Chemistry - Environmental Hazards

Any agent that can cause harm or damage to humans, property, or the environment.

The probability of suffering harm (injury, disease, death, or damage) from exposure to a hazard.

The use of statistical methods to estimate the potential harm a hazard may cause to humans or the environment.

The process of deciding how to reduce a risk and determining acceptable levels and associated costs.

Biological, chemical, nuclear, natural, cultural, and lifestyle hazards.

Events like fires, earthquakes, volcanic eruptions, floods, and storms.

Hazards arising from human activities such as unsafe working conditions, crime, and poverty.

Risks caused by personal choices such as smoking, poor diet, and excessive alcohol consumption.

Threats caused by organisms or biological agents such as bacteria, viruses, and parasites.

A disease caused by pathogens (bacteria, viruses, parasites) that invade and multiply in the body.

Flu, malaria, tuberculosis, and measles.

Bacterial diseases spread through the multiplication of bacteria, while viral diseases spread by hijacking host cells to replicate.

An infectious disease that can spread from one person to another.

A disease that does not spread between people and is caused by internal or environmental factors.

Cardiovascular diseases, cancer, asthma, diabetes, and malnutrition.

A large-scale outbreak of an infectious disease within a region or country.

A global epidemic affecting multiple countries or continents.

Factors like antibiotic resistance and increased immunity of disease vectors (e.g., mosquitoes to pesticides).

Air, water, food, body fluids, and droplets from coughing or sneezing.

It makes bacteria harder to treat, which increases the spread and severity of diseases.

Due to limited healthcare access, sanitation issues, and higher exposure to pathogens.

It enables preventive measures like sanitation, vaccination, and controlling exposure pathways.

A toxic chemical is a substance that can cause temporary or permanent harm or death to humans and animals.

Arsenic, lead, mercury, vinyl chloride, and polychlorinated biphenyls (PCBs).

Carcinogens, mutagens, and teratogens.

Carcinogens are substances (chemicals, radiation, or viruses) that can cause or promote cancer.

Cancer is a disease where malignant cells multiply uncontrollably, forming tumors that damage the body.

Arsenic, benzene, formaldehyde, UV radiation, PCBs, radon, and tobacco smoke chemicals.

Because there is often a long latency period (10–40 years) between exposure and symptoms.

Mutagens are chemicals or radiation that cause changes (mutations) in DNA.

DNA mutations caused by mutagens can result in cancer or genetic disorders.

Nitrous acid formed from food preservatives can cause mutations linked to stomach cancer.

Teratogens are substances that cause harm or birth defects in embryos or fetuses.

Alcohol, benzene, cadmium, lead, mercury, PCBs, and thalidomide.

Alcohol consumption during pregnancy can cause low birth weight and developmental, behavioral, and mental problems in offspring.

Carcinogens cause cancer, mutagens alter DNA, and teratogens cause birth defects in developing embryos.

Nuclear hazards arise from exposure to radioactive substances and ionizing radiation.

It is the process by which unstable atoms transform into stable ones, releasing energy and radiation.

Gamma rays, beta particles, and alpha particles.

Gamma rays have the highest penetration power among common radioactive emissions.

Cosmic rays, radon gas, soil, rocks, air, water, and food containing radioactive substances.

Nuclear power plants, nuclear accidents, X-rays, medical diagnostics, and laboratory equipment.

Effects on body cells that can cause diseases like cancer and reduce lifespan.

Damage to genes that can be passed to future generations as inherited disorders.

Because genetic damage affects future generations, not just the exposed individual.

Radiation damages DNA and disrupts cell regulation, leading to uncontrolled cell growth.

Because radiation effects can persist across generations and ecosystems.

UV-C radiation splits oxygen molecules (O₂) into free oxygen atoms, which then combine with O₂ to form ozone (O₃).

Ozone absorbs UV-B and UV-C radiation and breaks down into oxygen molecules, continuing a natural cycle.

A closed-loop cycle where ozone is continuously formed and destroyed.

CFCs are human-made compounds used in refrigeration, aerosols, and foams that release chlorine in the stratosphere.

They release chlorine atoms under UV radiation, which catalytically destroy ozone molecules.

They do not easily degrade, dissolve, or react, allowing them to remain long enough to reach the stratosphere.

Chlorine breaks ozone into O₂ and forms ClO; then oxygen reacts with ClO to regenerate chlorine, allowing repeated ozone destruction.

The ozone hole is a region of significantly reduced ozone concentration, especially over Antarctica.

It is not an actual hole but an area where ozone is highly diluted.

From August through November each year.

Increased UV-B radiation reaching Earth’s surface.

Skin cancer, sunburn, eye damage, cataracts, immune suppression, and premature aging.

It reduces phytoplankton populations, disrupting marine food chains and biodiversity.

It reduces crop yields for plants like corn, rice, soybean, and wheat.

Damage to materials like plastics and paints, leading to financial losses.

The greenhouse effect is the warming of Earth caused by atmospheric gases trapping infrared radiation.

Like glass traps heat in a greenhouse, gases trap heat in Earth’s atmosphere.

Earth’s warming is due to gases absorbing and re-radiating infrared radiation, not glass trapping heat.

Gases that absorb and re-emit infrared radiation, warming the Earth’s surface.

They do not absorb infrared radiation effectively.

Water vapor absorbs more infrared radiation than any other greenhouse gas.

Carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), ozone (O₃), and water vapor.

It measures how much heat a greenhouse gas traps over a specific time compared to CO₂.

Methane has a higher GWP than carbon dioxide over 100 years.

Fossil fuel burning, agriculture, deforestation, landfills, and industrial activities.

Global warming is the increase in Earth’s average temperature due to enhanced greenhouse effect.

Rising temperatures, melting ice caps, sea-level rise, habitat loss, and extreme weather events.

It disrupts ecosystems, causing species migration and extinction.

It alters water supply patterns, causing droughts and floods.

Trees absorb CO₂, so their removal increases atmospheric carbon dioxide levels.

Natural effect maintains Earth’s temperature; human-enhanced effect increases warming due to excess greenhouse gases.

It slows global warming and reduces climate-related environmental hazards.