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Air pollution occurs through so many aspect that is burning of petrol, or biology organism. It includes the air in or out not only human being but those very small insect which death by de gradation of lake biodiversity pollution change very badly also. Pollutants are responsible to our drinking water and even our homes. Environmental changes are being occured with our ecosystem that may cause harm or damage to living things. Environmental problems appear when it is an imbalance between human earning structures and natural processes. The environment is perturbed and segmented parepared for evolved. The population grows and its requirement for natural as well as man made resources. That could hunt the environment. It is important to be awake of through the environmental issues facing India and the world so that we can take fair scale steps to mitigate their effects.

Environmental Implications of Specific Population Factors

Population Size

No simple relationship exists between population size and environmental change. However, as global population continues to grow, limits on such global resources as arable land, potable water, forests, and fisheries have come into sharper focus. In the second half of the twentieth century, decreasing farmland contributed to growing concern of the limits to global food production. Assuming constant rates of production, per capita land requirements for food production will near the limits of arable land over the course of the twenty-first century. Likewise, continued population growth occurs in the context of an accelerating demand for water: Global water consumption rose six-fold between 1900 and 1995, more than double the rate of population growth.

Population Distribution

The ways in which populations are distributed across the globe also affect the environment. Continued high fertility in many developing regions, coupled with low fertility in more-developed regions, means that 80 percent of the global population now lives in less-developed nations. Furthermore, human migration is at an all-time high: the net flow of international migrants is approximately 2 million to 4 million per year and, in 1996, 125 million people lived outside their country of birth. Much of this migration follows a rural-to-urban pattern, and, as a result, the Earth's population is also increasingly urbanized. As recently as 1960, only one-third of the world's population lived in cities. By 1999, the percentage had increased to nearly half (47 percent). This trend is expected to continue well into the twenty-first century.

The distribution of people around the globe has three main implications for the environment. First, as less-developed regions cope with a growing share of population, pressures intensify on already dwindling resources within these areas. Second, migration shifts relative pressures exerted on local environments, easing the strain in some areas and increasing it in others. Finally, urbanization, particularly in less-developed regions, frequently outpaces the development of infrastructure and environmental regulations, often resulting in high levels of pollution.

Population Composition

Composition can also have an effect on the environment because different population subgroups behave differently. For example, the global population has both the largest cohort of young people (age 24 and under) and the largest proportion of elderly in history. Migration propensities vary by age. Young people are more likely than their older counterparts to migrate, primarily as they leave the parental home in search of new opportunities. As a result, given the relatively large younger generation, we might anticipate increasing levels of migration and urbanization, and therefore, intensified urban environmental concerns.

Other aspects of population composition are also important: Income is especially relevant to environmental conditions. Across countries, the relationship between economic development and environmental pressure resembles an inverted U-shaped curve; nations with economies in the middle-development range are most likely to exert powerful pressures on the natural environment, mostly in the form of intensified resource consumption and the production of wastes. By contrast, the least-developed nations, because of low levels of industrial activity, are likely to exert relatively lower levels of environmental pressure. At highly advanced development stages, environmental pressures may subside because of improved technologies and energy efficiency.

Within countries and across households, however, the relationship between income and environmental pressure is different. Environmental pressures can be greatest at the lowest and highest income levels. Poverty can contribute to unsustainable levels of resource use as a means of meeting short-term subsistence needs. Furthermore, higher levels of income tend to correlate with disproportionate consumption of energy and production of waste.

Global Climate Change

Recent years have been among the warmest on record. Research suggests that temperatures have been influenced by growing concentrations of greenhouse gases, which absorb solar radiation and warm the atmosphere. Research also suggests that many changes in atmospheric gas are human-induced. The demographic influence appears primarily in three areas. First, contributions related to industrial production and energy consumption lead to carbon dioxide emissions from fossil fuel use; second, land-use changes, such as deforestation, affect the exchange of carbon dioxide between the Earth and the atmosphere; and third, some agricultural processes, such as paddy-rice cultivation and livestock production, are responsible for greenhouse gas releases into the atmosphere, especially methane. According to one estimate, population growth will account for 35 percent of the global increase in CO₂ emissions between 1985 and 2100 and 48 percent of the increase in developing nations during that period. As such, both attention to demographic issues and the development of sustainable production and consumption processes are central responses to the processes involved in global warming.

Air Pollution

Undoubtedly one of the most pressing environmental issues in India is air pollution. According to the 2021 World Air Quality Report, India is home to 63 of the 100 most polluted cities, with New Delhi named the capital with the worst air quality in the world. The study also found that PM2.5 concentrations – tiny particles in the air that are 2.5 micrometres or smaller in length – in 48% of the country’s cities are more than 10 times higher than the 2021 WHO air quality guideline level.

Vehicular emissions, industrial waste, smoke from cooking, the construction sector, crop burning, and power generation are among the biggest sources of air pollution in India. The country’s dependence on coal, oil, and gas due to rampant electrification makes it the world’s third-largest polluter, contributing over 2.65 billion metric-tones of carbon to the atmosphere every year. 

The months-long lockdown imposed by the government in March 2020 to curb the spread of Covid-19 led to a halt in human activities. This unsurprisingly, significantly improved air quality across the country. When comparing the Air Quality Index (AQI) data for 2019 and 2020, the daily average AQI in March-April 2019 was 656, the number drastically dropped by more than half to 306 in the same months of 2020.  The months-long lockdown imposed by the government in March 2020 to curb the spread of Covid-19 led to a halt in human activities. This unsurprisingly, significantly improved air quality across the country. When comparing the Air Quality Index (AQI) data for 2019 and 2020, the daily average AQI in March-April 2019 was 656, the number drastically dropped by more than half to 306 in the same months of 2020. 

Unfortunately, things did not last long. In 2021, India was among the world’s most polluted countries, second only to Bangladesh. The annual average PM2.5 levels in India was about 58.1 µg/m³ in 2021, “ending a three-year trend of improving air quality” and a clear sign that the country has returned to pre-pandemic levels. Scientists have linked persistent exposure to PM2.5 to many long-term health issues including heart and lung disease, as well as 7 million premature deaths each year. In November 2021, air pollution reached such severe levels that they were forced to shut down several large power plants around Delhi. In recent years, the State Government of the Indian capital has taken some stringent measures to keep a check on air pollution. One of which is the Odd-Even Regulation – a traffic rationing measure under which only private vehicles with registration numbers ending with an odd digit will be allowed on roads on odd dates and those with an even digit on even dates. Starting from January 2023, there will also be a ban on the use of coal as fuel in industrial and domestic units in the National Capital Region (NRC). However, the ban will not apply to thermal power plants, incidentally the largest consumers of coal. Regardless of the measures taken to curb air pollution, as the World Air Quality Report clearly shows – the AQI in India continues to be on a dangerous trajectory.

Rank	Country	State	City	Avg. PM 2.5 Microgram/cubic meter
1	India	Rajasthan	Bhiwadi	106.2
2	India	UP	Ghaziabad	102
3	India	Delhi	Delhi	96.4
4	India	UP	Jaunpur	95.3
5	India	UP	Noida	91.4
6	India	UP	Bagpat	89.1
7	India	Haryana	Hisar	89.0
8	India	Haryana	Faridabad	88.9
9	India	UP	Greater Noida	87.5
10	India	Haryana	Rohtak	86.9

WHO’s Air Quality Guideline  5.0

Source=IQ Air’s world Air Quality Report 2021.

What Should Policymakers Do?

The policy implications of demographic influences on the environment are complicated and can sometimes be controversial. While some view large, rapidly growing populations in developing regions as the primary culprit in environmental decline, others focus on the costly environmental effects of overconsumption among the slowly increasing populations of the developed nations. These differing emphases naturally point to radically different solutions: slow population increase in less-developed nations or change destructive consumption and production patterns in the more-developed nations. This debate, however, presumes a one-step solution to the complex problems created by population pressures on the environment. Both population size and consumption influence environmental change and are among the many factors that need to be incorporated into realistic policy debate and prescriptions. Examples of policies that could address the environmental implications of demographic factors include policies to promote effective family planning, more effective rural development to slow migration to crowded urban centers, and incentives to encourage sustainable levels of consumption and the use of efficient, cleaner technologies

1. Central Statistical Organization, (2000), "Compendium of Environment Statistics", Ministry of Statistics and Programme Implementation, Government of India, New Delhi. 2. Central Statistical Organization, (2002), "Selected Socio-Economic Statistics", Ministry of Statistics and Programme Implementation, Government of India, New Delhi. 3. Office of the Registrar General India (207). “Selected Socio-Economic Statistics", Ministry of Statistics and Programme Implementation, Government of India, New Delhi. 4. Chopra R (2016). Environmental Degradation in India: Causes and Consequences. International Journal of Applied Environmental Sciences Vol.-11 (6), pp. 1593- 1601. 5. Registrar general Population Census of India, 2011. 6. Manish Kumar “Growing population and their environmental impacts in India”, IJMER Vol. 10, January 2021.