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Bibliometric Analysis for Papers on Topics Related to Particulate Matter (PM)
March 21, 2005

This is a bibliometric analysis of the papers prepared by intramural and extramural researchers of the U.S. Environmental Protection Agency (EPA) on topics related to particulate matter (PM). For this analysis, 904 papers were reviewed. These 904 papers, published from 1998 to 2005, were cited 9,578 times in the journals covered by Thomson’s Web of Science1. Of these 904 papers, 723 (80%) have been cited at least once in a journal.

The analysis was completed using Thomson’s Essential Science Indicators (ESI) and Journal Citation Reports (JCR) as benchmarks. ESI provides access to a unique and comprehensive compilation of essential science performance statistics and science trends data derived from Thomson’s databases. The chief indicators of output, or productivity, are journal article publication counts. For influence and impact measures, ESI employs both total citation counts and cites per paper scores. The former reveals gross influence while the latter shows weighted influence, also called impact. JCR presents quantifiable statistical data that provide a systematic, objective way to evaluate the world’s leading journals and their impact and influence in the global research community.

Summary of Analysis

More than one-third of the PM publications are highly cited papers. A review of the citations indicates that 321 (35.5%) of the PM papers qualify as highly cited when using the ESI criteria for the top 10% of highly cited publications. Seventy-four (8.2%) of the PM papers qualify as highly cited when using the criteria for the top 1%. Thirteen (1.4%) of these papers qualify as very highly cited (in the top 0.1%), and two papers actually meet the top 0.01% threshold.

The PM papers are more highly cited than the average paper. Using the ESI average citation rates for papers published by field as the benchmark, in 10 of the 12 fields in which the EPA PM papers were published, the ratio of actual to expected cites is greater than 1, indicating that the PM papers are more highly cited than the average papers in those fields.

Nearly one-third of the PM papers are published in very high impact journals. Two-hundred fifty-four (254) of 904 papers were published in the top 10% of journals ranked by JCR Impact Factor, representing 28% of EPA’s PM papers. Nearly one-third of the PM papers are published in the top 10% of journals ranked by JCR Immediacy Factor. Two-hundred sixty-seven (267) of the 904 papers appear in the top 10% of journals, representing 29.5% of EPA’s PM papers.

Twenty-three of the PM papers qualify as hot papers. Using the hot paper thresholds established by ESI as a benchmark, 23 hot papers, representing 2.5% of the PM papers, were identified in the analysis.

The author self-citation rate is below average. Five hundred thirty-seven (537) of the 9,578 cites are author self-cites. This 5.6% author self-citation rate is below the accepted range of 10-30% author self-citation rate.

Highly Cited PM Publications

The 904 PM papers reviewed for this analysis covered 12 of the 22 ESI fields. The distribution of the papers among these 12 fields and the number of citations by field are presented in Table 1.

Table 1. PM Papers by ESI Fields

No. of Citations

ESI Field

No. of EPA PM Papers

Average Cites/Paper

2,674

Environment/Ecology

263

10.17

2,067

Engineering

236

8.76

1,432

Pharmacology & Toxicology

146

9.81

872

Biology & Biochemistry

68

12.49

859

Clinical Medicine

42

20.45

823

Multidisciplinary

66

12.47

368

Molecular Biology & Genetics

19

19.37

295

Chemistry

35

8.43

144

Immunology

13

11.08

23

Neuroscience & Behavior

1

23.00

11

Physics

8

1.38

10

Mathematics

7

1.43

Total = 9,578

 

Total = 904

 

There were 321 (35.5% of the papers analyzed) highly cited EPA PM papers in 10 of the 12 fields—Environment/Ecology, Engineering, Pharmacology & Toxicology, Clinical Medicine, Multidisciplinary, Biology & Biochemistry, Chemistry, Molecular Biology & Genetics, Immunology, and Mathematics—when using the ESI criteria for the top 10% of papers. Table 2 shows the number of EPA papers in those 10 fields that met the top 10% threshold in ESI. Seventy-four (8.2%) of the papers analyzed qualified as highly cited when using the ESI criteria for the top 1% of papers. These papers covered five fields—Environment/Ecology, Engineering, Clinical Medicine, Biology & Biochemistry, and Multidisciplinary. Table 3 shows the 74 papers by field that met the top 1% threshold in ESI. There were 13 very highly cited EPA PM papers in three fields—Engineering, Environment/Ecology, and Clinical Medicine. These 13 papers met the top 0.1% threshold in ESI (1.4% of the papers analyzed). Two of these 13 PM papers actually met the top 0.01% threshold in ESI (i.e., the two papers by Drewnick).

Table 2. Number of Highly Cited PM Papers by Field (top 10%)

Citations

ESI Field

No. of Papers

Average Cites/Paper

% of EPA Papers in Field

2,073

Environment/Ecology

106

19.56

40.3%

1,863

Engineering

123

15.15

52.12%

873

Pharmacology & Toxicology

30

29.10

20.55%

757

Clinical Medicine

14

54.07

33.33%

632

Multidisciplinary

23

27.48

34.85%

395

Biology & Biochemistry

9

43.89

13.24%

182

Chemistry

9

20.22

25.71%

134

Molecular Biology & Genetics

2

67.00

10.53%

119

Immunology

3

39.67

23.08%

5

Mathematics

2

2.50

28.57%

Table 3. Number of Highly Cited PM Papers by Field (top 1%)

Citations

ESI Field

No. of Papers

Average Cites/Paper

% of EPA Papers in Field

1,206

Engineering

50

24.12

21.19%

778

Environment/Ecology

18

43.22

6.84%

399

Clinical Medicine

2

199.5

4.76%

226

Biology & Biochemistry

3

75.33

4.35%

88

Multidisciplinary

1

88.00

1.52%

The citations for the highly cited papers in the top 1% are presented in Tables 4 through 8. The citations for the very highly cited papers are listed in Table 9.

Table 4. Highly Cited PM Papers in the Field of Engineering(top 1%)

No. of Cites

First Author

Paper

79

Yu JZ

Identification of products containing -COOH, -OH, and -C=O in atmospheric oxidation of hydrocarbons. Environmental Science & Technology 1998;32(16):2357-2370.

33

Kleeman MJ

Source contributions to the size and composition distribution of atmospheric particles: Southern California in September1996. Environmental Science & Technology 1999;33(23):4331-4341.

33

Zhang Y

Simulation of aerosol dynamics: A comparative review of algorithms used in air quality models. Aerosol Science and Technology 1999;31(6):487-514.

37

Hughes LS

Size and composition distribution of atmospheric particles in southern California. Environmental Science & Technology 1999;33(20):3506-3515.

25

Mallina RV

High speed particle beam generation: A dynamic focusing mechanism for selecting ultrafine particles, Aerosol Science and Technology 2000;33(1-2):87-104.

26

Christoforou CS

Trends in fine particle concentration and chemical composition in Southern California. Journal of the Air & Waste Management Association 2000;50(1):43-53.

29

Hughes LS

Evolution of atmospheric particles along trajectories crossing the Los Angeles basin. Environmental Science & Technology 2000;34(15):3058-3068.

32

Ansari AS

Water absorption by secondary organic aerosol and its effect an inorganic aerosol behavior. Environmental Science & Technology 2000;34(1):71-77.

33

Tobias HJ

Thermal desorption mass spectrometric analysis of organic aerosol formed from reactions of 1-tetradecene and O-3 in the presence of alcohols and carboxylic acids. Environmental Science & Technology 2000;34(11):2105-2115.

37

Allen JO

Particle detection efficiencies of aerosol time of flight mass spectrometers under ambient sampling conditions. Environmental Science & Technology 2000;34(1):211-217.

40

Long CM

Characterization of indoor particle sources using continuous mass and size monitors. Journal of the Air & Waste Management Association 2000;50(7):1236-1250.

40

Sarnat JA

Assessing the relationship between personal particulate and gaseous exposures of senior citizens living in Baltimore, MD. Journal of the Air & Waste Management Association 2000;50(7):1184-1198.

43

Stolzenburg MR

Method for the automated measurement of fine particle nitrate in the atmosphere. Environmental Science & Technology 2000;34(5):907-914.

75

Jayne JT

Development of an aerosol mass spectrometer for size and composition analysis of submicron particles. Aerosol Science and Technology 2000;33(1-2):49-70.

19

Vette AF

Characterization of indoor-outdoor aerosol concentration relationships during the Fresno PM exposure studies. Aerosol Science and Technology 2001;34(1):118-126.

21

Mosley RB

Penetration of ambient fine particles into the indoor environment. Aerosol Science and Technology 2001;34(1):127-136.

23

Tolocka MP

East versus West in the US: Chemical characteristics of PM2.5 during the winter of 1999. Aerosol Science and Technology 2001;34(1):88-96.

24

Seinfeld JH

Modeling the formation of secondary organic aerosol (SOA). 2. The predicted effects of relative humidity on aerosol formation in the alpha-pinene-, beta-pinene-, sabinene-, Delta(3)-Carene-, and cyclohexene-ozone systems. Environmental Science & Technology 2001;35(9):1806-1817.

26

Pankow JF

Modeling the formation of secondary organic aerosol. 1. Application of theoretical principles to measurements obtained in the alpha-pinene/, beta- pinene/, sabinene/, Delta(3)-carene/, and cyclohexene/ozone systems. Environmental Science & Technology 2001;35(6):1164-1172.

29

Fine PM

Chemical characterization of fine particle emissions from fireplace combustion of woods grown in the northeastern United States. Environmental Science & Technology 2001;35(13):2665-2675.

31

Lewtas J

Comparison of sampling methods for semi-volatile organic carbon associated with PM 2.5. Aerosol Science and Technology 2001;34 (1):9-22.

31

Kamens RM

Modeling aerosol formation from alpha-pinene plus NO x in the presence of natural sunlight using gas-phase kinetics and gas-particle partitioning theory. Environmental Science & Technology 2001;35 (7):1394-1405.

33

Jang MS

Atmospheric secondary aerosol formation by heterogeneous reactions of aldehydes in the presence of a sulfuric acid aerosol catalyst. Environmental Science & Technology 2001;35(24):4758-4766.

34

Long CM

Using time- and size-resolved particulate data to quantify indoor penetration and deposition behavior. Environmental Science & Technology 2001;35(10):2089-2099.

50

Woo KS

Measurement of Atlanta aerosol size distributions: Observations of ultrafine particle events. Aerosol Science and Technology 2001;34(1):75-87.

56

Weber RJ

A particle-into-liquid collector for rapid measurement of aerosol bulk chemical composition. Aerosol Science and Technology 2001;35(3):718-727.

12

Hays MD

Speciation of gas-phase and fine particle emissions from burning of foliar fuels. Environmental Science & Technology 2002;36(11):2281-2295.

13

Frey HC

Quantification of variability and uncertainty in lawn and garden equipment NOx and total hydrocarbon emission factors. Journal of the Air & Waste Management Association 2002;52(4):435-448.

13

Kim S

Size distribution and diurnal and seasonal trends of ultrafine particles in source and receptor sites of the Los Angeles basin. Journal of the Air & Waste Management Association 2002;52(3):297-307.

14

Zhang XF

A numerical characterization of particle beam collimation by an aerodynamic lens-nozzle system: Part I. An individual lens or nozzle. Aerosol Science and Technology 2002;36(5):617-631.

14

Lim HJ

Origins of primary and secondary organic aerosol in Atlanta: Results' of time-resolved measurements during the Atlanta Supersite experiment. Environmental Science & Technology 2002;36(21):4489-4496.

15

Phares DJ

Performance of a single ultrafine particle mass spectrometer. Aerosol Science and Technology 2002;36(5):583-592.

28

McMurry PH

The relationship between mass and mobility for atmospheric particles: A new technique for measuring particle density. Aerosol Science and Technology 2002;36(2):227-238.

35

Zhu YF

Concentration and size distribution of ultrafine particles near a major highway. Journal of the Air & Waste Management Association 2002;52(9):1032-1042.

7

Maykut NN

Source apportionment of PM 2.5 at an urban IMPROVE site in Seattle, Washington. Environmental Science & Technology 2003;37(22):5135-5142.

8

Lake DA

Mass spectrometry of individual particles between 50 and 750 nm in diameter at the Baltimore Supersite. Environmental Science & Technology 2003;37(15):3268-3274.

9

Jang MS

Particle growth by acid-catalyzed heterogeneous reactions of organic carbonyls on preexisting aerosols.

12

Offenberg JH

Persistent organic pollutants in the dusts that settled across lower Manhattan after September 11, 2001. Environmental Science & Technology 2003;37(3):502-508.

12

Lewis CW

Source apportionment of phoenix PM2.5 aerosol with the Unmix receptor model. Journal of the Air & Waste Management Association 2003;53(3):325-338.

20

Park K

Relationship between particle mass and mobility for diesel exhaust particles. Environmental Science & Technology 2003;37(3):577-583.

3

Stanier CO

A method for the in situ measurement of fine aerosol water content of ambient aerosols: The dry-ambient aerosol size spectrometer (DAASS). Aerosol Science and Technology 2004;38(Suppl 1):215-228.

6

Stanier CO

Nucleation events during the Pittsburgh air quality study: Description and relation to key meteorological, gas phase, and aerosol parameters. Aerosol Science and Technology 2004;38(Suppl 1):253-264.

3

Huggins FE

Quantifying hazardous species in particulate matter derived from fossil-fuel. Environmental Science & Technology 2004;38(6):1836-1842.

3

Kim E

Analysis of ambient particle size distributions using unmix and positive matrix factorization. Environmental Science & Technology 2004;38(1):202-209.

3

Keywood MD

Secondary organic aerosol formation from cyclohexene ozonolysis: Effect of OH scavenger and the role of radical chemistry. Environmental Science & Technology 2004;38(12):3343-3350.

7

Cho AK

Determination of four quinones in diesel exhaust particles, SRM 1649a, an atmospheric PM 2.5. Aerosol Science and Technology 2004;38(Suppl 1):68-81.

5

Canagaratna MR

Chase studies of particulate emissions from in-use New York City vehicles. Aerosol Science and Technology 2004;38(6):555-573.

6

Hogrefe O

Development, operation and applications of an aerosol generation, calibration and research facility. Aerosol Science and Technology 2004;38(Suppl 1):196-214.

8

Drewnick F

Measurement of ambient aerosol composition during the PMTACS-NY 2001 using an aerosol mass spectrometer. Part II: Chemically speciated mass distributions. Aerosol Science and Technology 2004;38(Suppl 1):104-117.

11

Drewnick F

Measurement of ambient aerosol composition during the PMTACS-NY 2001 using an aerosol mass spectrometer. Part I: Mass concentrations. Aerosol Science and Technology 2004;38 (Suppl 1):92-103.

Table 5. Highly Cited PM Papers in the Field of Environment/Ecology (top 1%)

No. of Cites

First Author

Paper

92

Simoneit BRT

Levoglucosan, a tracer for cellulose in biomass burning and atmospheric particles. Atmospheric Environment 1999;33(2):173-182.

97

Yu JZ

Gas-phase ozone oxidation of monoterpenes: Gaseous and particulate products. Journal of Atmospheric Chemistry 1999;34(2):207-258.

110

Liao DP

Daily variation of particulate air pollution and poor cardiac autonomic control in the elderly. Environmental Health Perspectives 1999;107(7):521-525.

74

Schwartz J

Fine particles are more strongly associated than coarse particles with acute respiratory health effects in schoolchildren. Epidemiology 2000;11(1):6-10.

96

Laden F

Association of fine particulate matter from different sources with daily mortality in six US cities. Environmental Health Perspectives 2000;108(10):941-947.

43

Dockery DW

Epidemiologic evidence of cardiovascular effects of particulate air pollution. Environmental Health Perspectives 2001;109(Suppl 4):483-486.

69

Oberdorster G

Pulmonary effects of inhaled ultrafine particles. International Archives of Occupational and Environmental Health 2001;74 (1):1-8.

26

Zanobetti A

The temporal pattern of mortality responses to air pollution: A multicity assessment of mortality. Epidemiology 2002;13(1):87-93.

32

Zhu YF

Study of ultrafine particles near a major highway with heavy-duty diesel traffic. Atmospheric Environment 2002;36(27):4323-4335.

32

Lioy PJ

Characterization of the dust/smoke aerosol that settled east of the World Trade Center (WTC) in Lower Manhattan after the collapse of the WTC 11 September 2001. Environmental Health Perspectives 2002;110(7):703-714.

11

Drewnick F

Intercomparison and evaluation of four semi-continuous PM 2.5 sulfate instruments. Atmospheric Environment 2003;37(24):3335-3350.

11

Jang M

Organic aerosol growth by acid-catalyzed heterogeneous reactions of octanal in a flow reactor. Atmospheric Environment 2003;37(15):2125-2138.

11

McGee JK

Chemical analysis of World Trade Center fine particulate matter for use in toxicologic assessment. Environmental Health Perspectives 2003;111(7):972-980.

21

Orsini DA

Refinements to the particle-into-liquid sampler (PILS) for ground and airborne measurements of water soluble aerosol composition. Atmospheric Environment 2003;37(9-10):1243-1259.

41

Li N

Ultrafine particulate pollutants induce oxidative stress and mitochondrial damage. Environmental Health Perspectives 2003;111(4):455-460.

4

DeMarini DM

Bioassay-directed fractionation and Salmonella mutagenicity of automobile and forklift diesel exhaust particles. Environmental Health Perspectives 2004;112(8):814-819.

4

Landrigan PJ

Health and environmental consequences of the World Trade Center disaster. Environmental Health Perspectives 2004;112(6):731-739.

4

Singh P

Sample characterization of automobile and forklift diesel exhaust particles and comparative pulmonary toxicity in mice. Environmental Health Perspectives 2004;112(8):820-825.

Table 6. Highly Cited PM Papers in the Field of Clinical Medicine (top 1%)

No. of Cites

First Author

Paper

124

Abbey DE

Long-term inhalable particles and other air pollutants related to mortality in nonsmokers. American Journal of Respiratory and Critical Care Medicine 1999;159(2):373-382.

275

Pope CA

Lung cancer, cardiopulmonary mortality, and long-term exposure to fine particulate air pollution. JAMA-Journal of the American Medical Association 2002;287(9):1132-1141.

Table 7. Highly Cited PM Papers in the Field of Biology & Biochemistry (top 1%)

No. of Cites

First Author

Paper

6

Pope CA

Cardiovascular mortality and long-term exposure to particulate air pollution–epidemiological evidence of general pathophysiological pathways of disease.Circulation 2004;109(1):71-77.

96

Peters A

Increased particulate air pollution and the triggering of myocardial infarction.Circulation 2001;103(23):2810-2815.

124

Gold DR

Ambient pollution and heart rate variability.Circulation 2000;101(11):1267-1273.

Table 8. Highly Cited PM Papers in the Field of Multidisciplinary (top 1%)

No. of Cites

First Author

Paper

88

Gard EE

Direct observation of heterogeneous chemistry in the atmosphere.Science 1998;279(5354):1184-1187.

Table 9. Very Highly Cited PM Papers (Top 0.1%)

Field

No. of Cites

First Author

Paper

Clinical Medicine

275

Pope CA

Lung cancer, cardiopulmonary mortality, and long-term exposure to fine particulate air pollution. JAMA-Journal of the American Medical Association 2002;287(9):1132-1141.

Engineering

75

Jayne JT

Development of an aerosol mass spectrometer for size and composition analysis of submicron particles. Aerosol Science and Technology 2000;33(1-2):49-70.

 

50

Woo KS

Measurement of Atlanta aerosol size distributions: Observations of ultrafine particle events. Aerosol Science and Technology 2001;34(1):75-87.

 

56

Weber RJ

A particle-into-liquid collector for rapid measurement of aerosol bulk chemical composition. Aerosol Science and Technology 2001;35(3):718-727.

 

35

Zhu YF

Concentration and size distribution of ultrafine particles near a major highway. Journal of the Air & Waste Management Association 2002;52(9):1032-1042.

 

20

Park K

Relationship between particle mass and mobility for diesel exhaust particles. Environmental Science & Technology 2003;37(3):577-583.

Engineering

11

Drewnick

Measurement of ambient aerosol composition during the PMTACS-NY 2001 using an aerosol mass spectrometer. Part I: Mass concentrations. Aerosol Science and Technology 2004;38 (Suppl 1):92-103.

 

8

Drewnick

Measurement of ambient aerosol composition during the PMTACS-NY 2001 using an aerosol mass spectrometer. Part II: Chemically speciated mass distributions. Aerosol Science and Technology 2004;38(Suppl 1):104-117.

 

7

Cho AK

Determination of four quinones in diesel exhaust particles, SRM 1649a, an atmospheric PM 2.5. Aerosol Science and Technology 2004;38(Suppl 1):68-81.

 

6

Hogrefe O

Development, operation and applications of an aerosol generation, calibration and research facility. Aerosol Science and Technology 2004;38(Suppl 1):196-214.

 

6

Stanier CO

Nucleation events during the Pittsburgh air quality study: Description and relation to key meteorological, gas phase, and aerosol parameters. Aerosol Science and Technology 2004;38(Suppl 1):253-264.

 

5

Canagaratna MR

Chase studies of particulate emissions from in-use New York City vehicles. Aerosol Science and Technology 2004;38(6):555-573.

Environment/

Ecology

41

Li N

Ultrafine particulate pollutants induce oxidative stress and mitochondrial damage. Environmental Health Perspectives 2003;111(4):455-460.

Ratio of Actual Cites to Expected Citation Rates

The expected citation rate is the average number of cites that a paper published in the same journal in the same year and of the same document type (article, review, editorial, etc.) has received from the year of publication to the present. Using the ESI average citation rates for papers published by field as the benchmark, in 10 of the 12 fields in which the EPA PM papers were published, the ratio of actual to expected cites is greater than 1, indicating that the EPA papers are more highly cited than the average papers in those fields (see Table 10).

Table 10. Ratio of Average Cites to Expected Cites for PM Papers by Field

ESI Field

Total Cites

Expected Cite Rate

Ratio

Biology & Biochemistry

872

787.66

1.11

Chemistry

295

211.66

1.39

Clinical Medicine

859

226.30

3.80

Engineering

2,067

378.11

5.45

Environment/Ecology

2,674

966.32

2.77

Immunology

144

103.38

1.39

Mathematics

10

6.34

1.58

Molecular Biology & Genetics

368

374.93

0.98

Multidisciplinary

823

268.71

3.06

Neuroscience & Behavior

23

18.39

1.25

Pharmacology & Toxicology

1,432

841.16

1.70

Physics

11

37.85

0.29

JCR Benchmarks

The Impact Factor is a well known metric in citation analysis. It is a measure of the frequency with which the average article in a journal has been cited in a particular year. The Impact Factor helps evaluate a journal’s relative importance, especially when compared to others in the same field. The Impact Factor is calculated by dividing the number of citations in the current year to articles published in the 2 previous years by the total number of articles published in the 2 previous years.

Table 11 indicates the number of PM papers published in the top 10% of journals, based on the JCR Impact Factor. Two-hundred fifty-four (254) of 904 papers were published in the top 10% of journals, representing 28% of EPA’s PM papers.

Table 11. PM Papers in Top 10% of Journals by JCR Impact Factor

EPA PM Papers in that Journal

Journal

Impact Factor

(IF)

JCR IF Rank

64

Environmental Health Perspectives

3.408

538

62

Environmental Science & Technology

3.592

487

26

American Journal of Physiology-Lung Cellular and Molecular Physiology

3.735

435

20

Epidemiology

4.220

350

17

American Journal of Respiratory and Critical Care Medicine

8.876

100

17

American Journal of Respiratory Cell and Molecular Biology

4.015

380

7

Analytical Chemistry

5.250

248

5

Circulation

11.164

72

4

Journal of Biological Chemistry

6.482

179

4

Journal of Immunology

6.702

167

3

Science

29.781

11

3

Free Radical Biology and Medicine

5.063

260

3

American Journal of Epidemiology

4.486

310

3

Thorax

4.188

356

2

Lancet

18.316

28

2

Chest

3.264

585

2

Chemical Research in Toxicology

3.332

555

1

New England Journal of Medicine

34.833

5

1

JAMA-Journal of the American Medical Association

21.455

22

1

Journal of Clinical Investigation

14.307

44

1

Proceedings of the National Academy of Sciences

10.272

81

1

Cancer Research

8.649

105

1

FASEB Journal

7.172

149

1

Journal of Allergy and Clinical Immunology

6.831

162

1

Advanced Drug Delivery Reviews

6.588

170

1

Critical Care Medicine

4.195

353

1

Journal of Leukocyte Biology

4.180

357

Total = 254

     

Immediacy Index

The journal Immediacy Index is a measure of how quickly the average article in a journal is cited. It indicates how often articles published in a journal are cited within the year they are published. The Immediacy Index is calculated by dividing the number of citations to articles published in a given year by the number of articles published in that year.

Table 12 indicates the number of EPA papers published in the top 10% of journals, based on the JCR Immediacy Index. Two-hundred sixty-seven (267) of the 904 papers appear in the top 10% of journals, representing 29.5% of EPA’s PM papers.

Table 12. PM Papers in Top 10% of Journals by JCR Immediacy Index

EPA Papers in that Journal

Journal

Immediacy Index

(II)

JCR II Rank

64

Environmental Health Perspectives

0.869

304

52

Journal of Geophysical Research - Atmospheres

0.827

334

26

American Journal of Physiology-Lung Cellular and Molecular Physiology

0.654

496

20

Epidemiology

0.938

264

19

Journal of Aerosol Science

0.686

462

17

American Journal of Respiratory Cell and Molecular Biology

0.623

546

17

American Journal of Respiratory and Critical Care Medicine

2.461

56

7

Analytical Chemistry

0.657

493

5

Circulation

1.946

82

4

Journal of Immunology

0.988

239

4

Philosophical Transactions of the Royal Society of London Series A-Mathematical Physical and Engineering Sciences

0.867

305

4

Journal of Biological Chemistry

1.231

160

3

American Journal of Epidemiology

0.908

281

3

Free Radical Biology and Medicine

0.712

432

3

Thorax

1.237

158

3

Science

5.589

12

2

Biometals

0.717

424

2

Lancet

5.826

10

1

Journal of Chemical Physics

0.661

487

1

Journal of Clinical Investigation

2.946

41

1

Critical Care Medicine

1.103

192

1

Journal of Allergy and Clinical Immunology

1.465

123

1

Journal of Leukocyte Biology

0.671

473

1

Cancer Research

0.935

268

1

FASEB Journal

1.247

154

1

New England Journal of Medicine

11.719

2

1

Advanced Drug Delivery Reviews

0.805

352

1

Proceedings of the National Academy of Sciences

1.935

83

1

American Journal of Industrial Medicine

0.616

552

1

JAMA-Journal of the American Medical Association

6.048

9

Total = 267

     

Hot Papers

ESI establishes citation thresholds for hot papers, which are selected from the highly cited papers in different fields, but the time frame for citing and cited papers is much shorter—papers must be cited within 2 years of publication and the citations must occur in a 2-month time period. Papers are assigned to 2-month periods and thresholds are set for each period and field to select 0.1% of papers. There were no hot papers identified for the current 2-month period (i.e., January-February 2005), but there were a number of hot papers identified from previous periods.

Using the hot paper thresholds established by ESI as a benchmark, 23 hot papers, representing 2.5% of the PM papers, were identified in four fields—Biology & Biochemistry, Clinical Medicine, Environment/Ecology, and Engineering. The hot papers are listed in Table 13.

Table 13. Hot Papers Identified Using ESI Thresholds

Field

ESI Hot Papers Threshold

No. of Cites in 2-Month Period

Paper

Biology & Biochemistry

10

11 cites in July-August 2001

Gold DR, et al. Ambient pollution and heart rate variability. Circulation 2000;101(11):1267-1273.

Clinical Medicine

12

15 cites in November-December 2003

Pope CA, et al. Lung cancer, cardiopulmonary mortality, and long-term exposure to fine particulate air pollution. JAMA–Journal of the American Medical Association 2002;287(9):1132-1141.

Environment/Ecology

8

9 cites in May-June 2004

Li N, et al. Ultrafine particle pollutants induce oxidative stress and mitochondrial damage. Environmental Health Perspectives 2003;111(4):455-460.

   

10 cites in June-July 2004

Orsini DA, et al. Refinements to the particle-into-liquid sampler (PILS) for ground and airborne measurements of water soluble aerosol composition. Atmospheric Environment 2003;37(9-10):1243-1259.

   

9 cites in April-May 2004

Lioy PJ, et al. Characterization of the dust/smoke aerosol that settled east of the World Trade Center (WTC) in Lower Manhattan after the collapse of the WTC 11 September 2001. Environmental Health Perspectives 2002;110(7):703-714.

   

9 cites in September-October 2002

Laden F, et al. Association of fine particulate matter from different sources with daily mortality in six US cities. Environmental Health Perspectives 2000;108(10):941-947.

Engineering

4

4 cites in May-June 2002

Hughes LS, et al. Evolution of atmospheric particles along trajectories crossing the Los Angeles basin. Environmental Science & Technology 2000;34(15):3058-3068.

Engineering

4

4 cites in November-December 2001

Ansari AS, Pandis SN. Water absorption by secondary organic aerosol and its effect on inorganic aerosol behavior. Environmental Science & Technology 2000;34(1):71-77.

   

4 cites in July 2002

Long CM, et al. Characterization of indoor particle sources using continuous mass and size monitors. Journal of the Air & Waste Management Association 2000;50(7):1236-1250.

   

4 cites in May-June 2002

Jayne JT, et al. Development of an aerosol mass spectrometer for size and composition analysis of submicron particles. Aerosol Science & Technology 2000;33(1-2):49-70.

   

4 cites in December 2002-January 2003

Fine PM, et al. Chemical characterization of fine particle emissions from fireplace combustion of woods grown in the northeastern United States. Environmental Science & Technology 2001;35(13):2665-2675.

   

5 cites in September-October 2003

Jang MS, Kamens RM. Atmospheric secondary aerosol formation by heterogeneous reactions of aldehydes in the presence of a sulfuric acid aerosol catalyst. Environmental Science & Technology 2001;35(24):4758:4766.

   

4 cites in June-July 2000

Yu JZ, et al. Identification of products containing -COOH, -OH, and -C=O in atmospheric oxidation of hydrocarbons. Environmental Science & Technology 1998;32(16):2357-2370.

   

5 cites in October-November 2001

Kleeman MJ, et al. Source contributions to the size and composition distribution of atmospheric particles: Southern California in September 1996. Environmental Science & Technology 1999;33(23):4331-4341.

   

4 cites in May 2002

Mallina RV, et al. High speed particle beam generation: a dynamic focusing mechanism for selecting ultrafine particles. Aerosol Science and Technology 2000;33(1-2):87-104.

   

4 cites in November-December 2001

Christoforou CS, et al. Trends in fine particle concentration and chemical composition in Southern California. Journal of the Air & Waste Management Association 2000;50(1):43-53.

Engineering

4

4 cites in June-July 2002

Sarnat JA, et al. Assessing the relationship between personal particulate and gaseous exposures of senior citizens living in Baltimore, MD. Journal of the Air & Waste Management Association 2000;50(7):1184-1198.

   

4 cites in February-March 2003

McMurry PH, et al. The relationship between mass and mobility for atmospheric particles: a new technique for measuring particle density. Aerosol Science and Technology 2002;36(2):227-238.

   

6 cites in April-May 2004

Zhu YF, et al. Concentration and size distribution of ultrafine particles near a major highway. Journal of the Air & Waste Management Association 2002;52(9):1032-1042.

   

4 cites in April-May 2004

Offenberg JH, et al. Persistent organic pollutants in the dusts that settled across lower Manhattan after September 11, 2001. Environmental Science & Technology 2003;37(3):502-508.

   

5 cites in May-June 2004

Park K, et al. Relationship between particle mass and mobility for diesel exhaust particles. Environmental Science & Technology 2003;37(3):577-583.

   

4 cites in November 2004

Canagaratna MR, et al. Chase studies of particulate emissions from in-use New York City vehicles. Aerosol Science and Technology 2004;38(6):555-573.

   

4 cites in November-December 2004

Drewnick F, et al. Measurement of ambient aerosol composition during the PMTACS-NY 2001 using an aerosol mass spectrometer, Part I: mass concentrations. Aerosol Science and Technology 2004;38(Suppl 1):92-103.

Author Self-Citation

Self-citations are journal article references to articles from that same author (i.e., the first author). Because higher author self-citation rates can inflate the number of citations, the author self-citation rate was calculated for the PM papers. Of the 9,578 total cites, 537 are author self-cites—a 5.6% author self-citation rate. Garfield and Sher2 found that authors working in research-based disciplines tend to cite themselves on the average of 20% of the time. MacRoberts and MacRoberts3 claim that approximately 10% to 30% of all the citations listed fall into the category of author self-citation. Therefore, the 5.6% self-cite rate for the PM papers is below the range for author self-citation.

1 Thomson’s Web of Science provides access to current and retrospective multidisciplinary information from approximately 8,700 of the most prestigious, high impact research journals in the world. Web of Science also provides cited reference searching.

2 Garfield E, Sher IH. New factors in the evaluation of scientific literature through citation indexing. American Documentation 1963;18(July):195-201.

3 MacRoberts MH, MacRoberts BR. Problems of citation analysis: a critical review. Journal of the American Society of Information Science 1989;40(5):342-349.

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