Current World Environment

South Korea is leading the way in smart cities and nature-based solutions

South Korea has actively explored smart city concepts that incorporate ecological solutions for urban environmental challenges. In Seoul, efforts are underway to establish "forest cities" and promote urban greening for air quality improvement. Research has focused on identifying native plant species that tolerate pollution and absorb PM_2.5 and O₃, such as Dryopteris lacera (Thunb.) Kuntze, Machilus thunbergii Siebold & Zucc.⁹⁸ Additionally, Dracaena trifasciata (Prain) Mabb., Monstera deliciosa Liebm. have shown promise in improving indoor air quality.⁹⁹ The COVID-19 pandemic heightened public awareness of the health benefits of green spaces, accelerating commitments to urban green recovery, with phytoremediation playing a central role. Green audits are essential in assessing the ecological services provided by these green spaces, guiding future investments.

Europe is driving a green recovery through policy integration

While European cities generally have better air quality than their Asian counterparts, they still face significant pollution, primarily from vehicular emissions. The focus in Europe is on integrating phytoremediation into broader urban greening and sustainable mobility policies.

Germany is advancing urban green spaces and biomonitoring

Cities like Stuttgart have integrated green spaces to mitigate air pollution. Research in Germany emphasises the biomonitoring capabilities of specific plant species, using plants as indicators for urban air quality. Lichens like Hypogymnia physodes (L.) Nyl., Xanthoria parietina (L.) Th. Fr, as well as mosses like Pleurozium schreberi (Brid.) Mitt., Hylocomium splendens (Hedw.) Schimp are widely used as bioindicators for pollutants such as heavy metals and SO₂.^99-101 Higher plants, including Trifolium pratense L., are studied for their capacity to accumulate pollutants.¹⁰² The COVID-19 lockdowns led to short-term air quality improvements, reinforcing the need for "green recovery" strategies focused on sustainable transport and increased urban vegetation. Green audits continue to inform policy decisions on where to deploy phytoremediation solutions effectively.

The United Kingdom is pioneering low-emission zones and nature-based solutions

In London, one of the world's most stringent Ultra-Low Emission Zones, the role of urban trees and green walls in improving air quality has gained growing recognition. Urban trees such as Quercus robur L., Fagus sylvatica L., and Pinus sylvestris L. play a crucial role in capturing particulate matter and enhancing microclimates. Post-COVID recovery plans in the United Kingdom emphasise creating greener, more walkable cities, aligning with phytoremediation strategies. Green audits help identify areas where green infrastructure can have the greatest impact on air quality, especially in pollution hotspots.¹⁰³

North America is driving research and policy innovation for sustainability

North American cities are increasingly recognising the health and environmental benefits of urban greening, with ongoing research into the mechanisms and effectiveness of phytoremediation.

The United States is enhancing urban forests for air quality benefits

In cities like New York and Chicago, extensive urban forestry programs have contributed significantly to air quality improvement. Studies in the United States have quantified the amount of air pollutants removed by urban trees such as Quercus alba L., Pinus strobus L., Acer saccharum Marshall, demonstrating their ability to filter particulate matter, O₃, NO_x, and SO₂.^104-106 The COVID-19 pandemic highlighted the potential for cleaner air due to reduced vehicular traffic, spurring discussions on how urban planning and green infrastructure, including phytoremediation, can support a healthier urban recovery. Green audits help assess the ecological benefits of existing and planned green spaces.¹⁰⁵

Canada is advancing green infrastructure for sustainable cities

In cities like Toronto and Vancouver, green infrastructure is central to climate resilience and sustainability. Phytoremediation by trees like Pinus L., Quercus L., and Populus L. are being explored in various urban greening projects, including green roofs and living walls, especially for mitigating VOCs and PM.¹⁰⁶ The emphasis on urban green recovery post-COVID has further spurred investments in nature-based solutions, recognising their multifunctional benefits for air quality, biodiversity, and mental well-being. Green audit frameworks help integrate these solutions into broader municipal planning.

South America is tackling pollution from industrialisation

South American cities, particularly those undergoing rapid industrialisation, face significant air pollution challenges. Phytoremediation offers a low-cost, sustainable solution to these issues.

Brazil is utilising bioremediation for contaminated urban areas

In Brazil, especially in cities like São Paulo, air pollution from vehicular traffic and industrial emissions is a major concern. Ongoing research into the use of native plants such as Calophyllum brasiliense Cambess., Hymenaea courbaril L., Protium heptaphyllum (Aubl.) Marchand for phytoremediation of heavy metals and airborne PM is promising.¹⁰⁷ The pandemic highlighted the socio-economic disparities influencing environmental health, driving the adoption of green recovery initiatives that prioritise equitable access to green spaces and cleaner air. Green audits are critical for identifying high-pollution areas where phytoremediation interventions can have the greatest impact.

Colombia-urban greening and community engagement

Bogotá, Colombia, has gained international recognition for its commitment to urban greening and sustainable transportation. While public transport improvements are a priority, the role of trees like Populus deltoides W. Bartram ex Marshall and Salix babylonica L. is increasingly emphasised for air quality improvement.¹⁰⁸ Post-pandemic, there has been a surge in community-led greening projects, fostering grassroots adoption of phytoremediation as part of broader green audit and recovery strategies.

Africa is exploring emerging solutions for rapid urbanisation

African cities are facing unprecedented rates of urbanisation, often accompanied by escalating air pollution. Phytoremediation presents a cost-effective, accessible solution.

South Africa is addressing mining impacts through ecological restoration

In cities like Johannesburg, mining activities contribute to significant heavy metal and dust pollution. Phytoremediation research is focusing on indigenous species such as Searsia longipes (Engl.) Moffett, Syzygium guineense Wall., Ficus craterostoma Warb. ex Mildbr. & Burret to remediate contaminated soils and air.¹⁰⁹ The pandemic underscored the vulnerability of urban populations to respiratory illnesses, intensifying the need for sustainable air quality interventions. Green recovery plans focus on ecological restoration and the development of green spaces as natural air filters. Green audits are essential for identifying areas most in need of intervention.

Nigeria is advancing waste management and green infrastructure

In Lagos, Nigeria’s largest city, severe air pollution exacerbated by poor waste management and industrial emissions calls for innovative solutions. Although large-scale phytoremediation projects are still in their infancy, research into local plants like Ficus religiosa L., Pongamia pinnata (L.), etc., for air purification is gaining momentum.¹¹⁰ The pandemic accelerated discussions on urban green recovery, emphasising the role of nature-based solutions. Green audits are vital for mapping pollution sources and identifying areas that can benefit most from phytoremediation.

Table 1: Seasonal variation in PM deposition^{96-97, 99-106}

Indian context: Localised challenges and opportunities for phytoremediation

India's air pollution mitigation efforts, including the (NCAP),¹¹¹ Smart Cities Mission, Green India Mission (GIM), and National Afforestation Programme (NAP), can synergistically integrate phytoremediation. Private sector initiatives also contribute to urban greening. Successful large-scale adoption hinges on grassroots engagement: empowering local communities, incentivising farmers for "green farming," and strategically involving urban planners in zoning, green infrastructure design, green audits, and capacity building for effective, sustainable air quality improvement. However, India faces an unprecedented urban air quality crisis, with 9 of the world's 10 most polluted cities often being Indian.¹¹² This necessitates a robust and multi-pronged approach, where phytoremediation can play a crucial, complementary role.

Delhi is battling hazardous air through green initiatives

Delhi consistently ranks among the world's most polluted capital cities, experiencing alarmingly high levels of PM_2.5 during the winter months.^113-115 Studies in Delhi have explored the efficacy of various tree species in capturing particulate matter and absorbing gaseous pollutants. Research by TERI (The Energy and Resources Institute) and other institutions has identified species like Azadirachta indica A. Juss., Ficus religiosa L., Saraca asoca (Roxb.) Willd, Terminalia arjuna (Roxb.) Wight & Arn. as effective air purifiers, demonstrating their ability to reduce PM_2.5 concentrations in urban areas.^116,117 Vertical gardens and green walls are also being piloted in areas with high traffic density. For instance, the Delhi government's efforts to increase green cover, though not explicitly labelled as phytoremediation projects, inherently leverage this technology. The temporary air quality improvements during the COVID-19 lockdowns in Delhi further highlighted the potential for reduced emissions and subsequent gains from increased green cover.

Kolkata greening for resilient urban environments

Kolkata, another densely populated Indian metropolis, faces significant air pollution challenges from industrial emissions, vehicular traffic, and open burning. Research in Kolkata has focused on identifying local plant species suitable for phytoremediation, like Ficus religiosa L., Mangifera indica L., and Polyalthia longifolia Sonn. B. Xue & R. M. K. Saunders, Eucalyptus globulus Labill., Ficus benghalensis L., Azadirachta indica A. Juss., particularly those tolerant to heavy metals and PM. Studies have highlighted the role of urban trees in sequestering carbon and capturing airborne pollutants.¹¹⁸ Initiatives to develop green corridors and expand urban parks are slowly incorporating the principles of phytoremediation, aiming to enhance air quality and biodiversity. The city's post-COVID-19 urban green recovery plans emphasise sustainable mobility and expanding green spaces to create a more resilient urban environment.

Mumbai: Coastal dynamics and green solutions

Mumbai, a coastal megacity, faces unique air pollution dynamics influenced by sea breeze and vehicular emissions. Research is exploring the role of coastal vegetation, including mangroves, in air filtration and carbon sequestration. Studies have evaluated various plant species like Ficus religiosa L., Azadirachta indica A. Juss., Mangifera indica L., Polyalthia longifolia Sonn. B. Xue & R. M. K. Saunders for their efficacy in trapping PM and absorbing gaseous pollutants in the city's specific climatic conditions.¹¹⁹ Efforts to increase urban green cover, including the development of new parks and green spaces, are being seen as vital for improving air quality and public health. The push for urban green recovery after the pandemic has brought renewed focus on incorporating nature-based solutions, including phytoremediation, into Mumbai's urban development agenda.

Methodology

The methodology of this study followed the PRISMA protocol to ensure a transparent, systematic, and reliable review process. Comprehensive searches were conducted across major academic databases, including Google Scholar, PubMed, ScienceDirect, Web of Science, NCBI, and ResearchGate, as well as official reports from NCAP, the GIM, the UN SDGs framework, and other government publications. The search covered literature published between 2010 and 2025, with particular emphasis on recent studies from 2021 to 2025. Keywords such as “phytoremediation and air pollution,” “urban air quality,” “green audit,” “green recovery,” “indoor plants air purification,” and “COVID-19 and environment” were used to identify relevant research, resulting in an initial pool of 2,849 records. After removing duplicates, 1,927 unique studies underwent title and abstract screening based on inclusion criteria related to plant-based removal of airborne pollutants, phytoremediation mechanisms, indoor and outdoor air-purifying species, and urban environmental improvement. Studies focused solely on soil or water remediation, lacking scientific evidence, or unrelated to air quality were excluded, leaving 312 articles for full-text assessment. Each article was evaluated for scientific quality, methodological clarity, and relevance to pollutant mitigation (PM, CO₂, NO₂, CO, SO₂, VOCs, and heavy metals), plant-based uptake mechanisms, urban greening efforts, or SDG-linked strategies. Ultimately, 156 high-quality sources met the eligibility criteria and were analysed to identify major themes such as pollutant types, limitations of mechanical systems, post-COVID developments, effective plant species, phytoremediation pathways, global and Indian case studies, SWOC insights, and future directions. This PRISMA-based approach ensured that the study’s findings are grounded in robust evidence and accurately reflect current global trends in phytoremediation and sustainable air-quality management.

Results and Discussion

The global literature provides a clear and detailed understanding of phytoremediation as an effective nature-based method for reducing urban air pollution. Studies from different regions show that plant species vary in their ability to capture or absorb pollutants such as PM, CO₂, NO₂, O₃, VOCs, and heavy metals. In Asia, especially China, large greening efforts such as urban forests and green belts have reduced PM_2.5 and NO₂, supported by species of Populus L. and Salix L.⁹⁶ South Korea’s smart-city projects also report good results using species such as Dryopteris lacera (Thunb.) Kuntze and Machilus thunbergii Siebold & Zucc., which help reduce PM_2.5 and O₃.⁹⁸ European studies add value by using lichens and mosses, such as Hypogymnia physodes (L.) Nyl., Xanthoria parietina (L.) Th. Fr., and Pleurozium schreberi (Brid.) Mitt.—to monitor SO₂ and metal pollution, while also contributing to local pollutant reduction.^100–102 Research in North America shows that trees such as Quercus alba L., Pinus strobus L., and Acer saccharum Marshall significantly lower PM, O₃, NOx, and SO₂ levels.^104–105 Work from South America and Africa highlights the usefulness of native species like Calophyllum brasiliense Cambess., Hymenaea courbaril L., and Searsia longipes (Engl.) Moffett for pollution from traffic, mining, and industry.^107–110 Overall, global studies confirm that phytoremediation is a practical, flexible, and scalable solution for improving air quality.

In India, the literature shows both severe air quality issues and strong potential for phytoremediation. Many Indian cities—such as Delhi, Kolkata, Mumbai, Kanpur, and Lucknow—experience very high levels of PM_2.5, PM₁₀, NO₂, and SO₂ due to traffic, industry, biomass burning, construction dust, and seasonal factors.^111–115 Indian studies identify effective plant species such as Azadirachta indica A. Juss., Ficus religiosa L., Mangifera indica L., Polyalthia longifolia Sonn., and Eucalyptus globulus Labill., which efficiently trap PM and absorb gases like NO₂, CO, and VOCs.^116–119 Research from Delhi shows that Ficus benghalensis L. and Saraca asoca (Roxb.) Willd. capture large amounts of PM, while coastal species such as Avicennia marina (Forssk.) Vierh. help in CO₂ storage and pollutant reduction in Mumbai. Indian studies also highlight the role of leaf surface features, stomatal patterns, and biochemical properties in determining how well plants remove pollutants. National programmes such as NCAP, the GIM, and the Smart Cities Mission recognise the importance of greening for air quality, although challenges remain in selecting suitable species, planning green spaces, and ensuring long-term maintenance.^111–112 Overall, the Indian evidence shows that phytoremediation is a feasible, low-cost, and effective option to support cleaner and healthier urban environments.

Mechanism of phytoremediation

The underlying mechanisms of phytoremediation are based on the physiological, biochemical, and molecular pathways that enable plants to absorb, detoxify, and metabolise air pollutants. These mechanisms are not only fundamental to plant survival but are also highly effective in removing environmental pollutants.

CO₂, a major greenhouse gas, is naturally absorbed by green plants during photosynthesis, specifically via the Calvin–Benson cycle, which is a light-independent set of reactions occurring in the chloroplasts. During this cycle, CO₂ is fixed by the enzyme Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and transformed into glucose and other carbohydrates. These sugars are further metabolised through glycolysis and the Krebs cycle, producing ATP and NADH, which serve as the primary energy sources for various cellular processes, including growth, repair, and stress tolerance. Thus, CO₂ is effectively converted into non-toxic organic molecules, contributing not only to atmospheric CO₂ reduction but also to biomass accumulation.^120-123 Experimental studies using Spinacia oleracea L. have demonstrated that this plant efficiently assimilates CO₂ and utilises it within its internal biochemical processes, thereby reducing the pollutant load in the atmosphere while promoting its own growth (Figure 1).^120,121

NO₂ is a highly reactive gaseous pollutant commonly released through the burning of fossil fuels and industrial emissions. It plays a key role in the formation of acid rain and tropospheric O₃, and is known for causing respiratory disorders in humans. However, certain plants have evolved efficient metabolic pathways to neutralise and convert NO₂ into usable nitrogen compounds.

The GS-GOGAT cycle is the central pathway involved in NO₂ detoxification. This includes GS: Converts NH₄⁺—produced from absorbed NO₂—into glutamine using ATP and GOGAT: Catalyses the conversion of glutamine and a-ketoglutarate into two molecules of glutamate.

These amino acids are essential building blocks for protein synthesis and contribute to the nitrogen economy of the plant. The entire pathway also supports the plant’s redox balance and energy metabolism via the generation of ATP and NADP⁺. Research using Arabidopsis thaliana (L.) Heynh. has confirmed that NO₂ exposure induces the expression of genes encoding GS and GOGAT, supporting the view that plants are capable of actively assimilating NO₂ into their metabolic systems, thereby detoxifying this pollutant in a biologically beneficial way (Figure 2).^120-123

Figure 1: Mechanism of CO2 absorption and utilisation in plants through photosynthesis and metabolic pathways Click here to view Figure

Figure 2: Mechanism of NO? absorption in plants by metabolic pathways. Click here to view Figure

In addition to CO₂ and NO₂, plants have also demonstrated the ability to remediate other harmful airborne pollutants such as CO, VOCs, and PM. Each of these pollutants poses distinct risks to environmental and human health, and plants combat them through a variety of physiological, biochemical, and physical mechanisms. Certain plant species are capable of absorbing CO₂ through their stomata and breaking it down via enzymatic oxidation. Enzymes such as catalase and peroxidase help in oxidising CO into CO₂, which is then assimilated through the Calvin cycle for energy production. Indoor plants like Spathiphyllum wallisii Regel have been shown to significantly reduce CO levels in closed environments,⁶⁶ while outdoor species like Hibiscus rosa-sinensis L. are also found effective in open urban settings.^67,68

VOCs are a diverse group of chemicals released from paints, cleaning agents, industrial solvents, and household products. Exposure to VOCs can cause headaches, respiratory issues, and even long-term neurological damage. Plants absorb VOCs mainly through their stomata, followed by internal detoxification through metabolic processes. Inside plant tissues, VOCs are broken down enzymatically or stored in vacuoles, and in some cases, the rhizospheric microbes also assist in degradation. Schefflera arboricola Hayata, and Opuntia microdasys (Lehm.) Pfeiff is are popular indoor species known for its capacity to reduce VOC concentrations. ^124,125 Similarly, outdoor plants like Phyllostachys edulis (Carrière) J.Houz. and Ilex rotunda Thunb. have demonstrated considerable efficiency in absorbing VOCs in urban green belts and roadside plantations.^71-73

PM, particularly PM_2.5 and PM₁₀, is a significant air pollutant that can carry harmful substances like heavy metals and PAHs. Plants mitigate PM through physical entrapment and biochemical detoxification. Leaves with high surface area and rough textures trap particles, while biochemical responses, such as the activation of superoxide dismutase, peroxidase, and catalase, neutralise oxidative stress from deposited particles. Indoor plants like Chlorophytum comosum (Thunb.) Jacques (Spider plant) and Sansevieria trifasciata (Prain) Mabb. (Snake plant) trap fine particles and degrade organic components of PM, while outdoor species like Mangifera indica L., Trifolium pratense L. reduce PM levels in polluted urban areas.^63,64,75,126

Ecological and practical relevance of phytoremediation

Phytoremediation stands out as an ecologically sustainable and practically viable approach to air pollution control, offering a self-regulating and energy-efficient alternative to conventional mechanical purification systems. Unlike air purifiers that demand electricity, regular maintenance, and periodic filter replacements, plants operate autonomously—absorbing, metabolising, and neutralising pollutants as part of their intrinsic physiological processes.^74,124,125 The integration of phytoremediating species into urban landscapes, green buildings, and indoor environments not only enhances air quality but also adds aesthetic, psychological, and biodiversity benefits, making them indispensable components of nature-based urban design.⁷¹

Through carbon sequestration via the Calvin cycle and N assimilation via the GS-GOGAT pathway, plants mitigate major greenhouse gases like CO₂ and NO₂.^120-123 Their adaptive capacity to also filter out harmful pollutants such as CO, VOCs, and PM underscores their multifunctional detoxifying potential.^63-66 This remarkable versatility positions phytoremediation as a powerful tool for addressing contemporary environmental challenges, including urban smog, climate change, and ecological degradation. When thoughtfully incorporated into green infrastructure and environmental policy, phytoremediation offers a low-cost, long-term, and scalable solution to restoring air quality and promoting public health in both urban and rural contexts.

Alignment of phytoremediation with Sustainable Development Goals

Phytoremediation, a plant-based approach to air pollution mitigation, directly supports several UN SDGs by naturally absorbing airborne pollutants. It contributes significantly to UN SDG 3 (Good Health and Well-being) by reducing harmful substances like CO, NOx, VOCs, and PM, thereby mitigating health risks and promoting public well-being in polluted regions.^22,74 For UN SDG 11 (Sustainable Cities and Communities), phytoremediation enhances urban liveability and ecological resilience by improving air quality in both indoor spaces (e.g., against VOCs) and outdoor environments through roadside plantations and green belts.^71,124,125 Furthermore, it aligns with UN SDG 13 (Climate Action) by absorbing CO₂ during photosynthesis and offering a low-energy, emission-free alternative to mechanical filtration, thus aiding in climate change mitigation.^120,122 This makes phytoremediation a critical tool for building a greener, healthier planet.

Strengths-Weaknesses-Opportunities-Challenges analysis of phytoremediation

Strengths

Phytoremediation harnesses the natural metabolic processes of plants to effectively absorb, degrade, or sequester harmful pollutants. This green technology inherently avoids the production of secondary pollutants, a common issue with some conventional methods. Beyond direct pollutant removal, many phytoremediating plants contribute significantly to broader ecological benefits, including habitat creation and support for urban biodiversity, regulation of microclimates, and even enhancing mental health and well-being for urban residents.⁷⁴ Specific species demonstrate strong pollutant specificity; for instance, Mangifera indica L. is highly effective in capturing particulate matter, while Spathiphyllum wallisii L. is recognised for its capacity in CO removal.^69,70

Weaknesses

Despite its numerous merits, phytoremediation possesses inherent limitations. Many species are capable of targeting only a narrow range of pollutants, and the overall process is relatively slow, rendering it unsuitable for rapid remediation in heavily polluted or acute contamination zones. Furthermore, plant growth and, consequently, pollutant uptake are significantly influenced by climatic and seasonal factors, which can markedly reduce effectiveness during extreme weather conditions or specific seasons. For instance, deciduous trees are less effective during the winter months. Addressing this, research into engineered plants with enhanced year-round functionality offers a potential solution to mitigate seasonal efficiency fluctuations. The need for sufficient space, water, and light can also restrict the widespread deployment of phytoremediation in highly congested urban areas.^124,125 Moreover, successful long-term phytoremediation requires meticulous species selection and consistent maintenance.

Opportunities

Significant opportunities exist to expand the application of phytoremediation through both biotechnological advancements and ecological innovation. The development of genetically engineered plants with multi-pollutant absorption capacities holds immense promise, as it could greatly increase the scope and efficiency of air purification. For example, a single engineered plant could potentially combine the robust particulate matter absorption traits of Mangifera indica L. with the substantial oxygen-releasing capabilities of Eucalyptus viminalis Labill.^69,70 Additionally, integrating plants with pollutant-degrading microbial communities within the rhizosphere could accelerate pollutant breakdown and enhance overall plant resilience.¹²⁷ Beyond scientific advancements, urban planning strategies can be optimised by precisely matching plant species to local pollution profiles. Crucially, there are substantial opportunities for partnerships with large-scale urban development projects, which can integrate phytoremediation as a fundamental component from the planning stages. Collaboration with eco-tourism initiatives and the corporate sector (through corporate social responsibility programs or direct investment) can also provide vital funding and resources for implementing extensive phytoremediation projects, transforming urban green spaces into living air purifiers.

Challenges

Phytoremediation faces several formidable challenges that impede its broader implementation. There is generally limited public awareness regarding its efficacy, coupled with a lack of standardised implementation protocols and insufficient dedicated funding for large-scale applications. In many regions, the research and development in this domain remain underdeveloped, and crucially, urban planners may lack the specific training required to effectively select, deploy, or manage phytoremediating species. While theoretically low-maintenance, large green areas still necessitate consistent irrigation, pruning, and vigilant monitoring to ensure optimal performance. Furthermore, existing regulatory barriers and fragmented policy frameworks often hinder the seamless integration of phytoremediation into mainstream environmental planning initiatives.⁷² The sheer scale of implementation, particularly in densely populated or heavily industrialised regions, presents a considerable challenge, requiring comprehensive planning and sustained commitment to overcome spatial and logistical constraints.

Future prospects of phytoremediation

The future of phytoremediation holds immense promise, particularly through advanced technological integration and collaborative implementation strategies. These advancements are crucial for effectively addressing urban air pollution, especially as cities globally look towards urban green recovery strategies in the wake of events like the COVID-19 pandemic, which highlighted the critical link between environmental health and public well-being. This renewed focus on green recovery provides a strong impetus for integrating phytoremediation and green audit principles into future urban development.

Advancements in genetically engineered plant development

Significant progress in genetic engineering will be pivotal for enhancing pollutant uptake efficiency in plants. If plants can be genetically modified to express genes responsible for absorbing multiple types of pollutants, they can be deployed more broadly. For example, plants that absorb both PM and VOCs would be highly valuable in urban industrial zones.^69,70 These innovations promise to significantly improve phytoremediation's effectiveness without requiring increased land area or plant density, offering a high-impact solution within existing urban footprints. A potential roadmap for achieving these advancements involves several sequential phases. It would begin with foundational genomic research to identify and characterise key genetic pathways governing multi-pollutant absorption and stress tolerance in plants. This would be followed by the development and rigorous testing of genetically engineered prototypes in controlled laboratory and greenhouse environments, ensuring both efficacy and ecological safety. Subsequently, controlled field trials in isolated urban settings would be conducted to meticulously monitor performance, pollutant removal rates, and any potential environmental impacts. The final phase would involve large-scale deployment, contingent upon comprehensive regulatory approvals and widespread public acceptance, informed by transparent communication and engagement.

Site-Specific plant selection and integration with microbial communities for enhanced ecosystem function

Future phytoremediation efforts will increasingly prioritise customised, site-specific plant selection based on detailed local pollution profiling. For instance, roadsides with high dust and vehicular pollution may benefit from dense, PM-absorbing plants like Ficus religiosa L., while industrial zones emitting NO₂ and VOCs could strategically utilise species like Arabidopsis thaliana (L.) Heynh.^123-125 This precision-driven approach will ensure targeted pollutant removal and optimised land use. Furthermore, combining plants with beneficial soil microbial communities is poised to dramatically enhance pollutant degradation. Microbes in the rhizosphere can effectively metabolise heavy metals and various organic pollutants, concurrently supporting plant health and accelerating the overall remediation speed. Such plant-microbe synergies are rapidly gaining traction in research and offer a highly scalable method to boost the performance of existing phytoremediation systems.¹²⁷ The roadmap for integrating plant-microbe synergies involves stages from identifying and optimising specific plant-microbe combinations for various pollutant types and diverse environmental conditions, to the development of standardised, commercially viable bio-inoculants and cultivation protocols suitable for large-scale urban applications. The final stage would involve the implementation of pilot projects in diverse urban settings, continuously refining techniques and demonstrating scalability for broader adoption.¹²⁸

Remodelling strategies and collaborative governance for sustainable development

The effectiveness and impact of phytoremediation can be significantly enhanced through strategic remodelling of deployment methods. Expert-driven planning that incorporates advanced pollutant dispersion modelling, precise species selection, and innovative landscape engineering can transform phytoremediation from a passive approach into a highly active, targeted environmental tool. Sites such as industrial zones, post-mining abandoned areas, major highways, and underutilised urban rooftops can be transformed into high-impact remediation zones when structured strategies are applied.¹²⁹

For phytoremediation to achieve a broad city-wide impact, collaboration among diverse stakeholders is crucial. Urban planners, scientists, and local governments must work synergistically.¹³⁰ Urban planners can integrate phytoremediation into master plans, zoning regulations, and green infrastructure designs to ensure the strategic placement of air-purifying vegetation. Scientists provide invaluable expertise in plant selection, genetic research, biomonitoring, and performance validation, while local governments play a pivotal role in policy enforcement, funding allocation, and facilitating public participation.¹³¹

The COVID-19 pandemic has accelerated the need for urban green recovery, highlighting the importance of these collaborations. Green audits can be essential tools in systematically assessing the environmental performance of urban areas, identifying pollution hotspots, and determining the most effective locations for new phytoremediation-based interventions. By employing a data-driven approach, greening efforts will be precisely targeted, ensuring maximum air quality benefits and contributing to more sustainable, resilient urban environments.¹³²

Governmental support and public engagement

For phytoremediation to be truly impactful and scaled across cities, robust governmental support and sustained civic participation are essential. Governments can play a crucial role by enforcing anti-deforestation laws, incentivising urban greening projects, mandating tree planting on barren or underutilised lands, and running comprehensive public awareness campaigns. Educational institutions can contribute significantly by integrating phytoremediation concepts into environmental science curricula, fostering long-term environmental stewardship among future generations. Furthermore, fostering robust public-private partnerships and leveraging Corporate Social Responsibility (CSR) initiatives can unlock vital funding and resources for large-scale green infrastructure projects.^133,134 This holistic approach, integrating scientific innovation, strategic planning, and collaborative governance, promises to unlock the full potential of phytoremediation for healthier, more sustainable urban environments.¹³⁵

Interdisciplinary approaches

Addressing urban air pollution effectively necessitates a truly interdisciplinary approach, integrating phytoremediation with diverse fields. From an environmental psychology perspective, the presence of green spaces, enhanced by phytoremediation, extends beyond mere pollution abatement to significantly improve mental well-being, reduce stress, and foster a stronger connection to nature among urban dwellers.^136,137 This psychological benefit strengthens the case for widespread green infrastructure adoption. In urban design, plants can be seamlessly integrated into architectural elements, creating living facades, green roofs, and vertical gardens. These designs not only provide aesthetic value but also actively purify air, regulate building temperatures, and enhance biodiversity. This integration transforms passive structures into active environmental assets. From an environmental law standpoint, robust policy frameworks are essential to promote and mandate the inclusion of green technologies like phytoremediation in urban development. This includes developing regulations for green building standards and land-use planning that prioritise ecological solutions. The push for urban green recovery post-COVID-19 offers a unique opportunity to embed these interdisciplinary perspectives, leveraging green audits to identify optimal integration points for phytoremediation within holistic urban planning strategies, driving sustainable development.¹³⁷

Policy and public engagement

The successful city-wide implementation of phytoremediation heavily depends on strong government policies and active public engagement. Governments have a critical role in fostering green infrastructure through specific policy recommendations. These could include offering incentives to developers to integrate extensive green spaces and phytoremediation systems into urban projects, such as tax breaks or expedited approval processes. Additionally, direct grants for establishing and maintaining urban green spaces, especially those using effective phytoremediation species, would help accelerate the adoption of these practices.

For instance, the (NCAP) could be expanded to include specific targets and funding mechanisms for phytoremediation.^111,138 Alongside top-down policies, public engagement is essential. Community-driven initiatives, such as neighbourhood greening programs, school gardens, and citizen-led tree-planting campaigns, can make a significant impact on urban greening projects. Public awareness can be raised through targeted educational campaigns, workshops, and media outreach, highlighting the health benefits and ecological services that urban plants provide.¹³⁹

Governments could also mandate tree planting and maintenance in urban areas, ensuring strict enforcement, especially in densely populated regions. The message could be framed around engaging citizens with mottos like, "Claim your own oxygen – plant at least one tree today," or "Plant a tree, secure your city’s future!" The awareness of environmental health, heightened by the COVID-19 pandemic, has paved the way for promoting urban green recovery. These efforts, underpinned by green audits, can demonstrate measurable improvements in air quality and overall environmental health.^140-142

Conclusion

Phytoremediation offers a transformative solution to improve air quality, public health, and long-term environmental sustainability by leveraging the natural purifying ability of plants. This nature-based approach addresses immediate pollution challenges while enhancing ecosystem resilience and safeguarding future generations. Understanding plant-pollutant interactions is crucial for expanding phytoremediation’s global application, as seen in initiatives like India’s GIM, Nagar Van Yojana. To fully unlock its potential, a collaborative effort between urban planners, policymakers, and the public is necessary. Key strategies include integrating phytoremediation into urban planning, incentivising green infrastructure, and fostering public engagement. Protecting mature trees, which offer vital ecological services, is equally essential. In cities like Delhi and Kolkata, a “Green Lung Initiative” focused on creating green corridors, community parks, and incorporating green infrastructure in transportation hubs could significantly reduce pollution, with success tracked through air quality monitoring.

In essence, these initiatives promise to create resilient, vibrant, and healthier urban environments, ensuring sustainable air quality for future generations. Phytoremediation can transform cities into greener, healthier spaces, providing a long-lasting positive impact on urban ecosystems and public well-being.

Acknowledgment

The authors wish to acknowledge the Department of Botany at the University of Burdwan in Burdwan, West Bengal, India, for their essential assistance and contributions.

Funding Sources

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Conflict of Interest

The authors do not have any conflict of interest.

Data availability statement

In order to prepare this paper, the writers employed secondary data. These data's source references have been properly cited. The information is accessible online through resources including NCBI, Research Gate, and Google Scholar. The corresponding author has access to these data and will make them available upon reasonable request.

Ethical Statement

This research did not involve human participants, animal subjects, or any material that requires ethical approval

Informed Consent Statement

This study did not involve human participants, and therefore, informed consent was not required

Permission to reproduce material from other sources

Not Applicable

Author Contribution

Soudip Das: Methodology, Resources, Writing (original draft), Writing (review and editing).

Ayan Saha: Methodology, Resources, Review, Editing, Data Curation, and Format analysis

Dibyendu Saha: Corresponding author, Conceptualisation, Methodology, Supervision, Validation, Review and editing.

Kushal Roy: Data Curation, Format analysis, Review, and Editing.

Md Nazir: Data Curation, Review.

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Abbreviations List