7 11 11
H-7

Table H-7. Measured Collection Efficiencies During Conditioning of a Residential 16" x 25" x 1"

Pleated Electrostatic Filter (4FUA-12-3)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%)

Unloaded

After CT of 3.3 * 107

(particles*min) / cm3

After CT of 6.8* 107

(particles*min) / cm3

After CT of 1.1 * 108

(particles*min) / cm3

0.029 48.3 51.4 30.0 43.4

0.034 50.8 49.6 28.9 41.0

0.039 49.3 48.5 28.6 37.2

0.045 48.2 47.3 26.6 35.5

0.052 46.0 46.4 23.4 32.2

0.060 43.9 46.4 22.7 29.4

0.070 42.1 45.8 21.0 27.5

0.081 40.7 44.8 19.3 25.5

0.093 40.1 45.7 17.9 24.8

0.11 38.3 45.1 17.7 24.0

0.12 36.5 45.2 18.5 22.7

0.14 34.8 45.9 18.4 22.3

0.17 33.0 47.3 17.4 22.2

0.19 32.0 47.6 17.3 21.7

0.22 34.7 50.2 24.5 25.9

0.26 32.4 48.6 23.2 27.7

0.29 34.8 52.4 28.0 30.8

0.30 – 0.40 30.4 23.8 23.5 27.3

0.40 – 0.55 32.1 25.6 23.9 26.0

0.55 – 0.70 41.2 33.5 31.1 33.4

0.70 – 1.00 55.0 47.6 45.4 48.2

1.00 – 1.30 69.8 65.6 62.7 66.0

1.30 – 1.60 77.7 75.2 73.7 77.2

1.60 – 2.20 86.2 87.3 86.1 87.9

2.20 – 3.00 89.5 92.7 92.3 93.8

3.00 – 4.00 90.4 94.4 94.3 95.5

4.00 – 5.50 90.4 96.2 96.0 96.6

5.50 – 7.00 93.3 97.4 97.8 97.6

7.00 – 10.00 94.3 97.4 98.3 99.7

E1 (0.30 – 1.0) 39.7 32.6 31.0 33.7

E2 (1.0 – 3.0) 80.8 80.2 78.7 81.2

E3 (3.0 – 10.0) 92.1 96.4 96.6 97.4

MERV rating from vendor 12 12 12 12

MERV rating from testing 12 12 11 12
H-8

Table H-8. Measured Collection Efficiencies During Conditioning of a Residential 16" x 25" x 1"

Pleated Electrostatic Filter (7AST-8-3)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%)

Unloaded

After CT of 3.2 * 107

(particles*min) / cm3

After CT of 6.9* 107

(particles*min) / cm3

After CT of 1.0 * 108

(particles*min) / cm3

0.029 37.2 15.0 26.2 32.0

0.034 36.6 16.1 26.4 32.3

0.039 33.7 11.5 23.7 27.9

0.045 31.8 10.1 18.8 26.3

0.052 30.3 7.6 14.7 25.5

0.060 28.6 4.1 15.6 23.2

0.070 26.7 2.5 14.7 23.2

0.081 23.9 1.0 12.0 21.5

0.093 22.6 0.0 12.1 21.0

0.11 22.8 0.0 11.8 21.8

0.12 20.4 0.0 11.1 20.8

0.14 20.5 0.0 10.7 20.0

0.17 22.5 0.0 10.2 22.7

0.19 21.6 0.0 11.2 23.7

0.22 21.0 0.0 9.4 23.6

0.26 23.8 0.0 10.6 25.4

0.29 18.3 0.0 7.5 24.7

0.30 – 0.40 9.4 6.6 13.0 19.4

0.40 – 0.55 10.8 9.5 12.5 21.3

0.55 – 0.70 19.6 17.7 20.9 33.8

0.70 – 1.00 36.2 35.1 40.4 56.4

1.00 – 1.30 54.2 56.4 63.4 76.9

1.30 – 1.60 61.7 67.9 74.1 85.7

1.60 – 2.20 67.5 78.9 84.0 92.2

2.20 – 3.00 66.9 84.7 89.5 95.5

3.00 – 4.00 64.2 86.4 91.1 96.7

4.00 – 5.50 60.4 86.3 90.3 97.8

5.50 – 7.00 62.9 85.4 89.2 99.1

7.00 – 10.00 57.8 88.4 88.5 93.0

E1 (0.30 – 1.0) 19.0 17.2 21.7 32.7

E2 (1.0 – 3.0) 62.6 72.0 77.8 87.6

E3 (3.0 – 10.0) 61.3 86.6 89.8 96.7

MERV rating from vendor 8 8 8 8

MERV rating from testing 7 11 11 12
H-9

Table H-9. Measured Collection Efficiencies and Pressure Drops During Conditioning of a Residential

Electronic Air Cleaner (Unit A)

Particle Size Range 

or Midpoint of Range 

(μm)

Particle Size Efficiency (%) Measured Pressure Drop (in. w.g.)

Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

Before 

Silicon Vapor 

Exposure

After Silicon Vapor 

Exposure

Before Silicon 

Vapor Exposure

After Silicon Vapor 

Exposure

0.029 95.1 87.6 0.05 @ 148 fpm 0.06 @ 148 fpm NA

0.034 95.1 87.9 0.07 @ 221 fpm 0.09 @ 221 fpm NA

0.039 95.4 88.4 0.11 @ 295 fpm 0.13 @ 295 fpm 0.10 @ 360 fpm

0.045 95.2 88.4 0.15 @ 369 fpm 0.19 @ 369 fpm 0.17 @ 504 fpm

0.052 94.9 88.8

0.060 94.6 87.1

0.070 94.6 87.3

0.081 94.2 86.9

0.093 94.3 84.9

0.11 94.2 85.2

0.12 93.9 84.4

0.14 93.7 84.5

0.17 93.3 83.2

0.19 93.1 84.0

0.22 92.8 84.1

0.26 93.7 84.5

0.29 93.3 83.2

0.30 – 0.40 89.3 83.9

0.40 – 0.55 90.3 85.7

0.55 – 0.70 91.4 87.3

0.70 – 1.00 92.2 89.6

1.00 – 1.30 93.4 91.8

1.30 – 1.60 94.0 93.2

1.60 – 2.20 94.8 94.6

2.20 – 3.00 95.4 96.2

3.00 – 4.00 96.1 97.3

4.00 – 5.50 96.9 98.0

5.50 – 7.00 97.0 98.8

7.00 – 10.00 96.3 NA

E1 (0.30 – 1.0) 90.8 86.6

E2 (1.0 – 3.0) 94.4 93.9

E3 (3.0 – 10.0) 96.6 98.1

MERV rating from vendor 15 15

MERV rating from testing 15 15
H-10

Table H-10. Measured Collection Efficiencies and Pressure Drops During Conditioning of a Residential

Electronic Air Cleaner (Unit H)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%) Measured Pressure Drop (in. w.g.) Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

Before Silicon 

Vapor Exposure

After Silicon 

Vapor Exposure

Before Silicon 

Vapor Exposure

After Silicon 

Vapor Exposure

0.029 92.2 67.8 0.03 @ 148 fpm 0.02 @ 148 fpm 0.03 at 148 fpm

0.034 94.0 69.2 0.06 @ 221 fpm 0.03 @ 221 fpm 0.04 at 221 fpm

0.039 94.2 68.7 0.11 @ 295 fpm 0.05 @ 295 fpm 0.06 at 295 fpm

0.045 93.8 68.1 0.17 @ 369 fpm 0.07 @ 369 fpm 0.09 at 369 fpm

0.052 93.4 67.7

0.060 92.5 63.8

0.070 91.5 61.2

0.081 90.5 59.1

0.093 89.4 57.1

0.11 88.3 57.2

0.12 87.7 55.3

0.14 86.6 57.8

0.17 86.9 51.7

0.19 87.0 56.8

0.22 87.1 53.1

0.26 87.3 52.5

0.29 87.9 44.4

0.30 – 0.40 86.8 49.3

0.40 – 0.55 90.5 52.8

0.55 – 0.70 93.3 54.2

0.70 – 1.00 95.2 53.1

1.00 – 1.30 96.5 53.3

1.30 – 1.60 97.1 54.6

1.60 – 2.20 97.4 55.8

2.20 – 3.00 97.7 51.4

3.00 – 4.00 98.3 50.3

4.00 – 5.50 98.5 47.1

5.50 – 7.00 98.9 44.0

7.00 – 10.00 99.5 NA

E1 (0.30 – 1.0) 91.5 52.3

E2 (1.0 – 3.0) 97.2 53.8

E3 (3.0 – 10.0) 98.8 47.1

MERV rating from vendor Up to 12 Up to 12

MERV rating from testing 15 6
H-11

Table H-11. Measured Collection Efficiencies and Pressure Drops During Conditioning of a Residential

Electronic Air Cleaner (Unit P)

Particle Size Range or 

Midpoint of Range (μm)

Particle Size Efficiency (%) Measured Pressure Drop (in. w.g.) Manufacturer’s 

Pressure Drop 

Data (in. w.g.)

Before Silicon 

Vapor Exposure

After Silicon 

Vapor Exposure

Before Silicon 

Vapor Exposure

After Silicon 

Vapor Exposure

0.029 86.4 45.2 0.03 @ 148 fpm 0.02 @ 148 fpm NA

0.034 88.2 50.3 0.05 @ 221 fpm 0.04 @ 221 fpm NA

0.039 89.1 47.0 0.08 @ 295 fpm 0.06 @ 295 fpm NA

0.045 88.8 50.6 0.13 @ 369 fpm 0.09 @ 369 fpm 0.11 at 504 fpm

0.052 87.3 46.4

0.060 86.1 42.2

0.070 84.1 38.0

0.081 83.1 39.5

0.093 80.6 31.1

0.11 80.0 35.6

0.12 78.4 33.5

0.14 76.9 28.4

0.17 74.5 30.7

0.19 74.3 32.0

0.22 73.9 31.4

0.26 72.9 32.4

0.29 72.5 23.5

0.30 – 0.40 73.9 28.2

0.40 – 0.55 80.3 31.7

0.55 – 0.70 85.7 35.5

0.70 – 1.00 90.0 37.7

1.00 – 1.30 93.7 39.7

1.30 – 1.60 95.0 42.3

1.60 – 2.20 96.0 45.1

2.20 – 3.00 96.8 47.2

3.00 – 4.00 96.9 47.9

4.00 – 5.50 97.4 52.2

5.50 – 7.00 97.0 51.5

7.00 – 10.00 96.4 NA

E1 (0.30 – 1.0) 82.5 33.3

E2 (1.0 – 3.0) 95.3 43.6

E3 (3.0 – 10.0) 96.9 50.5

MERV rating from vendor NA NA

MERV rating from testing 14 7
H-12

This page intentionally left blank.
I-1

Appendix I

Quality Assurance

Work under this task was completed in accordance with a 

pair of EPA approved quality assurance test plans (QAPPs) 

entitled “Research on Air Cleaning and HVAC Systems for 

Protecting Buildings from Terrorist Attacks; Test/Quality 

Assurance Plan for Task 2: Development of Performance 

Information for Common Ventilation Filters,” and “Research 

on Air Cleaning and HVAC Systems for Protecting Buildings 

from Terrorist Attacks; Test/Quality Assurance Plan for Task 

3: Development of Performance Information for Electronic 

Air Cleaners.” These two QAPPs described the development 

of the filter and electronic air cleaner tests matrices, sample 

acquisition and handling procedures, the inert aerosol and 

bioaerosol test procedures, the aging and conditioning 

test procedures, and the data analysis procedures. The text 

from the two relevant QAPPs was included in the relevant 

portions of this draft final comprehensive report. For 

example, development of the test matrices was described in 

Section 2. The inert aerosol and bioaerosol test procedures 

were described in Sections 3.1.1 and 3.2.1, respectively. The 

inert aerosol and bioaerosol data analysis procedures were 

described in Sections 3.1.2 and 3.2.2, respectively. Sample 

acquisition and handling, as well as the various aging and 

conditioning procedures were described in Sections 3.3, 3.4, 

and 3.5.

In accordance with the QAPPs, an external quality assurance 

(QA) audit of Tasks 2/3 was performed by an EPA staff 

member and a designated representative on 9 August 2006 at 

Battelle’s Columbus facility. The quality assurance inspectors 

reviewed the sample handling logs, standard operating 

procedures, test record sheets, instrument calibration sheets, 

data logs and data sheets from the inert and bioaerosol 

tests, and various other documentation. In addition, the 

quality assurance inspectors witnessed the performance 

of a bioaerosol test. Official documentation from the QA 

inspectors was received on 8 September 2006. In general, 

the auditors were pleased with the conduct of the work and 

had no significant findings that affected the execution of 

tests. A final memo was sent on 6 October 2006 in response 

to the findings of the auditors. No corrective actions were 

deemed necessary. At the completion of Tasks 2/3, all quality 

objectives had been achieved. 

In general, the required QA calculations can be found 

throughout the body of this report or in the attached data 

CD. Three QA calculations that cannot be found in their 

entirety elsewhere in this report are provided below. First, 

as described in Section 3.2.1, for the bioaerosol tests, it 

was required that the air velocity uniformity and bioaerosol 

concentration uniformity in the text duct possess coefficients 

of variance of less than 25% and 30%, respectively. Table I-1 

demonstrates a sample calculation showing that the air 

velocity unformity CV was within 25%. Tables I-2 and I-3 

demonstrate a sample calculation showing that the aerosol 

concentration CVs were less than 25% at both the upstream 

and downstream sampling locations. In addition, it was 

required that the downstream and upstream bioaerosol 

mean concentrations agree within 20%. Using the ratio of 

the overall averages from Tables I-2 and I-3, it can be seen 

that the mean concentrations agreed to were within 0.5%. 

Lastly, for the non-standard portion of the inert aerosol tests 

(0.03 to 0.3 μm particle size), it was required that the aerosol 

concentration uniformity of the test duct possess a coefficient 

of variance of less than 15%. Tables I-4 and I-5 demonstrate 

the results from measurements of the aerosol concentration 

uniformity with no filter present. As shown in Tables I-4 and 

I-5, the results indicated that the aerosol uniformity met the 

requirement of a CV of less than 15% for all particle size 

ranges at both test velocities.

Table I-1. Air Velocity Uniformity of the Bioaerosol

Test Rig average = 210 fpm, CV = 43 fpm or 

20.5%)

Air Velocity (feet per minute)

192 239 135

262 268 218

209 209 162

Table I-2. Upstream Bioaerosol Concentration 

Uniformity of the Bioaerosol Test Rig

(average = 5,240 CFU/L, CV = 527 CFU/L

or 10.1%)

Concentration (CFU/L of air)

5,761 4,719 4,699

5,678 4,564 4,956

5,628 5,203 5,951

Table I-3. Downstream Bioaerosol Concentration 

Uniformity of the Bioaerosol Test Rig

(average = 5,214 CFU/L, CV = 373 CFU/L

or 7.2%)

Concentration (CFU/L)

5,367 5,332 4,840

5,220 5,328 4,442

5,210 5,737 5,451
I-2

Table I-4. Results from the Aerosol Concentration Uniformity Evaluations of Intertek’s ASHRAE 52.2-1999

Test Stand at 472 CFM

Average Size (μm)

0.0255 0.0294 0.0340 0.0392 0.0453 0.0523 0.0604 0.0698 0.0806 0.0931 0.107 0.124 0.143 0.165 0.191 0.221 0.255 0.294 0.340 0.392

Grid Point Total Particles Counted1 1569 2061 2648 3135 3611 3930 4169 4201 4247 3968 3582 3185 2721 2284 1778 1411 1064 780 607 4462 1675 2129 2823 3272 3773 4090 4287 4511 4362 4118 3747 3336 2798 2337 1875 1468 1094 865 640 4993 2268 2590 3060 3515 3968 4252 4571 4589 4502 4254 3927 3459 2980 2395 1911 1560 1218 897 677 5394 2057 2383 2878 3359 3729 4132 4398 4336 4344 4106 3746 3334 2804 2348 1884 1495 1131 846 622 5085 1609 2034 2602 3213 3707 4126 4380 4395 4463 4236 3889 3366 2945 2433 1914 1521 1210 906 658 5206 1951 2399 3038 3674 4131 4466 4636 4761 4582 4414 4051 3555 3026 2539 1987 1525 1194 935 700 5477 1946 2480 3058 3667 3962 4160 4456 4400 4419 4094 3831 3451 2905 2444 1913 1529 1195 905 698 5198 1715 2173 2878 3412 3855 4232 4424 4432 4520 4165 3909 3357 2891 2435 1956 1533 1147 877 692 5139 1784 2258 2836 3354 3884 4342 4585 4536 4499 4365 3977 3530 3126 2508 2025 1583 1249 958 696 519Mean 1842 2278 2869 3400 3847 4192 4434 4462 4437 4191 3851 3397 2911 2414 1916 1514 1167 885 666 512St. Dev 231 195 167 189 160 154 150 161 104 141 142 114 126 82 71 51 62 52 35 29CV 12.5% 8.6% 5.8% 5.5% 4.2% 3.7% 3.4% 3.6% 2.4% 3.4% 3.7% 3.4% 4.3% 3.4% 3.7% 3.4% 5.3% 5.9% 5.3% 5.6%

Table I-5. Results from the Aerosol Concentration Uniformity Evaluations of Intertek’s ASHRAE 52.2-1999 

Test Stand at 1968 CFM

Average Size (μm)

0.0255 0.0294 0.0340 0.0392 0.0453 0.0523 0.0604 0.0698 0.0806 0.0931 0.107 0.124 0.143 0.165 0.191 0.221 0.255 0.294 0.340 0.392

Grid Point Total Particles Counted1 327 448 544 673 710 819 855 880 866 823 737 650 527 442 369 288 218 170 128 1052 399 505 612 692 836 840 928 942 916 882 783 721 575 483 392 306 230 184 137 963 421 515 634 785 883 922 949 1040 958 857 850 737 619 480 414 299 227 180 137 854 327 509 611 728 784 842 870 876 866 826 763 678 558 474 380 296 221 178 113 905 337 463 611 724 849 892 958 927 927 880 808 696 588 499 405 311 243 191 127 886 412 532 658 762 889 935 1028 1006 998 915 795 748 643 527 422 344 237 197 140 1137 315 448 529 652 768 829 945 895 897 873 752 652 550 440 372 292 231 166 129 1028 408 523 578 707 811 863 956 928 926 875 769 706 614 506 397 310 248 204 149 1039 360 522 642 769 850 972 964 947 944 939 838 732 597 537 414 326 248 178 158 105Mean 367 496 602 721 820 879 939 938 922 875 788 702 586 487 396 308 234 183 136 99St. Dev 43 34 44 45 58 54 52 55 43 37 38 36 37 34 19 18 11 12 13 9CV 11.6% 6.8% 7.3% 6.3% 7.1% 6.1% 5.5% 5.9% 4.7% 4.3% 4.8% 5.1% 6.3% 6.9% 4.9% 5.8% 4.7% 6.7% 9.6% 9.5%
I-3
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