In recent years, researchers have focused their efforts on determining the causes of urban environmental pollution. We examined the relationship between urban environmental pollutant emissions and migrant populations at the prefectural level to determine whether migrant populations have a significant impact on urban environments.

Our study's main findings were as follows:

• The size and density of migrant populations have a significant impact on environmental emissions. Migrant populations, in particular, have a negative impact on the Air Quality Index (AQI) and PM2.5 emissions while having a positive effect on NO2 and CO2 emissions.
• Migrant populations had an 8 to 30 times lower impact on urban environmental air pollutants than local populations.
• Urban environmental pollutant emissions differ significantly throughout cities due to differences in industrial structures, public transportation facilities, and population densities.

Legitimacy in policy enforcement is a strong predictor of policy success. Growing demand for green cities, combined with increased transparency in governance, will reduce pollution and traffic congestion.

Introduction
Air pollution is not merely a nuisance and a threat to health. It is a reminder that our most celebrated technological achievements- the automobile's, the jet plane , the power plant, industry in general, and indeed the modern city are, in the face of environmental failure[1]

Human history has frequently seen people moving from one place to another in need of better economic prospects. People migrate to access these new opportunities while certain locations and industries remain behind in terms of their ability to support populations. Due to a shift in the labour into industrialising areas, industrialization widens the gap between rural and urban communities.

The reasons that lead populations to change from those that emphasise individual rationality and household behaviour to those that relate to the unit of capitalist development are the subject of significant debate.

Air pollution is the world's leading single environmental health risk, impacting not only people's mental and physical health, but also one's subjective well-being. People should first take measures to safeguard themselves, such as restricting their outdoor activities, acquiring protective equipment, and even choosing to emigrate away from heavily polluted cities as pollution levels increase. The latter brings public and academic focus on the phenomenon of migration caused by environmental pollution.

Citizens who have spent their entire lives in the Delhi-NCR region have made the difficult decision to relocate in past years, as concern regarding air pollution has grown. However, this phenomenon appears to be limited to the billionaire class. In fact, according to a recent online survey carried out by The Economic Times[2], 78% of the 2,272 respondents cited "high levels of pollution" as the main reason for wanting to evacuate India's metropolitan cities; 30% needed to end within five years, and another 26% were simply waiting for the right job to come along.

This year, a Pollution Coping Survey was conducted to evaluate residents' reactions to the region's air pollution levels. More than 17,000 participants reacted, with 40% simply stating they would much rather leave Delhi-NCR and relocate elsewhere to avoid the toxic air. The decision to migrate due to pollution has risen from 35% in the past year's survey, with this being dependent on the capacity to find work elsewhere.

But to Trace the people of India whether they will migrate or not due to Air pollution is a very difficult task because there are major benefits to live in urban area as comparison to rural area because there are more economic benefit of living in big cities as well as more job opportunity, more profit generation, better medical and health facilities, superior infrastructure which make them adjust to even in higher polluted cities.

These factors actually create huge in-migration flows into such areas, in which economic growth is a swap for pollution-related harms .However due to toxicity in the polluted environment, People have assumed that the economic benefits presented by polluted cities are not worth the cost to their wellbeing and the future of their children.

As the cluster of "Pollution Refugee" or "Air pollution Migrants" has been growing slowly, speedily and even causing permanent disaster to the urban people- voyage with a better quality of air and life.

Researchers around the world had noticed that air pollution and environmental degradation have a vast impact on people to migrate from one place to another in search of better health and there is a huge impact on outflows and inflows of people to migrate and in this context China is a notable example, where Beijing declared a "war on pollution" following high-profile global coverage of the 2013 "apocalypse."

According to a 2017 study conducted in China by the National Bureau of Economic Research [3] , amidst regulatory barriers on migration and its rising costs, there has been an increase in human mobility with increasing air pollution. It was noticed that a county with a 10% increase in air pollution over the duration of a year would experience a 2.7% decrease in population.

A few surveys from the Czech Republic confirm the critical effects of air pollution on immigration levels, demonstrating that air pollution can become a big threat, driving out-migration or blocking in-migration. Another empirical study conducted at the regional governments in Italy suggested that environmental pollution has started to occur in the future in the public domain, and that it will eventually cause larger human outflows to places with a higher quality of life.

India is particularly susceptible to the consequences of climate change, with nearly 68% of the country vulnerable to drought, 60% sensitive to earthquakes, and 75% helpless to cyclones and tsunamis. These physical factors, associated with the country's large population density, poverty levels, rapid population growth, and ecological pollution, make it the country most vulnerable to disaster-related damage and displacement in South Asia.

However, there is little awareness of the impact of climate change on human mobility in India, and there is a significant gap in policies at the national and state levels at the crossroads of climate change and migration.

Process Of Air Quality To Be Monitored

Air quality is an important concern in India. Understanding real-time air quality has therefore become a societal requirement. The National Ambient Air Quality System (NAAQS), which supervises pollutants, allows for this. Particulate Matter (PM10 and PM2.5), Sulphur Dioxide, Nitrogen Dioxide, Ammonia, Carbon Monoxide, Ozone, and Benzene are tested at 49 monitoring stations throughout the Delhi NCR, 2019 [4]

This information from genuine monitors allows authorities to recognise long-term trends, display data in minutes, issue warnings during critical times, and develop action plans to meet norms (CPCB, 2019). A complex mixture of thousands of pollutants causes air pollution. The WHO Worldwide Air Quality Guidelines provide global advice on key air pollutants that are dangerous to human health [5] . Particulates (PM), ozone (O3), nitrogen dioxide (NO2), and sulphur dioxide (SO2) are illustrations (WHO, 2021). WHO guidelines, initially established in 2005, were recently updated in 2021 to reflect how even low levels of pollutants can have serious health effects.

Air pollution is the single greatest threat to human health, according to the World Health Organisation, provoking an estimated 7 million premature deaths globally each year (WHO, 2021). Particulate Matter (PM) is a common sign of air pollution. It has a greater effect on individuals than other pollutants, and even at very low levels, it has brief health consequences.

The World Health Organisation (WHO) has reported that 4.2 million people die annually due to air pollution and most of these deaths occurred in developing countries [6] . The major air pollutants that define the air quality over a region are carbon monoxide (CO), sulphur dioxide (SO2), nitrogen oxides (NOx), volatile organic compounds (VOCs), ozone (O3) and respirable particulate matter.

Epidemiological and toxicological studies reported that these pollutants can induce various respiratory and cardiovascular diseases like nose and throat irritation, bronchial inflammation, epithelial damage, childhood asthma, lung inflammation and dyspnoea and can enhance mortality and morbidity. Moreover, particulate matter with a diameter less than 10 �m was able to reach the upper respiratory tract.

Brain Drain Of Polluted Cities

The far-reaching consequences of polluted air require government intervention to safeguard community well-being. China [7], European countries [8], and the United States [9] have imposed air pollution regulations and prevention policies. Although a variety of laws are in place, previous studies have shown mixed results because of the limited effectiveness of environmental regulations and unfulfilled desired air pollution control goals.

Despite the fact that legal provisions are in place, the race for wealth creation has exacerbated an already bad air pollution situation. As a consequence, in addition to initiatives, individuals are actively seeking a variety of ways to minimise the effects of pollution. Residents may buy particulate-filtering face masks [10] , prefer short-term avoidance travel and leisure - time activities, and save themselves from outdoor activities.

Another potential precaution is cross-national movement of people, which takes place when individuals move from heavily polluted countries to clean and efficient ones. The brain drain effect occurs when highly skilled workers leave their current jobs, interrupting the transfer of intellectual capital. For more than 50 years, scientists have been analysing the concept of brain drain and due to this the research branch has started expanding, and the phenomenon is being studied in a wide range of fields.

According to the Fragile States Index[11] , In the brain drain, India's ranking in world fragility Index continued worsening [12] after the Modi government came to power with a lower Human Flight and Brain Drain Index and an overall fragility rank of 114th. However, the index remains concerning when compared to other countries in the region.

Is Migration A Response To Air Pollution

When the AQI attains urgent situation levels, those who can do so should stay indoors and, if they can afford it, buy air purifiers for their homes[13] . Revenue is falling for businesses and restaurants. Households with adequate resources can escape to Himalayan hill retreats or the Goa coasts, a luxury which most people do not have. Some Delhi NCR malls have heavily invested on the poor conditions by installing air purifiers and luring crowds for clean air rather than shopping.

According to the International Organisation for Migration (IOM), it is a type of human mobility in which people have more authority and make decisions and choices about where they want to go. The IOM also predicts that the number of people migrating will grow as a result of the negative effects of climate change and destruction of the environment on their livelihoods, daily lives, and health [14].

The concept that environmental degradation has an influence on migration is not new. Many academics, including the Intergovernmental Panel on Climate Change (IPCC), have argued that climate change is likely to result in mass population migration as a result of extreme weather conditions as well as gradual environmental issues.

Air pollution can have three main features on a person's migration decision: physical health, mental health, and job satisfaction. People would not want to live in a city that causes them to be physically or mentally ill, nor would they want to reside in a city where they do not want to work due to toxic levels of air pollution. Apart from having a negative impact on physical health, air pollution has an important negative impact on mental health, causing a reduction in the quality of life. This may start encouraging adults to leave places where they feel mentally ill.

Who Moved, And What Are The Implication

The estimate of net migration outflows using census figures [15] , so we realised the individual characteristics of the people who migrated. For example, we observed that degree holders were twice as likely as junior high school graduates to migrate. Women were twice as likely as men to migrate, and prior to adulthood were also more likely to shift. In a nutshell, these inflows are driven mainly by well-educated individuals at the beginning of their professional careers. These patterns, combined with the peak value of the effect, reveal that air pollution has already adversely affected the demographic characteristics of India's regions.

When addressing economic growth, the environment is commonly considered as a contributing issue. It is still broadly accepted that the problem of pollution will be dealt with by future generations. The findings show that presently, the costs of pollution surpass [16] the significant economic benefits of residing in some large cities. Pollution has both environmental and economic consequences, and it is driving natural ability out of major cities. We hope that this serves as a wake-up call to the fact that pollution is shaping the demography and economy of our cities, and that the environmental consequences of growth must be regarded in our policy.

India has nine of the top ten cities in the world with the highest annual Fine particulate matter (IQAir, 2021), with over one million deaths each year contributing to PM2.5 ,High PM2.5 levels contribute to poor air quality, which is exacerbated by Diwali fireworks [17] . In 2017, it is estimated that air pollution killed 1.24 million people in India, with Delhi having one of the highest levels of particulate matter air pollution in the country.

The geography of Delhi differs, with major features for example the River Yamuna, the Godavari range, and the plains in between made of alluvial deposits of the latest structure [18] . The Delhi Mountain range and its four sections, northern, central, south central, and southern, cover the much more northern and eastern extension of the Aravalli hills, to spurs meeting the Yamuna at two points in the north and east.

The Ridge helps as an ecological barrier between the Thar Desert and the plains, trying to slow the movement of dust and wind from the valley. Moreover, the city's two main geographical features are the Yamuna River and the port part of the Godavari hill range. The Godavari hill range is densely forested.

As from the gathered national standard data from 62 jurisdictions worldwide [19] , which include 58 countries. Of the world's 136.06 million sq.km land under national jurisdictions, 71.70 million km2 (52.7%) lack a formal PM2.5 air quality standard, and 3.17 billion people live in areas without a level of quality. The existing regulations ranged from 8 to 75 g/m3, all of which were above the World Health Organisation's annual limit of 10 g/m3. The lowest PM2.5 standards were regularly exceeded, while the tougher standards were more often met. Several of the most populous jurisdictions proved compliance with fairly strict standards.

To facilitate accurate assessment of the hazards associated with PM2.5 exposure, the indicators used in PM2.5 standards for ambient air quality should be blended globally. Stringent PM2.5 requirements are not based solely on population density. Standardisation can also include brief standards to disclose PM2.5 peaks and troughs in high-pollution areas.

Air Quality And Environmental Injustice In India

Scientists and supervisors have multiple times described the situation as a public health crisis and it has evolved into one of the country's most heinous cases of environmental injustice, aggravated by the frequent pseudo-actions and hyperbole swirling around it.

Annually, the Judicial Branch steps up to cover for a lack of political will. People protest passively and, when action is taken, its incapability. The governments of Delhi, Punjab, and Haryana are attempting to play musical chairs with blame [20] . Almost everyone knows at the end of winter that the air will continue to suck the city's residents the following winter. But, while our soul is quick to bat an eye, how much responsibility do we, the urban elite, bear?

It is clearly well known that the situation is beyond control, that it has evolved into a disaster that lurks in the shadows during the summer, beckoning us into a false sense of safety, and then emerges as a full-fledged crisis in the winter.

The Indian Supreme Court has commonly stated the state to give a response, often in a specific direction - but is such intervention beneficial? Climate policy may not be within the court's domain of expertise, and the jury should not be making policies. However, the absence of action in that respect necessitates court intervention. The Indian Constitution is one of the few sovereign documents in the world with natural physical provisions.

The directive principles of state policy are not legally binding, but they must guide state policy. And a forthright judicial system will ensure that the state abides by them. It is challenging to describe environmental justice. It first emerged as a concept in the USA in the early 1980s. It is described by the US Environmental Protection Agency as "the equitable treatment and meaningful participation of all people, regardless of race, colour, national origin, or income, in the growth, implementation, and implementation of environmental laws, regulations, and policies" [21]. However, as the number of stakeholders grows, it becomes more difficult to define fair treatment for and by whom.

Even so, accessing the web of environmental justice is difficult. The Supreme Court recently ordered the Centre , as well as the governments of Punjab, Haryana, Uttar Pradesh, and Delhi, to address stubble burning, a big source of air pollution in Delhi [ 22] . When the authorities argued that farmers react to crop-burning because the glass between the rabi and kharif seasons is so limited, the bench responded that it had no sympathy for farmers because "they are doing it with complete knowledge," and that the situation is so severe that farmers must face strict action.

However, the problem is more complicated. Before governments can put a stop to crop-burning, systemic issues such as economic distress and labour shortages must be addressed. The court's orders do not provide long-term solutions, but rather force government officials to take immediate action.

Laws And Constitutional Provisions Related To Environment

Constitutional Provisions:
Preamble:
The Preamble of the Indian Constitution provides that our nation is based on a social structure, in which the state prioritises societal issues before personal matters. Its objective is to ensure that everyone enjoys a decent level of living, which is only feasible in an environment that is free from pollution. Given that pollution is a social issue, the State is obliged under the Supreme Law to focus more on this issue.

Fundamental Rights:
Ten essential responsibilities are contained in Part 4A, which was added to the Constitution by the 42nd Amendment of 1976. One of these ten duties, Article 51A(g), is related to the environment. Every citizen has a fundamental obligation to protect and enhance the natural environment, as per Article 51A(g).

Directive Principles of State Policy:
These guidelines, which are included in Part 4 of the Constitution, explain the chosen value that the state is required to follow. The Directive principles are addressed in Articles 36 to 51, and particularly, Articles 47 [23] and 48A concern protecting the environment.

Fundamental Rights:
The Constitution's chapter 3 concerns fundamental rights. Articles 14 to 32 cover fundamental rights; of these, Articles 14, 19, and 21 relate to the environment.

Writ Jurisdiction:
Articles 32 and 226 give the Supreme Court and High Court the power to issue writs. The writ jurisdiction of S.C. and H.C. differ in that we can move to S.C. only to enforce fundamental human rights, although in H.C. we can move for both fundamental rights and other purposes. As writ jurisdiction is used to settle the majority of environment issues, these rules are essential to the advancement of Indian environmental law.

Acts Made by legislature:
The National Green Tribunal Act, 2010
Any violation of these laws, or any order or decision made by the government in full compliance with these laws, may be countered before the NGT. Importantly, the NGT has not been given the authority to hear cases relating to the Wildlife (Protection) Act, 1972, the Indian Forest Act, 1927, and various state laws relating to forests, tree preservation, and so on [24].

As a result, specific and significant issues pertaining to these laws cannot be raised before the NGT. You must file a Writ Petition (PIL) with the State High Court or the Supreme Court, or file an Original Suit with an appropriate Civil Judge in the mandal where the project is located.

A fee of Rs. 1000/- is required for every application / appeal in which there is no claim for remuneration. In the occurrence that compensation is sought, the fee will be one percent of the amount sought, with a minimum of Rs. 1000/-.

Compensation claims can be made for:

• Compensation for accidents involving hazardous substances; Property restitution;
• Environmental restitution for areas determined by the NGT

The Air (Prevention and Control of Pollution) Act, 1981
The Air (Prevention and Control of Pollution) Act of 1981 (the "Air Act") is an act which provides for the prevention, control, and eradication of air pollution, and the formation of Boards at the Central and State levels to carry out such purposes.

The Air Pollution Act(1981) established ambient air quality standards to tackle the issues associated with air pollution. The Air Act aims to reduce air pollution by prohibiting the use of polluting fuels and toxins and regulating air smog appliances. The Air Act enables the State Government to declare any area or areas within the State as an air pollution control area or areas after consulting with the SPCB [25]

According to the Act, they require SPCBs' permission before creating or operating any industrial plant in the pollution prevention area. SPCBs will also be used to test the air in air pollution control areas, in addition to inspect pollution control equipment and manufacturing processes.

The Environment Protection Act, 1986 [26]
The Environment Protection Act,1986 Act empowers the government to take measures to protect and improve the environment's quality of life by establishing standards for emissions and discharges of pollution into the ambience by any person carrying on an industry or activity; regulating this same location of industries; managing hazardous wastes; and protecting public health and welfare.

The Central Government may issue notifications under the Environment Act for the protection of ecologically sensitive areas or guidance for matters under the Environmental Protection act from time to tim

In India, the central and state governments have taken a number of measures to reduce air pollution and improve air quality. A few initiatives, such as the use of liquefied natural gas (CNG) as a renewable fuels, the odd-even measures implemented in Delhi, the execution of Bharat Stage VI vehicle and fuel standards, the Pradhan Mantra Ujjwala Yojana (PMUY), and the National Clean Air Research program (NCAP), are examples of this initiative[27] .

With the cooperation of the respective state pollution control boards, the Central pollution control board ensures the monitoring and regulation of National ambient air quality in cities, towns, and industrial areas (SPCBs). Various industry measures have been implemented in India's urban cities under these plans.

A fusion of effective policies, techniques, and framework defines could aid in the development of an energy control strategy. Stiffer discharge limits, cleaner fuels, engine progressions, the creation of cleaner and greener vehicles, and post-emission treatment technologies could greatly decrease urban pollution levels. Concrete policy measures that limit people's exposure to air pollutants could be implemented.

Migrating industries to the outskirts of cities is a good example to consider .Limiting pollution from burning fuel could help to reduce pollution. From 2001 to 2006, the use of CNG-powered vehicles in Delhi reduced PM, CO, NOX, and SO2 emissions significantly.

Suggestions And Discussion
Air Pollution will lead to Mass Migration if it continues to grow at a bigger speed which will impact on our climate change. As air pollution does not respect boundaries of nations, it will lead to environmental degradation due to which many migrations will take place in the upcoming future.

As various action can be take place to combat air pollution such as:

• Conserve energy everywhere whether at home, work or anywhere.
• For effective vapour recovery, follow the directions for refuelling with gasoline. Be cautious not to spill any fuel, and make sure the gas cap is properly tightened.
• Think about switching to gas logs from wood.
• When it's cooler in the evening, fill up your automobile.
• Set air conditioners to no lower than 78 degrees to save energy.
• Put off or wait until later in the day any lawn and gardening tasks that require gasoline-powered equipment.

This paper enriches the literature in the following three ways: First, the above study utilised high-accuracy PM2.5 satellite raster data and India data to precisely identify the effects of air pollution on migrants' settlement intentions at the micro level. The study's robust findings provide new evidence for migrants' residential choices. Second, in order to reduce the adverse effects of intrinsic problems on the results of this paper, this study introduces the air flow ratio as a tool variable of PM2.5 in addition to controlling city characteristics and fixed effects.

Third, this paper theoretically reveals and provides appropriate data for the micro-mechanism whereby air quality may affect high-quality economic development via channels such as human capital accumulation. Despite the fact that all features normalise to high predictive power, the way different urban form indicators react to the dependent variable varies. Shape metrics, particularly CONTIG, have the biggest effect on PM2.5 trends in cities belonging to the high-high cluster, Eastern, and large urban enclaves.

All of these areas have a successful economy and a higher population density. Accumulation metrics[28] play a dominant negative role in PM2.5 level changes in decently developed cities, such as the Central region, as well as smaller and mid-sized cities. In contrast, the indicators describing the size and number of urban patches are the strongest predictors in the least developed cities belonging to the Indian region.

Conclusion
As per the results of the study, urbanisation in Increasing emphasis environmental pressure and, to some extent, contradicts air quality improvement. However, the recent decline in emissions caused by RU migration shows that by updating urbanisation and air pollution control laws, it is important to limit or even eliminate the future contradiction between urbanisation and air quality improvement.

Because of the urbanisation effect of cities, the urban per capita carbon footprint in developed countries that have already attained the mature stage, such as Austria, is lower than the rural predecessor. In this case, RU migration and a societal development of the urban population will cut emissions and benefit the environment.

The peak in pollutant emissions prompted by RU migration indicates that, whereas urbanisation currently contradicts air quality improvement in China, revised policies can make urbanisation and air quality targets accurate in the future. Actions should be taken to minimise urban per capita emissions by fully utilising agglomeration benefits.

End-of-pipe control innovation updates, along with energy system emission reductions, should be favoured for further reductions in emission intensity. Moreover, the production structure should be transformed by increasing the proportion of producer solutions and decreasing reliance on raw materials.

Award Winning Article Is Written By: Ms.Ishika Agarwal - Law College Dehradun, Uttaranchal University

Authentication No: MR408184886386-21-0324