Environmental Science: Human Population, Health Hazards, and Air Pollution

A set of vocabulary practice flashcards defining key concepts from Module 2 (Human Population), Module 15 (Health Hazards), and Module 12 (Air Pollution).

Exponential growth

The growth of any quantity at a fixed percentage per unit of time that starts slowly and then increases dramatically, graphed as a J-curve.

Carrying capacity

The maximum population of a given species that a particular environment can sustain indefinitely without degradation.

Population crash

A rapid decline in population size that occurs when a population exceeds the carrying capacity of its environment.

Total fertility rate (TFR)

The average number of children born to women of childbearing age in a population.

Life expectancy

The average number of years a person in a given population is expected to live.

Infant mortality rate

The number of babies out of every $1000$ born that die within their first year of life.

Age structure

The percentage or distribution of a population among pre-reproductive ($0-14$), reproductive ($15-44$), and post-reproductive ($45\text{ and older}$) age groups.

The tragedy of the commons

A phenomenon that occurs when the number of resource users and their rate of resource use outpaces the replenishment rate, leading to resource depletion.

Ecological tipping points

Critical thresholds reached when environmental degradation causes an irreversible change in an ecosystem.

IPAT model

A model comparing environmental impact calculated as $\text{Impact (I)} = \text{Population (P)} \times \text{Affluence (A)} \times \text{Technology (T)}$.

Demographic transition

A four-phase process whereby a country's population growth rate declines as it industrializes and develops economically.

Poverty

A condition in which people are unable to meet their basic needs for adequate food, water, shelter, health care, and education.

Environmental refugees

Individuals forced to leave their homes or communities because of severe environmental degradation, drought, or climate change.

Biological hazards

Health hazards originating from pathogens such as bacteria, viruses, and parasites that cause disease.

Chemical hazards

Health threats that originate from harmful chemicals present in the air, water, soil, food, and manufactured products.

Cultural hazards

Health hazards arising from societal conditions, including poverty, unsafe working conditions, conflict, and criminal assault.

Lifestyle health hazards

Health risks resulting from personal habits and choices, such as smoking tobacco, poor diet, and drug use.

Infectious disease

An illness caused by the invasion and reproduction of a pathogen within host tissues.

Transmissible disease

An infectious disease that can be transmitted from person to person through air, water, food, body fluids, or vectors.

Epidemic

A large-scale outbreak of an infectious disease in an area or country.

Pandemic

A global epidemic of an infectious disease that spreads across multiple countries or worldwide.

Carcinogens

Chemicals, types of radiation, or viruses that cause or promote the development of cancer.

Mutagens

Chemical agents or radiation that increase the frequency of mutations in the DNA of living cells.

Teratogens

Chemicals or agents that cause harm, birth defects, or malformations to a developing fetus or embryo.

Neurotoxins

Harmful substances, such as mercury, lead, and arsenic, that damage the nervous system, brain, and spinal cord.

Toxicity

A measure of the degree to which a substance is harmful to an organism.

Biological magnification

The process by which the concentrations of chemical toxins increase in tissues as they move upward through successive trophic levels in a food web.

Acute effect

An immediate or rapid harmful physical reaction to chemical or hazard exposure, ranging from dizziness to death.

Chronic effect

A permanent or long-lasting consequence caused by exposure to a single or repeated dose of a substance.

Risk assessment

The scientific process of estimating how much harm a hazard can cause to human health or the environment.

Risk management

The administrative and policy process of determining whether and how to avoid risks and at what cost.

Hormonally active agents (HAAs)

Molecules that mimic or block natural hormones, disrupting endocrine signaling and altering sexual development.

Precautionary principle

A strategy asserting that when preliminary evidence shows an activity or chemical could harm health or the environment, precautionary steps must be taken to prevent harm.

Troposphere

The lowest layer of the atmosphere, containing $78\%$ nitrogen, $21\%$ oxygen, and greenhouse gases essential for regulating Earth's temperature.

Stratosphere

The second layer of Earth's atmosphere, situated above the troposphere and containing the protective ozone layer.

Natural greenhouse effect

The warming of the lower atmosphere resulting from heat absorption and reradiation by greenhouse gases like water vapor, $CO_2$, $CH_4$, and $N_2O$.

Primary air pollutants

Chemicals emitted directly into the air by natural processes or human activities that build to harmful levels.

Secondary air pollutants

Harmful compounds created in the atmosphere when primary air pollutants react with one another or with atmospheric components.

Suspended particulate matter (SPM)

Solid particles and liquid droplets that remain suspended in the atmosphere, originating from industrial plants, vehicles, and dust.

Volatile organic compounds (VOCs)

Organic compounds that exist as gases in the atmosphere or evaporate readily, such as methane ($CH_4$) and benzene.

Industrial smog

A mix of sulfur dioxide ($SO_2$), suspended sulfuric acid droplets ($H_2SO_4$), and soot produced mainly by burning coal.

Photochemical smog

A mix of secondary pollutants, including tropospheric ozone ($O_3$), formed when volatile organic compounds and nitrogen oxides react under sunlight.

Acid deposition

The falling of acids and acid-forming compounds from the atmosphere to Earth's surface via wet deposition (rain, snow, fog) or dry deposition (particles).

Montreal Protocol

An international treaty signed in 1987 designed to protect the stratospheric ozone layer by phasing out the production of chlorofluorocarbons (CFCs).

Stockholm Convention

An international environmental treaty signed by 168 countries to regulate and phase out 21 persistent organic pollutants (POPs).