I. ENVIRONMENTAL POLLUTION

Environment problem is a very big issue and problem for the human society. More than 7 million people die each year from air pollution, according to a new study. It is far more than the estimated 2.6 million people who have died from Covid-19 since it was detected more than a year ago.

Pollution is the world's largest environmental threat to health, responsible in 2020 for an estimated 10 million premature deaths, or $15\mathrm{\%}$ of all deaths globally, and 275 million Disability-Adjusted Life Years. This is equal to 0.035 year life expectancy lost on global basis.

Annual deaths due to environmental pollution world over are shown in the following table (Table 1.1). More than three fourths deaths occur due to air pollution. One fifth of the deaths occur due to water pollution. About 4% deaths occur due to land pollution. For better visualization, this is also shown in figure (Fig 1.1).

As can be seen from the table, 76.17% of the deaths occur due to air pollution followed by water pollution. Long-term health effects from air pollution include heart disease, lung cancer, and respiratory diseases such as emphysema. Air pollution can also cause long-term damage to people's nerves, brain, kidneys, liver, and other organs. Some scientists suspect air pollutants cause birth defects.

Water pollution causes typhoid, cholera, hepatitis and various other diseases and destruction of Ecosystems: Ecosystems are extremely dynamic and respond to even small changes in the environment. Water pollution can cause an entire ecosystem to collapse if left unchecked.

Within the pollution sector, air pollution is the most damaging one. Worldwide it causes 76.17% of all the pollution deaths. The Premature deaths attributable to the components of air pollution are shown in Table 2. See also Fig. 1.2.

Trend of air pollution in the world is shown in figure 1.3. It is good to see that world deaths are consistently decreasing. The decreasing rate is 1.87 per 100,000 people per year.

According to World Health Organization, Air Pollution causes 7 million premature deaths a year ${}^{(02)}$. The World Health Organization (WHO) said air pollution was now one of the biggest environmental threats to human life, leading to seven million premature deaths a year.

a) Life Expectancy

Life expectancy is a statistical measure of the average time the human are expected to live, based on the year of its birth, its current age, and other demographic factors including sex. The most commonly used measure is life expectancy at birth (LEB).

The factors that help increase human life expectancy are better health care and hygiene, healthier life styles, sufficient food and improved medical care and reduced child mortality mean that people can expect to live much longer than our ancestors just a few generations ago.

Despite some odds, especially in the pollution sector, world death rate is declining. As a result, world life expectancy is increasing. This is depicted in Table 2.1 and Figure 2.1.

Another odd is increase in the life year losses due to non - communicable diseases (NCD). This is evident from figure 2.2.

The average Life expectancy data of world population for several years is plotted and presented in Fig 2.3. The trend line is also shown. The statistical model with parameters is shown.

Statistical model is

Life Expectancy (years) = 0.3205 * years - 573.23

$R^2=0.9671$; time period 960 - 2016.

However the average life expectancy is consistently increasing. Every year, 0.3205 year is increasing in the world population life expectancy on average. This means every three years, one year life expectancy is increasing on the average life expectancy of the world population meaning 4 months in every year. See Fig. 2.3

Since the world countries are much heterogeneous in characters, there are also variations in the life expectancies between different countries, regions and level of economic development. In the table and figure here the variations in life expectancy based on the World Bank Income Groups are depicted. See the Table 2.4 and Fig. 2.4.

High income group has the highest life expectancy (81.84 years). Placed in order, the low income group has the lowest life expectancy (63.43 years). The trend of the life expectancies of the WB income groups is shown in figure 2.4.

II. EFFECT OF ENVIRONMENTAL POLLUTION ON LIFE EXPECTANCY

a) Life Expectancy Loss

Life year loss to the world is the most important effect pollution inflicts on the world people. In this connection, Disability Adjusted Life Years Lost in the world in 2020 in NCD is shown in the following table (Table 3.1).

Here it can be seen that the maximum loss (19.22%) occurs due to cardiovascular disease followed by cancer (12.27%). These two diseases burden together account for 31.49% of all the diseases.

The life year losses on account of these diseases are shown in Table 3.1.

The total loss per year on account of CD is equivalent to 0.076 year life expectancy loss on the whole world. The life year loss due to CD is $30.77\mathrm{\%}$ of that of NCD.

b) Shortening of Life Expectancy

Environmental pollution has adverse effect on human life. It shortens the life expectancy. World picture of shortening of life expectancy by pollution is shown in Table 3.2.

Life expectancy is shortened maximum by air pollution (1.90 years) resulting a loss of life years of 9,880.00 million life years followed by heavy stress 7,599.20 life years. Overall, the picture of world life year losses (2020) is shown in figure 3.1.

The life expectancy shortening and losses of life years are shown graphically in figures 3.2 and 3.2, Fig. 3.2: Life Expectancy (years) Shortened

c) Potential Gains in Life Expectancy

It is noted that if the measures can be taken to stop the losses in full, the losses can be recovered in full and the life expectancy can be increased to the extent shown. But it is really difficult to achieve this. So, two scenarios are prepared for potential gains in the average expected life years.

Scenario A: Elimination of all deaths from specific diseases in people aged 30–70 years

Scenario B: Reduction in deaths from specific disease in people aged 30–70 years by a third.

Both the scenarios are shown in Table 3.3. The Sustainable Development Goal is set by the United Nations.

(The Lancet GlobalHealth) estimated in the Sustainable Development Goal two scenarios of potential gains.

The potential gains in life expectancy from the diseases according to World Bank Income Group are shown in Table 3.3.

The potential gains in average expected life years and other related information are shown in Table 3.4 ${}^{(04)}$.

Differences can better be visualized from the figure 3.4. Maximum and almost the same value of life expectancy are achieved in low income countries and lower middle income countries.

Regional Life Year Loss and Life Expectancy Loss are shown in Table 3.5 ${}^{(02)}$. The variations in life year loss and life expectancy loss may be marked region wise. The avoidable life expectancy loss is in East Asia 3.0 years.

LLE loss of life expectancy