(i) A pure public good is one for which consumption is non-revival and from which it is impossible to exclude a consumer.
(ii) Pure public goods pose a free-rider problem. As a result, resources are depleted

(i) Environmental economics (EE) is the study of interactions between human economic activity and the natural environment.
(ii) EE is the subset of economics that is concerned with the efficient allocation of environmental resources

(i) Death of aquatic animals.
(ii) Disruption of food - chains.
(iii) Diseases.
(iv) Destruction of ecosystems.

Global warming is the current increase in temperature of the earth's surface (both land and water) and its atmosphere.

1. Use of noise barriers
2. Newer roadway for surface transport
3. Traffic control
4. Regulating times for heavy vehicles
5. Installations of noise barriers in the work place
6. Regulation of Loudspeakers

Environmental goods are typically non-market goods, including clear air, clean water, landscape, green transport infrastructure, public parks, rivers, mountains, forest and beaches.

(i) An ecosystem includes all living things (plants, animals and organisms) in a given area, interacting with each other and also with their non-living environments (weather, earth, sun, soil, climate, atmosphere).
(ii) It is the foundation of the Biosphere and determine the health of the earth.

(i) Environment means "all the conditions, circumstances, and influences surrounding and affecting the development of an organism or group of organisms".
(ii) It also means that the complex of physical, chemical and biotic factors that act upon an organism or an ecological community ultimately determine its form and survival.

(i) Land pollution is defined as, "the degradation of land because of the disposal of waste on the land".
(ii) Any substance that is discharged, emitted or deposited in the environment in such a way that it alters the environment causes land pollution.
Causes:
Deforestation and soil erosion:
(i) Deforestation carried out to create dry lands is one concern.
(ii) Land that is once converted into a dry land can never be made fertile again.
Agricultural activities:
(i) With growing human and pet animal population demand for food has increased.
(ii) Farmers use highly toxic fertilizers and pesticides which contaminates and poisons the land.
Mining activities:
(i) During extraction and mining, several land spaces are created beneath the surface.
Landfills:
(i) Garbage like plastic, paper, cloth, wood and hospital waste get accumulated.
(ii) Things that cannot be recycled become a part of the landfills that cause land pollution.
Industrialization:
(i) Due to increasing consumerism more industries are developed which lead to deforestation.
Construction activities:
(i) Due to urbanisation, large amount of construction activities are taking place.
(ii) Waste articles like wood, metal, bricks, are dumped at the outskirts of urban areas that lead to land pollution.
Nuclear waste:
(i) The leftover radioactive materials, harmful and toxic chemicals affect human health.
(ii) They are dumped beneath the earth to avoid any casualty.

Indoor Air Pollution:
(i) It refers to toxic contaminants that we encounter in our daily lives in our homes, schools and workplaces.
(ii) (e.g.) cooking and heating with solid fuels on open fires.
Outdoor Air Pollution:
(i) It refers to ambient air.
(ii) The common sources of outdoor air pollution are caused by combustion processes from motor vehicles, solid fuel burning and industry.

(i) The law of conservation of matter and energy, emphasizes that in any production system "what goes in must come out".
(ii) All resources extracted from the environment eventually become unwanted wastes and pollutants.
(iii) Production of output by firms from inputs results in discharge of solid, liquid and gaseous wastes.
(iv) Waste results from consumption activities by households.
(v) Thus material and energy drawn from environment are used for production and consumption and returned back to the environment as wastes.
(vi) \(\mathrm{R}=\mathrm{W}_{1}+\mathrm{W}_{2}\)
(vii) Input = Output

Introduction:
(i) Sustainable development is concerned with the welfare of the present and future generation.
(ii) It aims at satisfying the luxury wants of the rich and the basic necessities of the poor.
Definition:
(i) Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.
Goals:
(i) It is crucial to harmonize three core elements such as economic growth, social inclusion and environmental protection.
(ii) A set of 17 goals for the world's future can be achieved before 2030 with three unanimous principles fixed by United Nations such as Universality, Integration and Transformation.
1) End poverty in all its forms everywhere.
2) End hunger, achieve food security and improved nutrition and promote sustainable agriculture.
3) Ensure healthy lives and promote wellbeing for all at all ages.
4) Ensure inclusive and quality education for all and promote lifelong learning.
5) Achieve gender equality and empower women and girls.
6) Ensure access to water and sanitation for all.
7) Ensure access to affordable, reliable, sustainable and modern energy for all.
8) Promote inclusive and sustainable economic growth, employment and decent work for all.
9) Build resilient infrastructure, promote, sustainable industrialization and foster innovation.
10) Reduce inequality within and among countries.
11) Make cities inclusive, safe, resilient and sustainable.
12) Ensure sustainable consumption and production pattern.
13) Take urgent action to combat climate change and its impacts
14) Conserve and sustainably use the oceans, seas and marine resources.
15) Sustainably manage forests, combat desertification, stop and reverse land degradation, stop biodiversity loss.
16) Promote just, peaceful and inclusive societies.
17) Revitalize the global partnership for sustainable development.

Introduction:
1. Externality refers to external effects or spillover effects resulting from production or consumption on the third parties.
Definition:
1. It may be defined as "the cost or benefit imposed by the consumption and production activities of the individuals on the rest of the society not directly involved in these activity and towards which no payment is made".
Types:
1. Beneficial externalities are called "positive externalities".
2. Adverse externalities are called "negative externalities".
Positive Consumption Externality
1. When some residents of a locality hire a private security agency to patrol their area, the other residents of the area also benefit from better security without bearing cost.
Negative Consumption Externality
1. A person smoking cigarette gets satisfaction but this act causes dissatisfaction to the non-smokers who are driven to passive smoking.
Positive Production Externality
1. The ideal location for beehives is orchards.
2. While bees make honey, they also help in the pollination of apple blossoms.
3. The benefits. accrue to both producers (honey and apple).
4. This is called reciprocal untraded interdependency.
Negative Production Externality
1. They include pollution generated by a factory that imposes costs on others.
2. The emissions and effluents of a factory cause air and water pollution.
3. Water becomes contaminated and unfit for drinking (e.g.) Tanneries.
4. The innocent community bears the external cost for which it is not compensated.