Knowledge structure and research trends of health impact assessment: A bibliometric review from 2000 to 2022

Abstract

Background:

Since the 1999 WHO Gothenburg consensus, health impact assessment (HIA) has evolved into a critical tool for evidence-based policy. However, a quantitative macro-level analysis of its global evolution over the last 2 decades remains scarce.

Objectives:

This study aims to quantify the global scientific production, identify key research hubs, map the intellectual structure, and detect emerging hotspots in HIA research from 2000 to 2022.

Methods:

A bibliometric analysis was conducted using the Web of Science Core Collection. Peer-reviewed English “Articles” published between 2000 and 2022 were included. To ensure bibliographic quality, records were manually screened to exclude irrelevant documents and early 2023 publications. Data analysis and visualization were performed using the R-package “bibliometrix” (version 4.1.2), VOSviewer, and ggplot2.

Results:

A total of 476 articles were included. The field exhibited a significant annual growth rate of 15.43%, with a notable surge after 2010. The United States (n = 80), the United Kingdom (n = 68), and Spain (n = 38) were the most productive countries. While traditional Western nations dominate, China is emerging as a significant research hub following the “Healthy China 2030” policy. Thematic analysis reveals a shift from foundational methodological concepts to specific environmental health determinants, particularly air pollution, particulate matter, and active transportation. The International Journal of Environmental Research and Public Health was the most prolific journal, while Environmental Health Perspectives held the highest citation impact.

Conclusions:

HIA research has matured into a robust, interdisciplinary field characterized by quantitative modeling of urban determinants. Despite rapid growth, a significant “North-South” implementation gap exists. Future research should prioritize HIA applications in the Global South and integrate gray literature to better capture practical policy impacts.

1. Introduction

Health impact assessment (HIA) is a systematic approach used to assess the potential effects of policies, programs, projects, or interventions on the health of individuals and populations.^[1] It aims to provide evidence-based recommendations and inform decision-making processes to promote positive health outcomes.^[2] The foundational tenet of HIA was initially elucidated after the World Health Organization (WHO) issued the Gothenburg consensus document on HIA in 1999, this seminal document, titled “Health Impact Assessment: Main concepts and suggested approach,” provided the definitive construct for the discipline.^[3] It outlined the primary purpose of HIA. Furthermore, the consensus document standardized the essential elements and stages of the assessment process. It also addressed critical questions regarding the relationship between HIA and other impact assessments, laying the groundwork for its integration into policy making.

Approximately 25 years have passed since the Gothenburg consensus imparted a definitive structure to the field. During this period, HIA has evolved from a novel concept into a globally recognized tool. However, existing literature reviews on HIA have predominantly been qualitative or limited to specific geographical regions and thematic niches. While these studies offer valuable insights into local practices and specific barriers, they often lack a macro-level, quantitative perspective on the global evolution of the discipline. As the field matures, there is a pressing need to retrospectively analyze the trajectory of HIA research to understand how scientific focus has shifted over the last quarter-century.

Bibliometrics encompasses a comprehensive analytical approach that predominantly focuses on quantitative analysis.^[4] Its intrinsic merit lies in the quantitative examination of various facets within a specific domain, such as the number of documents, citation patterns between documents, authorship, affiliations, and keywords.^[5] Leveraging the systematic and quantitative advantages offered by bibliometrics, this study employed a bibliometric methodology to analyze the field of health impact assessment. Through statistical and visual analyses of bibliometric data derived from published articles, this study aimed to address the following research questions:

Q1: What is the prevailing global trend concerning scientific publications related to HIA?

Q2: What valuable insights can be gleaned from this prevailing trend?

Q3: What are the forthcoming research directions and anticipated areas of focus in the realm of HIA?

2. Materials and methods

2.1. Literature search strategy

This study was conducted using the Web of Science Core Collection SCI Expanded database. The data collection was conducted on February 24, 2023. To ensure the retrieval of highly relevant literature, an advanced search strategy was employed using the “Author Keywords” field tag. The search query was formulated as: AK = (“Health Impact Assessment”). The time span for the search was set from 2000 to 2022 to capture the development of the field over the past 2 decades.

2.2. Data refinement and quality assessment

Following the initial search, data refinement was conducted based on document type and language. To ensure the quality and academic rigor of the analyzed literature, only peer-reviewed “Articles” were included; other document types such as reviews, meeting abstracts, and editorials were excluded. Additionally, the language was restricted to English to facilitate consistent text analysis. The records were manually screened to remove duplicate entries or irrelevant documents that did not align with the core topic of HIA. Ethical approval and informed consent were not required for this study as it involved the analysis of data derived from publicly available published literature.

2.3. Data abstraction

For each eligible document, the “Full Record and Cited References” were exported in plain text format. The variables extracted for analysis included: paper title, publication year, author names, author affiliations, funding agencies, document type, source journal title, abstract, author keywords, total times cited (TC), and cited references.

2.4. Data synthesis and analysis

Data analysis was performed using the R package “bibliometrix” (version 4.1.2) via its web-based interface, biblioshiny, tidyverse, ggplot2 and VOSviewer. The analysis was structured to correspond with the variables presented in the results:

1. Publication landscape: Descriptive statistics (frequencies and percentages) were used to analyze the annual scientific production. The annual growth rate was calculated to quantify the trend of publication volume over time.

2. Research countries and institutions: The geographic distribution of research was analyzed by mapping author affiliations. Collaboration networks between countries were visualized to identify key partnerships.

3. Most influential authors: Influence was operationally defined using 2 metrics: the H-index, which measures both productivity and citation impact, and Total Citations, reflecting the cumulative academic attention received by an author.

4. Most influential source journals: Bradford’s Law of Scattering was applied to identify the core journals (Zone 1) that publish the highest density of HIA-related articles. Journals were ranked by total publications and local citations.

5. Most influential papers: To identify seminal works within the specific domain of HIA, we used the Local Citation Score. Unlike global citations, Local Citation Score measures how many times a document has been cited by other documents within the selected collection, providing a more accurate measure of influence within the HIA research community.

6. Research Areas and Hotspots: Topic trends were analyzed using Author Keywords. Keyword co-occurrence networks and thematic evolution maps were generated to visualize historical shifts and current hotspots.

7. WOS Research Areas: Documents were classified based on the Web of Science (WoS) Subject Categories assigned by Clarivate Analytics. Since a single document can be classified into multiple research areas, a full counting approach was applied (i.e., a document assigned to 2 areas is counted once for each area).

3. Results

3.1. Search results and data screening

The initial search in the Web of Science Core Collection yielded a total of 590 records. To ensure the inclusion of high-quality original research, a rigorous screening process was applied. First, document types other than “Articles” were excluded; this removed 68 records, leaving 522 articles. Second, language restrictions were applied, excluding 40 non-English articles, resulting in 482 English articles. Finally, to strictly adhere to the study period (2000–2022), 6 articles published in early 2023 were excluded. A total of 476 articles met all eligibility criteria and were included in the final bibliometric analysis. The detailed screening process is illustrated in Figure 1, and the full list of included documents is provided in Table S1, Supplemental Digital Content, https://links.lww.com/MD/R440.

Figure 1.

Flowchart of the literature screening and selection process. This figure illustrates the systematic procedure used to identify relevant studies for the bibliometric analysis, following the PRISMA-style selection flow. Key findings: From an initial pool of 590 records, a total of 476 peer-reviewed articles were ultimately included after applying exclusion criteria for document type, language, and publication year. WoS = Web of Science, HIA = health impact assessment.

3.2. Descriptive bibliometric analysis

Table 1 summarizes the main bibliometric characteristics of the 476 included articles. The analysis covers the period from 2000 to 2022. As shown in the “Documents” section of the table, the field has experienced a significant Annual Growth Rate of 15.43%, with an average document age of 6.41 years. Figure 2 illustrates the annual publication trends. Since 2010, there has been a significant increase in the number of papers related to HIA, with the count reaching 47 in 2022, indicating that HIA is a developing field with a growing body of recent literature. Regarding “Authorship,” the dataset involves 2146 authors. The field is characterized by high collaboration, with an average of 5.76 coauthors per document and an international co-authorship rate of 36.55%. Notably, only 14 documents were single-authored, underscoring the collaborative nature of HIA research. In terms of “References and Citations,” the analyzed articles cited a total of 17,631 references. The average number of citations per document is 20.4, reflecting a healthy level of academic engagement and citation impact within the field.

Table 1.

Main bibliometric information of the HIA research (2000–2022) based on Web of Science data.

Category	Description	Value
Documents	Timespan	2000:2022
	Total documents	476
	Annual growth rate	15.43%
	Document average age	6.41
Authorship	Total authors	2146
	Single-authored documents	14
	Authors of single-authored documents	14
	Co-authors per document	5.76
	International co-authorships (%)	36.55%
Keywords	Keywords plus (ID)	1169
	Author’s keywords (DE)	1268
References and citations	Total references	17,631
	Average citations per document	20.4

Keywords Plus (ID): keywords associated with the manuscript’s cited references, generated by computer algorithms; Author’s Keywords (DE): keywords provided by the original authors.

Figure 2.

Annual scientific production and publication trends (2000–2022). This chart was generated using the R-package “bibliometrix” by calculating the frequency of HIA-related articles per year. Key findings: The field shows a steady upward trajectory with an annual growth rate of 15.43%. A significant surge in publications is observed after 2010, indicating the field’s transition into a more mature and globally recognized research domain. HIA = health impact assessment.

3.3. Research countries and institutions

A total of 50 countries contributed to the published literature on HIA. Table 2 shows the top ten countries based on their publication output and average citation frequency per paper. The United States (US) exhibited the highest publication output, with 80 papers accounting for 16.8% of the total and an average citation frequency of 29.7 per paper. The United Kingdom (UK) closely followed 68 papers (14.3%), with an average citation frequency of 23.6. Figure 3A compares the total number of articles against the average citations per article for the top countries. While US and UK lead in volume, the ranking for average citations differs, suggesting that high productivity does not always equate to the highest average impact per paper. Figure 3B illustrates the geographical concentration of the studies, with the majority concentrated in the northern part of the globe (particularly North America and Europe), while studies in the southern part are relatively scarce. A complete list of all 50 participating countries, organized by continent, is provided in Table S2, Supplemental Digital Content, https://links.lww.com/MD/R440.

Table 2.

Total articles, total citations and average number of citations in the top ten most highly cited countries.

Rank	Country	Continent	TA*	TC†	AAC‡
1	USA	North America	80 (16.81)	2379	29.7
2	United Kingdom	Europe	68 (14.29)	1608	23.6
3	Spain	Europe	27 (5.67)	1005	37.2
4	Italy	Europe	25 (5.25)	351	14.0
5	Australia	Oceania	24 (5.04)	566	23.6
6	China	Asia	23 (4.83)	458	19.9
7	Netherlands	Europe	23 (4.83)	247	10.7
8	Brazil	South America	22 (4.62)	157	7.1
9	Switzerland	Europe	20 (4.20)	361	18.0
10	France	Europe	15 (3.15)	255	17.0
10	Iran	Asia	15 (3.15)	462	30.8

^*TA, total articles.

^†TC, total citations.

^‡AAC, average article citations.

Figure 3.

(a) Comparison of total articles and average citations per article by country. (b) Geographical distribution of research production by country. This dual-axis chart (or bar chart) was generated based on the data in Table 2. Key findings: Although US and UK produce the highest volume of papers, countries with smaller total outputs often show higher average citation rates. This discrepancy suggests that citation impact is influenced by factors such as the “early adopter” advantage and the intensity of international collaborations. The visualization reveals a significant geographical imbalance: HIA research is heavily concentrated in the Global North, particularly in North America (US, Canada) and Europe (UK, Switzerland, Italy). In contrast, many regions in the Global South, including parts of Africa and Southeast Asia, show significantly lower publication density, indicating a need for more localized HIA studies in developing regions. HIA = health impact assessment.

Figure 4 illustrates global collaboration, highlighting the country’s links established in the field. The United Kingdom had the highest number of country links (44), followed by Switzerland (37), the United States (36), Germany (27), Italy (24), and the Netherlands (24).

Figure 4.

International collaboration network. This map was generated using VOSviewer.

A total of 353 institutions were involved in the HIA research. Table 3 presents the top ten cited institutions, which collectively accounted for 26 publications. The University of Cambridge received the highest number of citations, followed by the Centre for Research in Environmental Epidemiology, Tehran University of Medical Sciences, and the National Center for Epidemiology. Detailed information on all 353 institutions, including their country, is listed in Table S3, Supplemental Digital Content, https://links.lww.com/MD/R440. Analysis of the distribution of research output reveals that the top 115 institutions produced 50% of all documents, indicating a relatively dispersed research landscape. Among the top 10 research institutions, excluding the WHO European Centre for Environment and Health, there are 3 institutions in the United Kingdom, 2 in Spain, and one each in Switzerland, Germany, China, and Iran.

Table 3.

Top 10 institutions according to total number of citations.

Institution	Country	TC*	TA†
University of Cambridge	United Kingdom	275	2
Centre for Research in Environmental Epidemiology	Spain	246	2
Tehran University of Medical Sciences	Iran	226	3
National Center for Epidemiology	Spain	224	1
Nanjing University	China	175	2
University of Birmingham	United Kingdom	174	2
The London School of Hygiene & Tropical Medicine	United Kingdom	170	5
WHO European Centre for Environment and Health	-	158	1
Swiss Tropical and Public Health Institute	Switzerland	152	7
University of Stuttgart	Germany	152	1

^*TC, total citations.

^†TA, total articles.

3.4. WOS research areas

In this study, the number of research areas covered by HIA literature increased from one in 2000 to 22 in 2022 (Fig. 5). The top ten most productive research areas were Public & Environmental & Occupational Health, Environmental Sciences & Ecology, Meteorology & Atmospheric Sciences, Health Care Sciences & Services, Engineering, General & Internal Medicine, Infectious Diseases, Science & Technology - Other Topics, Toxicology, and Tropical Medicine, which represented 422 of the 476 publications and accounted for approximately 88.66% of the total. Figure 6 shows the annual evolution of the ten most productive areas of HIA research, illustrating the change in HIA research focus areas. Public & Environmental & Occupational Health, and Environmental Sciences & Ecology have long been the dominant research areas, with other areas being similar. A complete list of all identified research areas is provided in Table S4, Supplemental Digital Content, https://links.lww.com/MD/R440.

Figure 5.

Growth of Web of Science (WoS) research areas over time. This figure was generated by tracking the annual frequency of WoS subject categories assigned to the included articles. Key findings: The scope of HIA research has diversified significantly, expanding from a single research area in 2000 to 22 distinct areas by 2022. “Public, Environmental & Occupational Health” remains the primary dominant category throughout the study period. HIA = health impact assessment.

Figure 6.

Annual evolution of the top 10 most productive WoS research areas. This visualization was created using the “ggplot2” package in R to show the temporal shifts in research themes. Key findings: While environmental and public health areas remain stable, there is a visible increase in interdisciplinary research involving “Meteorology & Atmospheric Sciences” and “Infectious Diseases” in recent years.

3.5. Analysis of historical and current research hotspots

In this study, we detected 1267 author keywords from 476 papers published in HIA-related research between 2000 and 2022. Figure 7 shows the trends of author keywords over time, with the top ten keywords in the frequency ranking being health impact assessment, air pollution, particulate matter, mortality, physical activity, climate change, air quality, health policy, ozone, pm10. To analyze thematic shifts, the top 10 keywords across 4 time intervals are presented in Table 4. The evolution shows a clear transition from foundational concepts to specific determinants. During the earlier stages (2000–2010), research primarily centered on defining the HIA methodology and public policy applications, with early environmental concerns like air pollution and PM10 appearing alongside the emergence of environmental health impact assessment. In the subsequent period (2011–2015), the focus matured toward specific, measurable health determinants; particulate matter and public health became highly ranked, while key macro-environmental themes such as climate change entered the top ten alongside intervention areas like physical activity. In the most recent period (2016–2022), environmental factors (air pollution, particulate matter, air quality) remained dominant, but there was an increased focus on health outcomes like mortality and the emergence of immediate global health challenges, evidenced by the inclusion of Covid-19 in the top ten keywords.

Figure 7.

Thematic evolution and trends of author keywords. This trend map was generated using “bibliometrix” by analyzing the median year of appearance for the most frequent author keywords. Key findings: The research hotspots have shifted from foundational concepts (e.g., policy, methodology) toward specific environmental determinants (e.g., air quality, PM10) and contemporary global health challenges like COVID-19. HIA = health impact assessment, PM10 = particulate matter with a diameter ≤ 10 μm.

Table 4.

Evolution of the top 10 author keywords in HIA research (2000–2022).

Rank	2000–2005	2006–2010	2011–2015	2016–2022
1	Health impact assessment	Health impact assessment	Health impact assessment	Health impact assessment
2	Public policy	Air pollution	Air pollution	Air pollution
3	Air pollution; Pm10; environmental impact assessment; risk assessment; occupational health; health inequalities	Policy; modeling	Particulate matter	Particulate matter
4	Health policy; ozone; burden of disease; environmental health impact assessment; malaria; noise	Environmental health impact assessment	Public health; physical activity	Public health
5		Particulate matter; public health; mortality; climate change; Pm2.5; health policy; epidemiology; Pm10; life expectancy; malaria; built environment; healthy public policy; transport; walking; benmap; effectiveness; health services; human health; air quality modeling; anemia; attributable cases; biomass; decision making; European comparison	Climate change	Mortality
6			Health policy	Air quality
7			Environmental health; public policy; health needs assessment; health technology assessment; public health genomics	Physical activity
8			Mortality; ozone; health in all policies; quality of life; environmental health impact assessment; risk assessment; bicycling; malaria; modeling; population health; healthy public policy; evaluation	Pm2.5
9			Environmental impact assessment; epidemiology; Pm10; life expectancy; health equity; health promotion; nitrogen dioxide; effectiveness; noise; public health policy; traffic; air pollutants; Australia; European comparison	Covid-19
10			Pm2.5; Burden of disease; policy; social determinants of health; built environment; exposure; transportation; walking; air quality management; children; health effects; health services; human health; nutrition; air quality modeling; airq; anemia; biomass; cardiovascular diseases; cost-benefit analysis; decision making; diabetes; disability-adjusted life years; disease modeling; environmental assessment; external costs; fine particles	Climate change; ozone; epidemiology; burden of disease

3.6. Most influential source journals

A total of 171 journals published research related to HIA. A complete list of these journals is provided in Table S5, Supplemental Digital Content, https://links.lww.com/MD/R440. Table 5 presents the top ten journals with local citations in HIA-related research. According to Bradford’s Law of Scattering, 7 journals were identified as the fundamental source journals (Zone 1) in the field of HIA research. These core journals include titles such as such as “Atmospheric Environment” “Environment International” “Science of the Total Environment” “International Journal of Environmental Research and Public Health” and “Environmental Research.” Figure 8 provides an insight into the most prolific journals based on the number of published papers. A pronounced concentration of publications is observed among the top 5 journals, followed by a substantial drop-off in publication volume. Journals ranked 6 to 10 published markedly fewer papers, with publication counts ranging from 9 to 11, indicating that the top 5 journals constitute the dominant publication outlets in this field. The top 5 journals in terms of publication volume are the “International Journal of Environment Research and Public Health” with 59 papers, “Environment International” with 29 papers, “Public Health” with 23 papers, “Science of the Total Environment” with 19 papers, and “Environmental Research” with 14 papers.

Table 5.

Top ten journals according to total number of citations.

Sources	N.LC†	ND‡	IF 3	H Index
ENVIRONMENTAL HEALTH PERSPECTIVES	669	4	11.035	249
ATMOSPHERIC ENVIRONMENT*	494	10	5.755	211
LANCET	480	-	202.731	700
ENVIRONMENT INTERNATIONAL*	388	29	13.352	157
SCIENCE OF THE TOTAL ENVIRONMENT*	335	19	10.753	205
INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH*	291	59	4.614	78
ENVIRONMENTAL IMPACT ASSESSMENT REVIEW	277	-	6.122	-
JOURNAL OF EPIDEMIOLOGY AND COMMUNITY HEALTH	269	1	6.286	152
ENVIRONMENTAL RESEARCH*	261	14	8.431	113
ATMOSPHERIC CHEMISTRY AND PHYSICS	259	-	7.197	174

^*The journal is the core resource (classified by Bradford Law) of HIA research.

^†N.LC, number of the total local citation.

^‡IF, impact factor in 2022.

Figure 8.

Most prolific journals based on publication volume. This bar chart was generated in R to compare the output of the top-ranking journals. Key findings: The International Journal of Environmental Research and Public Health and Environment International are the leading outlets for HIA research. The top 5 journals were highlighted due to a pronounced drop-off in publication volume beyond this group. Journals ranked 6–10 published substantially fewer articles (ranging from 9 to 11), indicating that the top 5 journals dominate the literature and represent the primary publication outlets in this field. HIA = health impact assessment.

3.7. Most influential papers based on number of citations

Table 6 presents the top ten papers based on their local citation scores. To provide a deeper understanding of these seminal works, a detailed summary of their characteristics is presented in Table 7, including study aim, design, and outcomes. Among these, the most influential paper is titled “Replacing car trips by increasing bike and public transport in the greater Barcelona metropolitan area: a health impact assessment study.”^[6] This study examined the health impacts of replacing car trips with cycling and public transport in the Barcelona metropolitan area. This study found that such mode shifts would result in significant health benefits, including reduced mortality rates and increased life expectancy, primarily through decreased exposure to air pollution and increased physical activity. Additionally, the transition would lead to a substantial reduction in carbon dioxide emissions, contributing to environmental sustainability. Papers 4 and 8 also examined measures to promote bicycle and public transport use in cities and assessed and analyzed the health impact of these measures, exploring the health benefits of reducing car travel and increasing cycling and public transport use, as well as the associated disease incidence and burden.^[7,8]

Table 6.

Top ten papers according to the local citation score.

Document	DOI*	Year	LCS†	GCS‡
ROJAS-RUEDA D, 2012, ENVIRON INT	10.1016/j.envint.2012.08.009	2012	18	153
HEROUX ME, 2015, INT J PUBLIC HEALTH	10.1007/s00038- 015-0690-y	2015	13	158
BOLDO E, 2006, EUR J EPIDEMIOL	10.1007/s10654-006-9014-0	2006	12	224
ROJAS-RUEDA D, 2013, PREV MED	10.1016/j.ypmed.2013.07.021	2013	12	93
HUBBELL BJ, 2009, AIR QUAL ATMOS HLTH	10.1007/s11869-009-0037-z	2009	11	62
XIA T, 2015, ENVIRON INT	10.1016/j.envint.2014.10.004	2015	11	118
WINKLER MS, 2020, INT J ENV RES PUB HE	10.3390/ijerph17092988	2020	11	34
MUELLER N, 2017, ENVIRON INT	10.1016/j.envint.2017.07.020	2017	10	54
NADDAFI K, 2012, IRAN J ENVIRON HEALT	10.1186/1735-2746-9-28	2012	9	174
HAIGH F, 2015, BMC PUBLIC HEALTH	10.1186/s12889-015-2319-8	2015	9	32

^*DOI, Digital Object Identifier.

^†LCS, Local Citation Score.

^‡GCS, Global Citation Score.

Table 7.

Summary of the top 10 most influential papers in HIA research.

First author (yr)	Country	Study aim	Study design	Health outcome(s)	Environmental outcome(s)
Rojas-Rueda (2012)	Spain — Greater Barcelona metropolitan area	Estimate health risks/benefits of shifting car trips to cycling and public transport	Health impact assessment (8 transport scenarios, modeling travelers + general population)	All-cause mortality, cause contributions (physical activity benefits, air-pollution deaths, road-traffic fatalities); change in life expectancy	Change in PM2.5 exposure; CO2 emissions reduction
Héroux (HRAPIE) (2015)	Europe/ WHO-Europe (multi-country guidance)	Provide evidence-based concentration–response functions and guidance to quantify health impacts of ambient air pollutants	Expert review and synthesis; recommendation of C-R functions for policy use	Mortality and morbidity linked to PM, O3, NO2 (short- and long-term effects)	Air pollutant metrics (PM, O3, NO2) and recommended exposure–response specification
Boldo (Apheis) (2006)	Multi-city Europe (23 cities)	Quantify public-health impact of long-term PM2.5 exposure across European cities	HIA using WHO methodology, PSAS-9/ AirQ software	Attributable premature deaths (all-cause, cardiopulmonary, lung cancer); gain in life expectancy	Long-term PM2.5 concentrations (current vs target 15 µg/m3)
Rojas-Rueda (2013)	Spain — Barcelona metropolitan area	Quantify morbidity and burden of disease from reduced car trips/ increased active & public transport	HIA (morbidity outcomes) across 8 transport scenarios; burden-of-disease estimation	Reduced incident cases: diabetes, cardiovascular disease, dementia, cancers, injuries; DALYs prevented	Reduced PM2.5 exposure for travelers and general population
Hubbell (Levy et al.) (2009)	United States (methodological focus)	Examine data/analytical challenges for credible local-scale HIAs (ozone, PM2.5) and give recommendations	Analytical review and guidance	Guidance for estimating incidence of pollution-related health effects (mortality/morbidity) at local scale	Issues and recommendations for using local ozone and PM2.5 data (spatial/temporal resolution)
Xia (2015)	Australia — Adelaide, South Australia	Quantify health co-benefits of shifting trips to alternative transport (air quality + physical activity)	Scenario modeling: air-quality models + comparative risk assessment	Deaths and DALYs prevented from improved air quality and increased physical activity; changes in traffic injuries	Reduction in urban PM2.5; reduced vehicle-kilometers traveled (VKT)/ emissions
Winkler (et al.) (2020)	International (survey across 29 countries)	Describe current global HIA practice, trends, barriers and promoters	Cross-sectional online practitioner survey (n = 122) + descriptive analysis	Not an exposure-outcome HIA — reports application areas and perceived impacts of HIA practice	Not applicable (study of HIA practice across countries; documents contexts where environmental exposures are assessed)
Mueller (UTOPHIA) (2017)	Spain — Barcelona (city-level)	Estimate city-level burden of disease due to exposures influenced by urban & transport planning	Burden-of-disease assessment using the UTOPHIA tool (PA, air pollution, noise, heat, green space)	DALYs and attributable morbidity/mortality for physical activity, respiratory/cardiovascular outcomes, noise-related sleep disturbance, etc	Exposures: physical activity levels, PM, traffic noise, urban heat, green-space access
Naddafi (Tehran) (2012)	Iran — Tehran megacity	Provide quantitative estimates of health impacts of air pollution in Tehran	HIA using WHO AirQ software with measured pollutant concentrations	Attributable excess mortality (total, cardiovascular, respiratory)	Ambient concentrations: PM10, SO2, NO2, O3
Haigh (et al.) (2015)	Australia & New Zealand (multi-setting)	Identify factors associated with HIA effectiveness in influencing decisions and implementation	Mixed methods: document review of 55 HIA reports, surveys/interviews (48), 11 case studies; thematic analysis	Process/outcome measures of HIA effectiveness (influence on decisions, implementation) — health outcomes vary by HIA	Not an exposure study — applies across sectors (environmental outcomes depend on individual HIAs)

Papers 2, 3, 6, and 9 deal with the health effects of ambient air pollution.^[9–12] They explored different regions (Europe, South Australia, and Iran) to assess the health effects of long-term PM10 exposure and traffic-related air pollution.

Papers 5, 7, and 10 deal with the practical experience of HIA in different countries and regions and introduce possible resistance in practice and actions to promote the development of HIA.^[13–15]

3.8. Most influential authors based on H-index in 2022

The dataset involves 2146 authors. For the entire author population, the H-index ranged from 0 to 16, and the total number of citations ranged from 0 to 867. Table 8 lists the top ten most influential researchers. These top ten authors represent approximately 0.47% of the total author population, highlighting a concentrated core of high-impact researchers. David Rojas-Rueda has the highest H-index and the highest number of citations in the Web of Science Core Collection, with 16 articles published as of 2022. Geographically, among the top ten most influential researchers, there are 5 researchers from Switzerland, 2 from Spain and US respectively, and one from Australia and France.

Table 8.

Top 10 most influential authors ranked by the H index.

Element	H index	g index	m index	TC*	NP†	PY start ‡	Country
David Rojas-Rueda	10	16	0.833	867	16	2012	Spain
Jürg Utzinger	9	11	0.563	158	11	2008	Switzerland
Mirko S Winkler	9	13	0.75	177	14	2012	Switzerland
Mark J Nieuwenhuijsen	8	9	0.667	666	9	2012	Spain
Mark J Divall	7	7	0.583	111	7	2012	Switzerland
Neal Fann	7	7	0.467	468	7	2009	USA
Astrid M Knoblauch	7	7	0.7	121	7	2014	Switzerland
Nino Künzli	7	9	0.318	395	9	2002	Switzerland
Fiona Anne Haigh	6	7	0.545	146	7	2013	Australia
Sheena E Martenies	6	6	0.667	101	6	2015	USA
Sylvia Medina	6	7	0.333	370	7	2006	France

^*TC, Web of Science Core Collection times cited count.

^†NP, number of scientific productions.

^‡PY start, First year published.

4. Discussion

This study aimed to analyze the global trends, knowledge structure, and future directions of HIA research from 2000 to 2022 using bibliometric methods. The analysis of 476 articles yielded 4 key findings: HIA research has transitioned from a nascent concept to a rapidly growing field, particularly after 2010; there is a significant geographical imbalance, with the Global North (US, UK, Spain) dominating research output, along with a notable discrepancy between publication volume and citation impact across countries; the thematic focus has shifted from methodological frameworks to specific environmental determinants like air pollution and transportation; and a core group of influential authors and journals are shaping the academic discourse, with a distinction between high-volume productivity and high-citation impact.

The first key result is the significant annual growth rate of 15.43% in HIA publications, with a marked surge post-2010. This aligns with the global diffusion of the “Health in All Policies” (HiAP) framework.^[16] The initial lag following the 1999 WHO Gothenburg consensus suggests a gestation period where HIA was being integrated into national frameworks. The rapid increase after 2010 likely corresponds with major policy milestones, such as the inclusion of HIA in the United States’ “National Prevention Strategy” in 2011.^[17] Unlike early qualitative reviews, this quantitative trend confirms that HIA has matured from a theoretical proposition into a widely applied research tool. This upward trajectory indicates that HIA is increasingly recognized as essential for evidence-based decision-making in non-health sectors.

The second key finding highlights the dominance of the United States, the United Kingdom, and Spain in HIA research. The top 3 countries in terms of the number of publications related to HIA are the United States, the United Kingdom, and Spain. The findings of this study align with previous research, indicating that the practice of HIA is predominantly active in Europe and North America.^[14] The United Kingdom has a wealth of experience in HIA theory and practice.^[18] In 1999, the UK government introduced the consideration of HIA in policy, planning, and project development at both national and local levels in its public health strategy documents.^[19] Through funding various related studies, the UK has established a relatively comprehensive HIA training mechanism.^[20] In 2011, the United States National Prevention Council included HIA in the “National Prevention Strategy” highlighting its utility in helping decision-makers assess projects or policy choices to enhance positive health outcomes while minimizing adverse health outcomes and health disparities.^[21] Concurrently, the publication of the National Research Council’s framework in 2011 provided the first comprehensive and rigorous guidance for conducting HIAs, effectively standardizing the methodology across federal and state levels.^[17] The utilization of HIA has significantly increased since its initial implementation in the United States.^[22] While the leadership of the US and UK is expected given their early adoption of HIA legislation, Spain’s third-place ranking is a novel finding. This is likely attributable to the prolific authors focusing on urban health models. Conversely, the bottom ten countries contribute minimally to the literature. This disparity points to a significant implementation gap in the Global South, where a lack of legal mandates, funding, and technical capacity hinders HIA research. As shown in our results, HIA articles related to China have gradually become a new research focus. This empirical growth is directly linked to major domestic policy shifts, most notably the “Healthy China 2030” plan.^[23] This national strategy emphasizes the integration of health into all policies and calls for the comprehensive establishment of a health impact assessment system. This system aims to systematically assess the impact of various economic and social development plans, policies, and major engineering projects on health while also enhancing monitoring mechanisms.^[24] The surge in publication volume visibility from China identified in our study provides quantitative evidence of how high-level policy mandates translate into academic output.

However, a discrepancy was observed between the number of publications and the average citations per article across different countries (Fig. 3a). While US and UK lead in total output, countries with fewer publications sometimes exhibit higher average citation rates. This may be attributed to the “early adopter” advantage, where seminal papers from pioneering countries accumulate citations over a longer period. Additionally, high international collaboration rates often correlate with higher citation impacts due to broader visibility. Conversely, countries with rapidly growing but more recent publication outputs may not yet have accumulated comparable citation averages. This discrepancy suggests that high productivity does not always equate to the highest scientific impact within the HIA community.

The third key finding indicates that the thematic focus has shifted from broad concepts (“Health Policy,” “Methodology”) to specific, measurable determinants (“Air Pollution,” “Particulate Matter,” “Transport”). This shift reflects the integration of HIA into urban planning and environmental policies. The prominence of environmental health topics aligns with current global priorities regarding climate change and sustainable cities. This link clarifies that HIA is primarily being operationalized to assess the health co-benefits of climate mitigation strategies (e.g., active transport). Unlike earlier periods focused on defining what HIA is, current research focuses on quantifying impacts. This transition from qualitative process evaluation to quantitative modeling represents a significant maturation in the scientific depth of the field.

Finally, the fourth key finding reveals that a core group of journals and authors are shaping the academic discourse, further reflecting the gap between publication volume and citation impact. While the International Journal of Environmental Research and Public Health publishes the most articles and is a fully open-access journal, Environmental Health Perspectives which is also an open-access journal, garners the highest local citations, indicating that researchers must balance open-access visibility with disciplinary prestige. Furthermore, the influential papers identified in this study heavily overlap with the top authors (e.g., David Rojas-Rueda), confirming that the field is driven by a concentrated core of experts. David Rojas-Rueda, Mirko S. Winkler, and Jürg Utzinger are the top 3 authors in terms of the number of publications and H-index ranking in the field of HIA. They have conducted HIA-related research from different perspectives. David Rojas-Rueda primarily focuses on HIA related to transportation modes, such as walking and cycling, as well as urban planning.^[25–27] Mirko S. Winkler’s and Jürg Utzinger’s research is more centered on HIA in the context of natural resource extraction projects and comprehensive research on HIA as a field.^[28–31] These seminal papers largely focus on quantitative models of transport and air pollution in European cities. This finding implies that the “intellectual center” of HIA research is currently defined by quantitative modeling of urban determinants, rather than broad social policy assessments.

This study has several strengths, including the use of the Web of Science Core Collection, which ensures high-quality data, and the application of rigorous bibliometric tools to provide a 22-year longitudinal view. Furthermore, a key strength of this study is the high availability and accessibility of HIA-related information within the existing literature. The existence of a substantial and well-documented body of research provided a rich dataset, enabling a robust and comprehensive analysis of global trends and ensuring that the identified knowledge structures are representative of the field’s actual evolution. However, limitations exist. First, the restriction to English-language peer-reviewed articles excludes “gray literature” (government reports, unpublished HIAs), which constitutes a significant portion of practical HIA work. Consequently, this study may underestimate the practical application of HIA in nonacademic settings. Second, the analysis is limited to the metadata available in WoS, and citation metrics may not fully capture the policy impact of HIA reports that are not cited in academic journals.

5. Conclusions

This bibliometric analysis demonstrates that HIA has evolved into a robust, rapidly expanding field of research, driven largely by environmental health concerns and urban planning policies. The trajectory of the field shows a clear movement from defining methodological processes to quantifying specific health impacts, particularly regarding air pollution and transportation. However, the field is characterized by significant geographic inequality. Research is heavily concentrated in North America and Western Europe (notably US, UK, and Spain), leaving a critical knowledge gap in low- and middle-income countries where rapid urbanization and environmental degradation make HIA most urgent. The academic discourse is shaped by a core group of researchers and journals, with a strong emphasis on quantitative modeling.

Based on these findings, future research should focus on 3 areas: There is an urgent need to conduct and publish HIA studies in the Global South to understand context-specific barriers and health determinants in developing regions. Future bibliometric reviews should attempt to integrate gray literature databases to capture the practical, nonacademic implementation of HIA. While transport and air pollution are well-studied, researchers should apply HIA frameworks to emerging challenges beyond urban design.

Author contributions

Conceptualization: Zhen Wang, Xiaohua Qi.

Data curation: Shujuan Yin, Juan Hou.

Methodology: Yuhang Xing.

Project administration: Zhen Wang.

Supervision: Zhen Wang, Xiaohua Qi.

Visualization: Yuhang Xing.

Writing – original draft: Yuhang Xing.

Writing – review & editing: Shujuan Yin, Juan Hou.

Supplementary Material

medi-105-e47792-s001.xlsx ^{(77.8KB, xlsx)}