3.1 References network
Table 2 shows the top ten reference citations, including the number of citations, author details, paper published in journal, and DOI for easy access to the paper, and for the top 10 cited references a mapping network is given in Figure 1. Among the top ten citation count references is a paper entitled nature and health which was published in the Annual Review of Public Health journal published by Terry & Hartig (2014), with a citation count of 170, the highest found in the data. The author investigated that due to increasing urbanization, resource degradation and social life changes had a significant effect on nature as well as human health. Furthermore, this study takes nature as the physical environment owing to the consideration of increasing urbanization and population demand for natural resources in order to keep a sustainable green environment to aid public health. The 2nd position was taken by Wolch et al (2014), with a citation count of 92. Wolch investigated environmental justice, public health, and urban green space and aimed to make cities green enough. This study followed the literature of Anglo-American green urban space, especially considering public parks, and compared the USA with large Chinese cities. In the USA, many cities have adopted a policy to increase the supply of green urban environments to make neighborhoods healthy, as well as implementing policies to reform land into green urban environments. Similar policies were followed by China in many big cities, while the Chinese land is state owned; regardless, the Chinese government took the initiative to make urban areas green and reduce environmental pollution to aid sustainable public health. The third is Mireia et al (Mireia, Margarita et al. 2015), with a citation count of 88. This study conducted a systematic review of 28 studies and investigated green and blue environments and their long-term mental health exploitation. The conclusion of this study reveals that there is limited evidence that green spaces positively and significantly improve the mental health of adults, but in the case of children the literature has many studies whose results found highly positive and significant improvements in their mental health due to green environments. Further, this study suggests that green urban environmental planning is compulsory to produce clever children for the future.
With a citation count of 79, Lee & Maheswaran (Lee and Maheswaran 2011) ranked fourth among the top ten citation counts. Lee & Maheswaran performed a literature review on the health benefits of green urban environments, and their conclusion is that there is not enough strong correlation between urban space, mental health, and wellbeing. They also found that natural environmental resources such as green environments positively influence physical activity. Although many studies have concluded that green environments have a positive influence on public health, this remains hard to overcome with strong correlation. The fifth study, with 58 citation counts, was conducted by Markeyach et al (Markevych, Schoierer et al. 2017); this study explored the green environment pathway linkages, and concluded that although there is enough evidence that the green environment effect is correlated with public health, the pathway of green environment remains, including functions such as how green environments affect public health, age groups, and what health outcomes result from a green environment. This study gives a clear missing link of research needing to be done.
The sixth study was by Triguero-Mas et al (Triguero-Mas, Dadvand et al. 2015), with a citation count of 58. This study analyzed the nexus mechanism between outdoor green environment, and physical and mental health. The conclusion of this study reveals that the outdoor green environment is significantly correlated with gender specification, socioeconomic conditions, and mental health. The seventh study counts 57 citations and is by De Veries et al (De Vries, Van Dillen et al. 2013). De Veries analyzed the three mechanisms of stress reduction, improving mental health, and facilitating the social cohesion to improve physical involvement by collecting the data of 1641 respondents with an emailed questionnaire. The results of this study reveal that there is a strong mediation between stress and social cohesion with outdoor green environments, but full physical condition does not show mediation with outdoor green environments. Furthermore, in this study respondents often participated in outdoor green environmental activities; this was not found to be significant. Beyer et al (2014) ranked eighth among the top 10 citation counts. Bayer et al explored the mental health environmental green space by using the survey data from the USA. The results of this study reveal that environmental green spaces are highly significantly correlated with depression, stress, and anxiety. Additionally, this study suggested improving green environments in the USA would improve the mental health of the population. The ninth study, by Gascon et al (Gascon, Triguero-Mas et al. 2016), recorded a citation count of 54. Gascon et al completed a literature review based study in order to explore and understand the correlation between green environments and mortality. The conclusion of this study reveals that people who are living in lush green environments are much less influenced by cardiovascular disease; their mortality rate is also lower compared to people who live in non-green environments. This further suggests that studies related to green and blue environments with socioeconomic conditions need to be further investigated. Alcock et al (Alcock, White et al. 2013), ranked tenth, with 52 citations recorded; by using British panel survey data with 5320 observations, this study investigated the effect on mental health by moving in less green environments and lush green urban areas. The results found that moving in green urban areas is highly positive and significantly correlated with improving mental health, as well as reducing stress.
Table 2
Citation counts of the top 10 references
Citation
|
Author
|
Journal
|
DOI
|
170
|
Terry & Hartig (2014)
|
Annual Review of Public Health
|
https://doi.org/10.1146/annurev-publhealth-032013-182443
|
92
|
Wolch, Byrne & Newell (2014)
|
Landscape and Urban Planning
|
https://doi.org/10.1016/j.landurbplan.2014.01.017
|
88
|
Mireia et al., (2015)
|
International journal of environmental research and public health
|
https://doi.org/10.3390/ijerph120404354
|
79
|
Lee & Maheswaran (2011)
|
Journal of Public health
|
https://doi.org/10.1093/pubmed/fdq068
|
58
|
Merkevy et al (2017)
|
Environmental research
|
https://doi.org/10.1016/j.envres.2017.06.028
|
58
|
Triguero-Mas et al (2015)
|
Environment International
|
https://doi.org/10.1016/j.envint.2015.01.012
|
57
|
De Veries et al (2013)
|
Social Science and Medicine
|
https://doi.org/10.1016/j.socscimed.2013.06.030
|
56
|
Beyer et al (2014)
|
International journal of environmental research and public health
|
https://doi.org/10.3390/ijerph110303453
|
54
|
Gascon et al (2016)
|
Environment International
|
https://doi.org/10.1016/j.envint.2015.10.013
|
52
|
Alock et al (2013)
|
Environmental science and technology
|
https://doi.org/10.1021/es403688w
|
Furthermore, from the co-citation mapping the top 20 burst references were detected with strong burstness, as well as a sudden increase in citation counts; this indicates the peer review interest in the research field of green environments and public health. Figure 2 shows the results of the top 20 strong bursts references.
3.2. Journals research mapping network
The journal visualization mapping network is another feature to visualize the green environments and public health field. For this analysis, the based on the node the setting of CiteSpace was fixed to cite journals, for the journal visualization network mapping the 5916 documents record were analyzed. The merged network nodes resulted by CiteSpace were 1078 and the links density form one node to another node found 9767, then top 10 highly cited journal were visualized.
Table3: Visualization of the top 10 journals
Frequency
|
Full title
|
Abbreviation
|
Publisher
|
IF-2019-2018
|
Bursts
|
Certainty
|
2072
|
Environmental science and Technology
|
Environ Sci Technology
|
ACS Publications
|
6.198
|
62.26
|
0.99
|
1783
|
Science of the total environment
|
Sci total environ
|
Elsevier
|
6.55
|
47.19
|
0.81
|
1717
|
Chemosphere
|
Chemosphere
|
Elsevier
|
5.78
|
36.66
|
0.77
|
1517
|
Environmental Pollution
|
Environ Pollu
|
Elsevier
|
6.79
|
36.34
|
0.76
|
1320
|
Water Research
|
Water Res
|
Elsevier
|
9.13
|
34.94
|
0.76
|
1157
|
Journal of Hazardous Materials
|
J Hazard Mater
|
Elsevier
|
9.03
|
34.40
|
0.75
|
1132
|
Science
|
Science
|
American Association Advancement Science
|
41.84
|
33.19
|
0.74
|
984
|
Environment International
|
Environ Inter
|
Elsevier
|
7.57
|
31.77
|
0.73
|
894
|
Plos one
|
Plos one
|
Public Library Science
|
2.74
|
27.32
|
0.73
|
879
|
Environmental toxicology and Chemistry
|
Environ Toxico Chem
|
Wiley
|
3.15
|
25.87
|
0.71
|
The results of Table 3 and Figure 3 represent the visualization network of highly cited journals and their frequency. The highly cited journals are sorted with large nodes and according to place the auto node size was fixed. Among the top 10 journals, the top ranked journal was Environmental Science and Technology (ES&T), with citation counts of 2072 for the publication of green environments and public health. ES&T is a multidisciplinary journal who published the paper environmental related audience work, as well as providing authors, researchers, and policy makers with information upon which to make their decisions. ES&T has been a foundational focus for thought-leading, policy-changing contributions and will continue to serve as the home for significant, broadly relevant, and generalizable research that serves to inform decision-making.
The second ranked journal is the Science of the Total Environment (STOTEN), with a citation count of 1738. STOTEN is also an international multidisciplinary journal publishing research related to hypothesis driven, novel work and has a high impact on the environment, particularly in regards to the lithosphere, astrosphere, hydrosphere, biosphere, and atmosphere fields. With a citation count of 1717, the Chemosphere journal ranked third among the top 10 journals. Chemosphere was originally designed for communication related papers and literature reviews. It also publishes high impact research related to the environment and engineering. The fourth journal is Environmental Pollution, with a citation count of 1517. Environmental Pollution publishes high quality research and review papers in the discipline of environmental pollution and employs a peer review publication process. The fifth journal recognized is Water Research, with a citation count of 1320. Water Research publishes papers related to science and technology, including anthropogenic, water quality, and water recycling research. The Journal of Hazardous Material (JHAZMAT), with a citation count of 1157, ranked sixth. JHAZMAT publishes papers related to public health impacted by environmental effects, environmental science, environmental engineering, risk mitigation, and hazardous material. The seventh journal is Science, a multidisciplinary and highly significant research publication journal related to the environment and other disciplines. The Environmental International journal covers health impact assessments, environmental epidemiology, and environmental health risk assessments. The Environmental International journal is ranked eighth, with a citation count of 987. The ninth journal is PLOS One, with a citation count of 894. PLOS One is also a multidisciplinary journal which publishes high impact research related to medicine, social sciences, all science related research, and engineering. Environmental Toxicology and Chemistry is ranked tenth and publishes papers related to theoretical work, original experiments, and significantly advanced research related to environmental toxicology.
3.3. Country and institutes visualization mapping network
Country visualization is also an important feature to aid in understanding which countries are actively carrying out research related to green environments and public health. The Citespace selection of node type was fixed to country and the top 10 countries were selected from the merged nodes 568, as shown in Figure 4.
In the case of country mapping visualization, the USA, Republic of China, England, India, Spain, Australia, Germany, Canada, and Italy were selected as the top countries doing research on green environments and public health. China ranks first, followed by the USA. The USA has a history of being a developed country, therefore in earlier years focused on green environments and public health. China is still running towards the pathway of development, but is rapidly developing. This speed of development, however, brings about environmental pollution in China. Therefore, latterly China also considers green environments and public health for the sustainable development of the nation. By the literature’s visualization, England and India are also quite concerned with green environments and public health, England is also a developed country but India belongs to the list of developing countries. Due to high population pressure and industry, India is also actively researching green environments and public health. Australia, Canada, Germany, and Spain are also developed countries with less population; therefore, their contribution in green environment research has been less compared to the USA, China, and India.
The visualization networking map presented in Figure 5 is for the most influential institutes focusing on green environmental and public health. The most active institute is from China, the Chinese Academy of Sciences (CAS). This is the national academy for natural sciences and natural resources, and the headquarters of CAS is located in Beijing, the capital city of China. Since 2016, the CAS ranked as the number one academy around the world in the nature index. It is also the world’s largest academy, where more than 60,000 researchers are working in different research directions. The University of Exeter, located in Devon, United Kingdom, is also an active institute and ranked second. The University of Exeter are doing influential research related to green environments and public health; it was established in 1955 and with time developed over four campuses. It is also a member of the European University Association, Universities UK, and the Association of Commonwealth Universities. The third institute is the Chinese Academy of Sciences (UCAS), a public university for undergraduate and graduate students working under the leadership of CAS. UCAS was established in 1978. It was the first graduate school to approve state council technology of China. UCAS ranked first in China and eighteenth in the performance ranking regarding publishing scientific research around the world. The fourth ranked institute is the City University of Hong Kong, which was founded in 1984 as the City Polytechnic of Hong Kong; the current name was revised in 1994. The University of Melbourne was established in 1853 and ranked fifth among those universities who are active in doing research related to green environments and public health. More information on active institutes is given in Figure 5. In the literature, published papers are collaborated with the international institutions which are most influential in the research field of green environments and public health (Valera-Gran, Prieto-Botella et al. 2020).
3.4. Author’s visualization mapping network
Considering the map of authors co-citation, this study analyzes the top 10 highest citation count and the most active on doing research related to green environments and public health. A merged network was created with 724 nodes, which are the corresponding cited authors, with 1140 links recorded. The most frequently cited author with the largest node is Mark J Nieuwenhuijshen, followed by Giovanni Benelli, Payam Dadvand, Xavier Basagana, Chellasmay Panneerselvam, and Jayapal Subramaniam in their respective positions. The highest bursts were Giovanni Benelli, Devalumar Dinesh, Udayan Suresh, and Kadarkarai Muragan and highest burst were steamed with the certainty, which indicates the structure of the relevance in the networking of visualization. The top authors with the highest certainty were Payam Dadvand, Mark J Nieuwenhuijsen, Xavier Basagana, and Marta Cirach.
3.5. Visualization of keywords and categories
The research focus was investigated by examining the keywords to find the pathway of research in a certain period of time, which indicates the discipline of large scale publications, the attentiveness of research concepts, and appearance of a great number of researchers who are doing research in parallel (Leung, Sun et al. 2017). From previous literature, one scholar argues that scientific development is an alteration of traditional science and modern science (Kuhn and Hacking 2012). This means that scientific research is changing over time and income insurability among old and contemporary approaches, because vocabulary changes accordingly. Therefore, we can observe that the existence of a revolution occurred by the changes in vocabulary. The statistics of the figure of keywords that occurred in the previous literature imitates the significance of keywords in this period to a specific research area (Wang, Guo et al. 2019). Thus, keyword co-citations can show a missing link of research in a certain specific research area. The co-word approach first proposed by Callon et al. (1983) is widely used in the research field of information science. The concept of co-citation ideas in bibliometrics is driven by the co-word examination. Therefore, it is scientifically proven that in two scientific terms an “inscription of keywords” exists in a published research work in the same time, indicating that there is a significant nexus between these two papers with similar keywords, if the words appear more times, each time brings them closer together (Zhang and Xu 2008). The bibliometric analysis is the sum of all co-citations, co-words, and co-term analysis.
For the co-word or keywords, an occurrence analysis was retrieved from the merged nodes of 709 associated links, with 6479 for green environments and public health. In Figure 7 are the top co-occurring keywords. From Figure 5, we can see that there are different groups which connect to each other and describe how environment affects health. Group one describes the environmental pollution, drinking water, contamination of heavy metal, toxicity, and group two describes the effect on physical health, mental condition, mortality, etc. Although the keywords are different from each other, the main objective of each study presented defined how green environments affects public health, physiology, and mental stress.
The most influential node is presented with the thickness, and the colour changes over time.
For a clear understanding, there is a cloud of each keyword occurrence, as well as identification of a missing research pathway. This study analyzes the frequency of keywords by category because it is more efficient to understand and find the missing pathfinder research for green environments and public health. Figure 8 is summarized in four groups: (1) environmental science and ecology, (2) public, environmental and occupational health, (3) marine and freshwater biology, and (4) biotechnology and applied microbiology. These four groups appeared twice with high thickness and colour stratified nodes.
Environmental science and ecology
Here, environmental sciences reflect all environmental aspects of research which directly and indirectly connect to the health keywords such as water contamination, environmental pollution, carbon emission, and air quality. When environmental pollution increases, it directly affects human physical activities and mental health (Barbara 2014). From Figures 7 and 8, it is clear that not only is there a large proportion of keywords going to the environment but also going from various categories with a high frequency cloud. It is also worth noting that big data and visualization analysis identifies the correlation between green environments and public health. It is confirmed that ecosystem and environment pathways of research trends are connected such as in ecosystem cultural activities, which can also provide significant aesthetic environmental and recreational opportunities to improve physical activities. These, in turn, are directly connected with physiological and sociological health conditions (Zhang, Yu et al. 2020). In the literature, there is enough strong evidence that physical environmental activities could reduce the risk of cardiovascular disease (Thompson, Roe et al. 2012, Van den Berg, Wendel-Vos et al. 2015)
Considering the dearth of literature, it has already considered physical and mental health in relation to urban green spaces and concluded that the physical social contact with green environments can overcome many physical benefits (Rios, Aiken et al. 2012, Fone, White et al. 2014). But according to co-occurrence keywords, there is still a missing pathway of research concerning physical and social activities. The findings of this research are to support a study published by Hertig et al (2014) concluding that the environmental social coherence pays little attention. As compared to physical health, social health received relatively lower attention concluded by Keniger et al (Keniger, Gaston et al. 2013). The correlation of health and social cohesion with green environment might declare a highly significant mediation because it is directly connected with human loneliness, feelings, and stress (Maas, Van Dillen et al. 2009). However, the correlation of social cohesion and green environment is not widely investigated, therefore researchers need to fill this research gap.
Public, environmental, and occupational health
Public, environment, and occupational health is a very important discipline in medical and biological research. Research related to public, environment, and occupational health put a shed on the current health situation, including coronary disease caused by changes in environment and health related policies, as well as the standard of public health. Sweileh et al (2014) performed a bibliometric analysis on research activities in Arab countries regarding public, environmental, and public health and concluded that public health research is not only rising in European countries but in Arab countries it is the popular for doing research related to environmental effect on public health as well as occupational health found relatively lower. Figures 7 and 8 show the dominancy of the keywords declaring the theme of public, environmental, and public health, with very high frequency thick nodes and colours over time. The available literature was mainly focused on how and to what extent green environment is associated with public health, mental health, and wellbeing (McMahan and Estes 2015, Gascon, Triguero-Mas et al. 2016). While the main objective was to connect the relationship between public health, occupational health, and green environment (Markevych, Schoierer et al. 2017), the missing links regarding the planning of public health correlated with the green environment needing to consider how it can be best promoted and provide more benefits to public health. Policy makers must reveal the urban planning policies considering the green environment such as the composition of landscaping, freshwater, air quality, public health, trees canopy, parks, etc., to sustain public health (Barnes, Donahue et al. 2019).
Marine and freshwater biology
The cloud of marine and freshwater biology is an interesting and important research area related to microorganisms available in the water, whether surface water or underground water which can be directly contaminated due to climate changes and environmental pollution; this directly affects public health (Kamble 2014). Green environment, freshwater, and public health related research need to be done in the near future because it also has a frequency of nodes both in keywords and category. The ocean has a direct effect on public health (Fleming, Broad et al. 2006). Due to climate change and environmental pollution, microbes and contaminated seafood are consumed by humans and so directly affect human health. Therefore, it is urgent to consider green environments to reduce pollution for marine species, as well as maintain seafood safety to aid the increasing population. Furthermore, marine and freshwater organisms can cause death, injury, or long-term health problems, so is worthy of consideration in future research.
Biotechnology and applied microbiology
Biotechnology and applied microbiology is a very wide field in the world of scientific research and it has a great effect on world development in medical sciences. In this case, researchers focus on cells, gene, genetic, genome, environmental biotechnology, and enzymes. This study reveals that research needs to be done concerning how genomes change due to environmental pollution and its effect on public health, mental stress, and physical activities. Biotechnology and applied microbiology to increase green environments careful the genome modified species. These are also sometimes harmful for human health causing allergies by physical contact with genome modified plants, because genome modified plants during pollination cause pollinate pollution and affecting human health (Key, Ma et al. 2008). Thus, it is necessary for green environments to pay attention to plant species, how it reacts in different seasons, and not only to select the plant species for green environments but also to improve human physical as well as mental health. Female plants also need to be selected because of the large amount of pollinate released by male plants (Cariñanos, Casares-Porcel et al. 2014). In addition, genome modified plants produce new pathogens due to environmental changes, which are harmful for human and animal health (Fontes, Pires et al. 2002).
3.6. Limitations
Although this study has given a pictorial visualization x-ray of the green environmental and public health research areas, this study also has a number of limitations. First, this study visualized based on the selected data of WoS, meaning that in this study only those articles were included which are published in the International Scientific Index (ISI). In addition, in the case of methodology, this study did not distinguish between separate green environments, green urban spaces, blue urban spaces, mental health, and public physical activities.