APES Unit 6 - Air Pollution & Human Health

Stockholm Convention

- A 2001 agreement among 127 nations concerning 12 chemicals to be banned, phased out, or reduced (restricted global use of some chemicals) - 12 chemicals: the "dirty dozen" - DDT, PCBs, etc. (all were endocrine disruptors) - By 2017, 32 chemicals were listed

Secondary pollutants

- A primary pollutant that has undergone transformation in the presence of sunlight, water, oxygen, or other compounds - Transformed by sunlight or water - Conversion to secondary pollutants occurs more rapidly during the day and in wet environments Ozone (NOx, VOCs, and sunlight - precursors to ozone) The main components of acid deposition: sulfate and nitrate Control: Consider the primary sources that create them and factors that may lead to the formation, breakdown, or reduction in the secondary pollutants themselves

Clean Air Act

- Acid deposition reduced in US due to lower SO2 and NO emissions Acid Rain Program: led to reductions in sulfur emissions - Provision for the buying and selling of allowances that authorized the owner to release a certain quantity of sulfur - Each allowance authorizes a power plant/industrial source to emit one ton of SO2 during a given year - Sulfur allowances are awarded annually to existing sulfur emitters proportional to the amounts of sulfur they were emitting - Ex. a facility emitting 1,000 tons of SO2 most possess at least 1,000 allowances that are usable in that year - Sulfur allowances can be bought and sold on open market by anyone - Can also sell unused sulfur emission allowances

Explain why the ozone "hole" first appeared over Antarctica (discuss the circumpolar vortex and stratospheric clouds) and why ozone concentrations are lowest in spring in the S. Hemisphere.***

- Antarctic ozone depletion is seasonal - Each year, depletion occurs from late winter through early spring in Southern Hemisphere (hole largest in early spring) - Depletion caused an area of severely reduced ozone concentrations over most of Antarctica, creating the "ozone hole" - Depletion not as severe from Jan to April (doesn't cause hole) Cause of the ozone hole formation - Polar winter: Extremely cold weather conditions→ buildup of ice crystals mixed with nitrogen oxide (perfect surface for stable Cl2 formation and accumulation; atmospheric chlorine interacts with ice crystals) No ozone forms in the dark of winter→ thinning - Spring: Sun reappears, causing UV radiation to break down Cl2 into Cl, which in turn catalyzes the destruction of ozone Thinning diminishes bc temp rises and chlorine gets diluted **NOTE: Decreasing strat. ozone concentration is NOT related to temp. It is caused by breakdown reactions resulting from increase chlorine concentrations in atmosphere

Atmospheric temperature influences fog formation

- As temp increases, VOC emissions increase - As temp increases, NOx emissions from fuel combustion increases - Many chemical reactions that form ozone and other photochemical oxidants proceed more rapidly at higher temps - Smog concentrations increase when temperatures are higher

Video and article notes - Antarctica ozone hole

- Colder temperatures are one of the factors that activate ozone depletion - Weather patterns play a vital role in determining the ozone hole's extent each year - Colder conditions help form polar stratospheric clouds (PSCs)→cloud particles activate ozone layer destroying forms of chlorine and bromine compounds - Compounds stem from human production + aerosol sprays and refrigerants - Peaks during late winter, early spring (Low temps, sun's rays return) - Compounds have more than 50 year lifespan: why we're still seeing their effects on the environment today - Ozone hole over Antarctica is expected to gradually become less severe, as CFCs continue to decline and scientifically supported international action Polar vortex: a large area of low pressure + cold air surrounding both poles - It ALWAYS exists near the poles, but weakens in summer and strengthens in winter - The term "vortex" refers to the counter-clockwise flow of air that helps keep the colder air near the Poles

Describe anthropogenic ozone depletion and mitigation strategies

- Depletion greatest at the poles, but occurs worldwide - Antarctic ozone depletion is seasonal - New Zealand: erratic but gradually decreasing trend of ozone concentrations - Increased use of CFCs as refrigerants led to more rapid depletion - CFCs introduce chlorine (Cl) intro stratosphere - Montreal Protocol on Substances that Deplete the Ozone Layer

Random Facts - Risk Analysis

- EPA considers the limit of acceptable risk for environmental hazards as 1 in 1,000,000 - Motor vehicle accidents has the highest probability of death in the US

Carbon monoxide (CO)

- Indoor and outdoor air pollutant - Colorless, odorless gas - Occurs as a result of malfunctioning exhaust systems on furnace heating systems (most commonly natural gas heaters) - Malfunction: air escapes (ex. bc natural gas burns relatively cleanly with little odor, a malfunctioning natural gas burner can cause this CO to accumulate) - In the body, CO binds with hemoglobin more efficiently than O2→ interfere with O2 transport in blood (leads to O2 deprivation in brain→ death); use CO detectors

Asbestos

- Long, thin, fibrous silicate mineral with insulating properties; can cause cancer when inhaled - Used as an insulator on steam and hot water pipes and in shingles - Old/damaged insulators cause fibers to become airborne→ enter respiratory tract - No longer used as insulating material in US (only found in older buildings) - Removal of asbestos insulation must be done under tightly controlled conditions bc concentration of it in the air can be greater in the year after removal then during the year before removal - Respiratory diseases: respiratory ailments, asbestosis, and lung cancer - Manufactured form: asbestos is relatively stable and not dangerous until disturbed

Smog Reduction

- Main component of photochemical smog: ozone (secondary pollutant) - Control efforts must be directed toward reducing precursors (primary pollutants) Mostly been directed at reducing VOC emissions in urban areas - Less VOCs = fewer compounds to interact with NOx = more NOx available to recombine with ozone (good!) - Reduce amount of gasoline spilled at gas stations - Restrict evaporation of dry-cleaning fluids - Restrict use of lighter fluid (a VOC) for starting charcoal BBQs - Reduce use of wood-burning stoves or fireplaces - Reduce number of bakeries - Restricting automobile use - Driving every other day in Mexico City - Expanded public transportation networks, etc. in China

VOCs

- Many used in building materials, furniture, glues, paints (home products) - One of the most toxic of these compounds: formaldehyde - Particle board and carpeting glue - Common in new homes and produced made from pressed wood (i.e. bookcases - normal wood bookcases do not release though) - Pungent smell; volatile and emits gases over time - High enough concentrations in confined spaces cause burning sensation in eyes and throat, breathing difficulties, asthma - People develop a sensitivity to formaldehyde over time with continued exposure (increased irritation) - Shown to cause cancer in lab animals and suspected as human carcinogen - Detergents, dry-cleaning fluids, deodorizers, solvents may contain VOCs and can be harmful if inhaled - Plastics, fabrics, paints, construction materials, synthetic carpets may release VOCs over time→ decrease exposure by using wood flooring instead of carpeting OR natural fiber instead of synthetics

Technological solutions to reduce exposure to indoor air pollution

- More efficient cooking stoves (using a fan to facilitate greater O2 delivery) - BioLite HomeStove: small stove that reduces amount of firewood needed to cook, and lowering the amount of indoor air pollution emitted (ensures complete combustion) - Ventilation of cooking areas - Cooking outside - Change customs and practices that will reduce indoor air pollution exposure

Catalytic converters: Reduces NOx, CO, hydrocarbons emissions; increases CO2 emissions

- New automobiles sold in US required to include catalytic converter (NOx emissions from automobiles reduces) - Devices in the exhaust systems that convert harmful gases CO and NOx into less harmful products through redox reactions (using metal catalysts) - To operate properly: precious metals in the catalytic converter (mostly platinum and palladium) cannot be exposed to lead→ gasoline could no longer contain lead

Radon

- Radon-222 (radioactive gas that occurs naturally from uranium decay) that exists in granitic and other rocks + soils (primary sources of radon) in many parts of the world - Depending on the underlying bedrock and soils, the potential for radon exposure exists in houses in certain parts of the US (mostly in northern midwest) - Significant exposure: if radon seeps into home through cracks in the foundation or from underlying rocks, soil, groundwater - Radon-222 decays within 4 days to a radioactive daughter product, polonium-210 - Either radon or polonium can attach to dust and other air particles→ people inhale - Second leading cause of lung cancer, after smoking - EPA suggests people test homes for airborne radon and increase ventilation in homes and underground spaces below the house if high radon concentrations - Can also seal cracks in basement (if radon is coming from soil and bedrock)

Particulate Matter Removal: Gravitational settling

- Relies on gravity as exhaust travels through smokestack and particles settle to bottom; ash residue accumulated must be disposed in landfill - BUT depending on the fuel that was burned, the ash may contain high concentrations of metals that require special disposal

Persistent organic pollutants (POPS)

- Synthetic carbon-based molecules that break down very slowly in the environment - Chemicals that cause harmful effects on humans and organisms may become ever larger risks when they persist for many years - Many modern chemicals are designed to break down much more rapidly - Soluble in fat, so they accumulate in an organisms' fatty tissues

Other air pollution control strategies

- Use of fuels that contain fewer impurities; use of low-sulfur coal or oil (although more expensive) Fluidized bed combustion - Granulated coal is burned in close proximity to calcium carbonate - Heated calcium carbonate absorbs SO2 and produces calcium sulfate (can be used in sheetrock production) - Some of the SOx that does escape the combustion process can be captured by other methods after combustion - Uses bed of sand particles Reduce burn temperatures and control amount of oxygen - Procedure utilized in factories and power plants - Reduce NOx emissions (hotter temperatures and the presence of O2 increase NOx) - BUT this can result in less-complete combustion (reduces efficiency of process, increasing amount of PM and CO)

Particulate Matter Removal: **Scrubbers

- Uses a combo of water and air that separate and removes particles - Particles are removed in the scrubber in a liquid or sludge form and clean gas exits - Sludge is collected and processed for disposal - Particles sometimes ionized before entering scrubber to increase efficiency - Overall: particles are "scrubbed" from the exhaust steam by water droplets - Removes PM and SOx - Reduces pollution BEFORE entering atmosphere

Particulate Matter Removal: **Electrostatic precipitators

- Uses electrical charge to make PM coalesce (come together) so they can be removed - Polluted air enters precipitator and electrically charged particles within are attracted to negative or positive charges on the sides of the precipitator - The particles come together + clean gas exits precipitator - Reduces pollution BEFORE entering atmosphere

Buildup of photochemical smog

- VOCs come from human activity (i.e. spilling gasoline on pavement) and natural sources (i.e. forests) - When VOCs are absent or in small supply→ cycle of ozone formation and destruction takes place on daily basis and relatively small amounts of photochemical smog form (normal) Different scenario when VOCs are present in larger quantities: BUILDUP OF PHOTOCHEMICAL SMOG First part is same: NO2 → NO + O → O + O2 → O3 → photochemical smog - BUT bc VOCs have combined with NO in a strong bond, NO is no longer available to combine with ozone - VOCs combine with NO to form photochemical oxidants, reducing the amount of ozone that will break down later and contribute to prolonged periods of photochemical smog NO + VOCs → photochemical oxidants → photochemical smog - Explains daytime accumulation of ozone in urban areas with abundance of both VOCs and NO2 - Photochemical smog also occurs in rural areas with trees and shrubs that produce VOCs through forest fires

Sick building syndrome

A buildup of toxic pollutants in an airtight space (seen in newer buildings in developed countries in the temperate zone); mostly in office buildings - Is a result of off-gassing→ indoor levels of VOCs, hydrocarbons, etc. are high due to synthetic materials and glue - Headaches, nausea, throat or eye irritation, fatigue Indoor sources: Inadequate or faulty ventilation; chemical contamination from glues, carpets, furniture, cleaning agents, and copy machines - Products made with synthetic materials and glues that may not have fully dried out Outdoor sources: Vehicle exhaust transferred through building air intakes; molds and pollen (biological contamination)

Allergens

A chemical that causes allergic reactions - NOT pathogens, BUT are capable of causing an abnormally strong response from the immune system - Breathing difficulties and even death - Only causes allergic reactions in a small fraction of people - Found in chemicals naturally found in peanuts, milk, several drugs (penicillin and codeine)

Endocrine disruptors

A chemical that interferes with the normal functioning of hormones in an animal's body - Hormones normally manufactured in the endocrine system and released into the bloodstream in very low concentrations→ as hormones move through body, they bind to specific cells→ binding stimulates cell to respond in a way that regulates body functioning (Growth, metabolism, development of reproductive organs) Endocrine disruptors: bind to receptor cells and cause the cell to respond in ways that are not beneficial to the organism (they also mimic hormones) - Ex. group of reproductive hormones that can be found in wastewater: wastewater may contain hormones from animal-rearing facilities, human birth control pills, pesticides that mimic animal hormones - Scientists find that male fish, reptiles, amphibians are becoming feminized (i.e. testes that produce both egg and sperm OR have low sperm counts) - Interfere with production of testosterone (causes males to have higher concentrations of estrogen and lower testosterone) - Low sperm counts and increased risk of breast cancer in women **Sources: wastewater from animal-rearing facilities, DDT, municipal wastewater NOT acid deposition

Photochemical oxidants

A class of air pollutants formed as a result of sunlight (photo) acting on compounds such as nitrogen oxides and sulfur dioxide Remove electrons from other substances In the presence of NOx and SOx, photochemical oxidants ca enhance the formation of certain PM, contributing to scattering light→ smog→ photochemical and industrial smog Harmful to plant tissue, human respiratory tissue, construction materials Also economically harmful: poor visibility in vacation areas Ex. Ozone (O3)

Acid deposition

A deposition with a pH lower than 5.6 (rain that is unusually acidic) - Largely the result of human activity - Natural processes, like volcanoes, can contribute to its formation too - Forms as a result of nitrogen oxides and sulfur dioxide

Lyme Disease

A disease caused by a bacterium that is transmitted by ticks (vectors) - Primary vector: black-legged tick (deer tick) - After hatching from eggs, they spend their first stage of life attached to birds and small rodents. If infected, it can be transferred to the tick feeding on the host's blood. They then attach to larger mammals like deer and humans - First discovered in Lyme, Connecticut, BUT recently discovered in a frozen mummy - Most infections in northeastern US - Health effects: red bullseye at tick attachment site, flu like symptoms, arthritis, various neurological disorders - Cured using modern antibiotics

Infectious disease

A disease caused by a pathogen (infectious agents) - Ex. Pneumonia, STDs, etc. 6 types of infectious disease 94% of all deaths attributed to infectious disease - 4 types of infectious disease account for 80% of all deaths attributed to infectious diseases: respiratory infections, HIV/AIDS, tuberculosis, diarrheal diseases - 2 types of infectious disease account for 3-5% of all deaths attributed to infectious diseases: malaria, measles, tetanus ¼ of worldwide deaths Pathogens: viruses, bacteria, fundi, protists, helminths (group of parasitic worms)

Zika virus disease

A disease caused by a pathogen that causes fetuses to be born with unusually small heads and damaged brains - Carried by mosquitoes and transmitted to humans when bitten by mosquito or through sexual contact with an infected person - Health effects: rashes, fevers, headaches (mild) - Virus can be passed from pregnant mother to fetuses→ infected fetus with small head and brain damage (major) - Very recent emerging infectious disease - First discovered in a monkey in Uganda - Present in Central America, South America, Central Africa, Southeast Asia - No current treatment for virus; more focused on reducing mosquito populations

Mad cow disease

A disease in which prions mutate into deadly pathogens and slowly damage a cow's nervous system (aka BSE) - Prion: A small, beneficial protein that occasionally mutates into a pathogen (Not well understood; represent new category of pathogen) - Cow loses coordination of its body (glazed eyes, body tremors), then dying - Could be transmitted to humans who eat meat from an infected cow - Prions hard to destroy by cooking (unlike other harmful bacteria) - Infected humans develop CJD (Creutzfeldt-Jakob Disease) and suffered similar fates to an infected cow - The prions can exist in humans for many years before getting symptoms **Transmission requires an uninfected cow to consume the nervous system of an infected cow Control - Europe temporarily banned British beef imports and destroyed thousands of cattle - New rules: forbid feeding of animal remains to cattle

Acute disease

A disease that rapidly impairs the functioning of an organism/ human body Ex. Ebola hemorrhagic fever

Chronic disease

A disease that slowly impairs the functioning of an organism/ human body Ex. heart disease and most cancers Develop over several decades/ a while

Tuberculosis (TB)

A highly contagious disease caused by the bacterium Mycobacterium tuberculosis that primarily infects the lungs - Spreads when a person coughs and expels the bacteria into the air (bacteria can persist in air for several hours and infects people who inhale) - Health effects: feeling weak, sweating at night, coughing up blood - People can be infected BUT not develop the disease itself - Estimated that ⅓ of world is infected with TB - Control spread using antibiotics - Remains leading cause of death by disease in developing world (less medicine available or affordable) Those who DO receive the medicine sometimes don't take full course at prescribed dose: when someone stops taking antibiotics before the last bacteria has been killed... 1. Pathogen can quickly rebuild population inside body 2. The last few bacteria are most drug-resistant→ selects for drug-resistant strains Strains are major concern in parts of Africa and Russia bc they're harder to kill and require newer and more expensive antibiotics

Primary pollutants

A polluting compound that comes directly out of a smokestack, exhaust pipe, or natural emission source CO, CO2, SO2, NOx, PM, many VOCs Ex. for VOCs: as gasoline burns in a car, it volatilizes from a liquid to a vapor, some of which is emitted from the exhaust pipe in an uncombusted form, and the VOC becomes a primary air pollutant (usually when the car is not operating efficiently)

"Innocent-until-proven guilty" principle

A principle based on the belief that a potential hazard should not be considered an actual hazard until the scientific data definitively demonstrate that it actually causes harm (US) - Allows beneficial chemicals to be sold sooner - Downside: harmful chemicals can affect humans or wildlife for decades before sufficient scientific evidence accumulates to confirm they are harmful

Precautionary principle

A principle based on the belief that action should be taken against a plausible environmental hazard (Europe) - Need scientific evidence that demonstrates a plausible risk - The chemical then must be further tested to see if it is safe and usable - Allows fewer harmful chemicals to enter the environment - Downside: slower pace and reduce financial motivation to invest in research for new chemicals - Used for asbestos (banned)

Formation of Stratospheric ozone

A series of chemical reactions produce a molecule: ozone (O3) STEP 1: UV-C radiation breaks the molecular bond holding an oxygen molecule together: O2+ UV-C → O + O - Happens to only a few O2 molecules at any given time. The vast majority of the O2 in the atmosphere remains in the form O2 STEP 2: A free oxygen atom (O) produced in the first reaction encounters an oxygen molecule, and they form ozone O + O2 → O3 - Both UV-B and UV-C radiation can break a bond in this new ozone molecule, forming molecular oxygen and a free oxygen atom once again O3+ UV-B or UV-C → O2 + O Thus, formation of ozone in the presence of sunlight and its subsequent breakdown is a cycle that can occur indefinitely as there as there is UV energy entering the atmosphere - Under normal conditions, the amount of ozone in the stratosphere remains at steady state

Thermal inversions

A situation in which a relatively warm layer of air at mid-altitude covers a layer of cold, dense air below - Inversion layer: The layer of warm air that traps emissions in a thermal inversion - Bc the air closest to Earth's surface is more dense than the air above it, the cool air and the pollutants within it DO NOT rise Inversion layer TRAPS emissions, causing them to accumulate them and cause a severe pollution event (trap high concentrations of pollution at ground level) - Thermal inversions are common in some cities where high concentrations of vehicle exhaust and industrial emissions are easily trapped by the inversion layer - Thermal inversions can lead to other forms of pollution too Ex. In northern China: using individual coal-burning stoves for heat after a cold spell caused a temperature inversion to trap the CO and PM from the coal used, causing carbon monoxide poisoning respiratory ailments

Synergistic interaction

A situation in which two risks together can cause more harm than expected based on the separate effects of each risk alone - Ex. Health effects of asbestos can be much higher if they also smoke

SARS and MERS

A type of flu caused by a coronavirus (Severe acute respiratory syndrome) - Health effects: respiratory symptoms - Unusual form of pneumonia spreading through humans in Southeast Asia - Can spread from person to person; can cause outbreaks MERS (another coronavirus): Middle Eastern Respiratory Syndrome - Appeared on Arabian Peninsula - May have originated from an animal source

Human Immunodeficiency Virus (HIV)

A type of virus that causes AIDS (acquired Immune Deficiency Syndrome) - 1970s: rare types of pneumonia and cancer appeared in people with weak immune systems - Health effects: AIDS was responsible for weakened immune systems, caused by HIV - Spread through sexual contact and blood transfusions, from mothers to fetuses, and among drug users who share unsanitized needles - Origin: chimpanzees (virus spread when hunters ate their meat) - Control spread using new antiviral drugs (maintain low HIV populations inside human body→ extends life for those infected w/ HIV) - Expensive: not affordable for people in developing countries

West Nile Virus

A virus that lives in hundreds of species of birds and is transmitted among birds by mosquitoes (vectors) - Can be highly lethal to some bird species (blue jays, crows, robins); most species survive - Reported that virus could sometimes infect horses and humans bitten by mosquitoes - First human case: West Nile region of Uganda - Health effects: brain inflammation, death - In US: first appeared in NYC and quickly spread throughout country - Control by combating mosquito populations and protect against mosquito bites

Why acid deposition may affect regions far from the source of pollutants

Acid deposition crosses international borders between US and Canada and is carried from England, Germany, Netherlands, to Scandinavia Mobility: precursors to acid deposition in one region may have significant impact on another - Recently, observed acid deposition along West Coast of US is believed to be result of coal combustion in China (**recent increases in acid deposition in western US are due to increased emissions in China**) - Sulfur and nitrogen oxides released in China and are carried by prevailing westerlies/winds→ deposited on western US ground in rain and snow and intercepted by vegetation

Why rain is "naturally" slightly acidic

All rain is "naturally" slightly acidic bc the reaction between water and atmospheric CO2 lowers the pH of precipitation from neutral (7.0) to 5.6 (more acidic) - Naturally acidic due to dissolved CO2 - Rain dissolves CO2 from the atmosphere to form carbonic acid (weak acid giving natural rain pH of 6) - Burning fossil fuels make stronger acids get in rain to form acid rain with pH as low as 3 6 → 3 pH = 1000x more acidic CO2 and SO2 are produced when fossil fuels containing sulfur are burned - In the presence of sunlight, SO2 reacts with more O2 to form SO3 → dissolves in rain → sulfuric acid (H2SO4)

Bioaccumulation

An increased concentration of a chemical within an organism over time Begins when an individual is exposed to small amounts of a chemical from the environment and incorporates the chemical into its tissues (typically fat tissues) Ex. mercury in fish

Plague

An infectious disease caused by a bacterium that is carried by fleas - Fleas attach to roderns (mice and rats) → lots of mobility for fleas - Most historical: bubonic plague/ Black Death - Health effects: swollen glands, black spots on skin, death - Still occasional small outbreaks of plague around the world today - Ex. small number of rodents in American Southwest continue to carry the bacteria - Control spread using antibiotics

Malaria

An infectious disease caused by one of several species of protists in the genus - Malaria parasite spends one stage of its life inside mosquito and another inside human - Spread from mosquito to human - Health effects: flu like symptoms - Regions hit hardest: sub-Saharan Africa, Asia, Middle East, Central + South America Eradicated in US - Control spread using insecticides (DDT), although ineffective in many parts of the world

Emergent infectious diseases

An infectious disease that has not been previously described or has not been common for at least 20 years - The rapid movement of people can cause unexpected pandemics - Many come from pathogens that jump from animal hosts to humans - Can mutate rapidly and eventually produce a genotype that can infect humans - NOT primarily caused by mutations of known viruses - Since the 1970s, emergent infectious diseases have been appearing throughout the world at a rate of appx. one per year Ex. HIV/AIDs, Ebola, mad cow disease, bird flu, SARS, West Nile Virus, human monkeypox, cholera, lyme disease, Ebola, Zika virus etc.

Ebola Hemorrhagic Diseases

An infectious disease with high death rates, caused by several species of Ebola viruses First discovered in Congo near Ebola River→ infected 100s of humans and other primates in central Africa (sporadic infections) - Kills a large percentage of those infected (50-90% death rate) - Health effects: fever, vomiting, internal/external bleeding, death - Control using experimental drugs; New experimental Ebola vaccine - Natural source of Ebola virus has been difficult to determine (virus leaves no primate hosts for the virus bc kills primates at high rates) - BUT researchers then discovered fruit bats carrying Ebola virus were likely reservoir species that spread virus to primates - Reservoir species: host infected, but will not get the disease itself (many bats)

Disease

Any impaired function of the body with a characteristic set of symptoms ¾ of human deaths worldwide caused by diseases

Bird Flu

Bird Flu: A type of flu caused by the H5N1 virus - Emerged from Asia; jumps from birds to people (close contact with birds) - Rarely deadly to wild birds, but causes domesticated birds (chickens, ducks, turkeys) to be very sick and die - Humans have very few defenses against virus (bc no evolution history with virus) - Govs responded by destroying many infected birds - Today, not easily passed among people (but if future mutations makes transmission easier→ potential to kill 150 million people)

Breakdown of Stratospheric ozone

CFCs: chemical essential to modern life (fridge, air conditioning) that used to be considered "safe" bc non toxic + non flammable. They actually promote breakdown of the strat. Ozone - CFCs introduce chlorine (Cl) intro stratosphere When Cl is present, it can attach to an O2 atom in an ozone molecule→ break bond O3 + Cl→ ClO + O2 ClO then reacts with a free O2 atom (O), pulling the O2 from the ClO to produce free chlorine again ClO + O → Cl + O2 We see that chlorine starts out AND ends up as a free Cl atom (Cl is a catalyst) - In contrast: an ozone molecule and a free O2 atom are converted into two O2 molecules - Catalyst: A substance that aids a reaction but does not get used up itself - A single chlorine atom can catalyze the breakdown of as many as 100,000 ozone molecules until a chlorine atom finds another and stops RESULT: Ozone molecules no longer available to absorb incoming UV-B radiation→ UV-B can reach Earth's surface, causing harm to biological organisms

London, England (Explain the conditions that led to the Great Smog of 1952. What type of smog formed here?)

Caused by industrial pollution and high-pressure weather conditions (caused deaths) London-type smog (grey, sulfurous, industrial smog)

Chemical persistence

Chemical persistence: The length of time a chemical remains in the environment Depends on a number of factors: temperature, pH, whether the chemical is in water or soil, whether it can be degraded by sunlight or broken down by microbes - Measured by observing the time needed for a chemical to degrade to half its original concentration (half-life of the chemical) - DDT has a half-life of up to 30 years (even after DDT is no longer sprayed in an area, half of the chemical that was absorbed in the soil would still be present after 30 years, etc.) - DDT: endocrine disruptor that is highly persistent; effective at combating malaria

DDT Accumulation

Chemicals that are soluble in fats and oils can also be stored in the fatty tissues of animals - DDT (along with Atrazine) are examples of endocrine disrupters - DDT accumulates in fatty tissues of aquatic birds (like pelicans and eagles) - it's a POP - DDT: insecticide used to kill pests in agriculture and mosquitoes that carry malaria - Not soluble in water→ when sprayed over water, it quickly binds to particulates in the water and the underlying soil OR is quickly taken up by tiny zooplankton that act as primary consumers on algae - Very low concentrations of DDT in water bioaccumulates in a low trophic group (i.e. plankton) → consumption causes upward movement of the chemical where it is accumulated in the bodies at each trophic level→ concentration magnifies to the point where it is more concentrated in the top predator - Low concentrations of methyl mercury accumulates in fish when they drink water and consume food that contains mercury Fish stores mercury in its fat over time and mercury accumulates

Carcinogens

Chemicals that cause cancer - Cause cell damage and lead to uncontrolled growth of these cells (**either by interfering w/ normal metabolic processes of the cell OR by damaging the genetic material of the cell**) - Mutagens: a type of carcinogen that causes damage to the genetic material of a cell (not all mutagens are carcinogens though) - Ex. asbestos, radon, formaldehyde, arsenic, vinyl chloride, chemicals found in tobacco

Neurotoxins

Chemicals that disrupt the nervous systems of animals - Ex. insecticides (interfere with insect's ability to control nerve transmissions) - Animals can become paralyzed, be unable to obtain O2, and quickly die - Lead and mercury: very harmful heavy metals that can damage human kidneys, brain, liver, and nervous system, impaired earning - Gov required gradual elimination of lead in gasoline and paint (lead exposure decreased); lead contamination in children still remains a serious problem in low-income neighborhoods bc old lead paint in buildings

Teratogens

Chemicals that interfere with the normal development of embryos or fetuses - Thalidomide (infamous): drug prescribed to pregnant women during late 1950s to combat morning sickness BUT this led to children birthed with defects - Alcohol (most common modern): excessive alcohol consumption reduces fetus growth and damages brain and nervous system of fetus (fetal alcohol syndrome) - Why women shouldn't consume alcohol when pregnant

Greatest effects of acid deposition have been on aquatic ecosystems - forests, lakes, streams

Decreased pH can also affect food sources of aquatic organisms→ INDIRECT effects at several trophic levels - Land: trees (i.e. red spruce) at high elevations of northeastern US harmed by acid deposition due to acidity and nitrate and sulfate ions

Explain how indoor air pollution differs in developing and developed countries (e.g., main sources) - Developed

Developed - Houses sealed up for greater energy efficiency are often the causes of radon, CO, and VOC exposure and accumulation for people who spend lots of time indoors - Increasing number of materials made from plastics and petroleum-based materials give off chemical vapors

Explain how indoor air pollution differs in developing and developed countries (e.g., main sources) - Developing

Developing - Many people burn wood, animal manure, coal indoors (lack proper mix of fuel and air to allow complete combustion) - CO from combustion for cooking is the biggest problem - No ventilation in homes: CO and PMs lead to indoor air pollution - Risk of acute respiratory infections, pneumonia, bronchitis, cancer - Most deaths (90%) related to indoor air pollution occur in developing countries

Why air pollution poses a greater health risk to children

Developing countries: Women and children receive greatest exposure to CO and PM bc they cook When biomass is used for cooking, concentrations of PM in the home are very high

Difficult to determine whether an effect is direct or indirect (remediation/ stopping is challenging)

Direct effects: decrease in pH of lake water Lower pH of lakes and streams cause decreased species diversity Species unable to survive and reproduce due to narrow range of environmental conditions Indirect effects: mobilization of metals Lower pH leads to mobilization of metal Metals (aluminum and mercury) bound in organic or inorganic compounds in soils are released into surface water→ exposure can impair physiological functioning of aquatic organisms and species loss

Problem of Evolving Microbes

Diseases can have both genetic and environmental causes. These two factors can interact, especially for diseases caused by pathogens like fungi, bacteria, viruses These pathogens have evolved a wide variety of pathways for infecting humans: transmission through food, water, air, other humans, other domesticated + wild animals

Dose-response studies

Dose-response studies: a study that exposes organisms (animals or plants) to different amounts of a chemical and then observes a variety of possible responses, including mortality or changes in behavior or reproduction - Ex. dose-response studies of aquatic animals (i.e. tadpoles) are used to determine concentrations of various pesticides that cause many of them to die - Concentration of considered chemicals can be measured in air, water, food OR dose of a chemical (amount that an organism absorbs/consumes) - Most dose-response studies last for 1-4 days for efficiency Acute studies: an experiment that exposes organism to an environmental hazard for a short duration Chronic studies: an experiment that exposes organism to an environmental hazard for a long duration (examine long term effects of chemicals) - Could last from the time an organism is very young to when it is old enough to reproduce - Most commonly measure mortality as a response - At the end of an experiment, they count how many individuals die after exposure to each concentration - Graphed data generally follow an S-shaped curve (lower concentrations = less deaths; higher concentrations = more deaths) - Threshold = the dose at which an effect can be detected - OTHER harmful effects: chemicals acting as a teratogen, carcinogen, or neurotoxin - Sublethal effects: When exposure of a chemical impairs its behavior, physiology, or reproduction (not death) - In these cases, the experiments are conducted to determine the ED50

Beijing (Discuss the problem that China has with its growing economy and people's desire to own cars. Strategies?)

During the 2008 Beijing Olympics, the government successfully expanded public transportation networks, imposed motor vehicle restrictions, and temporarily shut down a number of industries as a way to reduce photochemical smog and improve visibility For a short period, the air pollution control measures were successful, but long-term improvements in air quality in China have been harder to achieve

ED50

ED50: The effective dose that causes 50% of the individuals in a dose-response study to display a harmful (but nonlethal) effect

Describe the mechanism by which endocrine disruptors impair normal endocrine system function

Endocrine disruptors bind to receptor cells, or they can also mimic normal hormones, which cause the cell to respond in ways that are not beneficial to the organism

Epidemic and Pandemic

Epidemic: A situation in which a pathogen causes a rapid increase in disease - Ex. A fast-acting strain of influenza claimed the lives of 400 people in western Ohio Pandemic: An epidemic that occurs over a large geographic region - The rapid movement of people can cause unexpected pandemics

Particulate Matter Removal: Baghouse filters

Fabric filters remove almost 100% of PM emissions

Natural (tropospheric) ozone accumulation NO2 → NO + O → O + O2 → O3

From natural and anthropogenic sources Takes place during the day (sunlight) with very few VOCs present STEP 1: Nitrogen dioxide (NO2) splits to form nitrogen oxide (NO) and free oxygen atom (O) NO2 → NO + O STEP 2: Free oxygen atom (O) combines with diatomic oxygen (O2) to form ozone (O3) O + O2 → O3 In the presence of energy inputs from sunlight With abundant nitrogen dioxide and sunlight, ozone accumulates in atmosphere

Vapor recovery nozzles: Reduces VOCs

Gasoline vapors accumulate in vehicle fuel tanks above the liquid level→ when the tanks are filled, rising liquid forces these vapors to rise→ go into air Vapor recovery nozzles are fitted to gasoline pumps to capture these vapors - Vapors drawn in through holes in the side of the nozzle and travel through special hoses back to the main storage tank - Highly effective (prevent 95% of vapor escape)

Acid deposition effects on materials, agricultural lands, human health

Human-built structures: statues, monuments, buildings - Causes erosion: acid deposition reacts with building materials - Hydrogen ion (H+) interacts with limestone or marble (contains calcium carbonate) → Ca2+ (calcium ion) - Calcium carbonate is susceptible to deterioration from acid deposition and acids in the air - Calcium carbonate is partially dissolved: The more acidic the precipitation, the more hydrogen ions there are to interact with calcium carbonate - Erodes exposed painted surfaces (like automobile finishes) People are NOT harmed by direct contact with precipitation bc human skin is robust barrier - BUT human health is affected from SO2 and NOx

Mexico City (Geographic influence, strategies)

Instituted plans permitting automobiles to be driven only every other day (ex. those with license plates ending in odd numbers may be used on one day - alternate) Not really a big impact though

LD50

LD50: The lethal dose of a chemical that kills 50% of the individuals in a dose-response study - Helps assess relative toxicity of a chemical to a particular species (measures mortality) - Ex. can compare LD50 value of a new chemical with LD50 value of thousands of previously tested chemicals to determine whether the new chemical is more or less lethal to a given organism than other chemicals - Lower LD = more toxic the substance - Examine what proportion of the animals die at each dose: produce S-shaped curve - Threshold = the dose at which an effect can be detected - Conduction LD50 and ED50 studies on mice and rats can represent ALL mammals, etc.

Low-income vs high-income countries and human diseases

Low-income countries Require improvements in nutrition, wider availability of clean drinking water, proper sanitation High-income countries Promote healthier lifestyle: limiting excess food consumption and tobacco use All countries - Continued education to reduce spread of diseases (like HIV and TB) - Increased use of antiseptic cleaners designed to kill microbes like bacteria (antibacterial soaps - typically kill large proportion of harmful pathogens, but not all) Problems of antiseptic cleaners: - We are selecting for pathogens that posses a stronger resistance (promote evolution of bacterial-resistant pathogens) - Products also move through wastewater and into streams, rivers, lakes - No evidence antiseptic cleaners are more effective than plain soap and water or are safe for people to use on a daily basis

Affluence changes the major health risk factor for chronic disease

Low-income countries: top risk factors leading to chronic disease are associated with poverty, underweight children, unsafe drinking water, poor sanitation, malnutrition - Malnutrition: caused by political upheaval, poverty, high food prices - Nearly ½ children under 5 years old die from pneumonia and ¾ of children who die from diarrhea are malnourished - Children with good nutrition are better able to fight infectious disease and survive High-income countries: people can afford better nutrition and proper sanitation, so fewer die at a young age from diseases like pneumonia and diarrhea - Risk factors: tobacco, less-active lifestyles, poor nutrition, overeating leading to high blood pressure and obesity, poor urban air quality - Out of malnutrition, indoor smoke, HIV, and HBP: *High blood pressure* is one of the ten leading health risks in developed countries

SOURCES of pollutants: secondary pollutants

Nitric acid (HNO3): exhaust pipes of motor vehicles - Air taken in to combust the fuel is nearly 80% nitrogen→ exhaust gasses contain significant amounts of nitrogen oxides - Nitrogen oxides react with O2 in the air→ nitric acid - If the rain falls on limestone (alkaline), the acidity may be neutralized If the rain falls on soils and vegetation (neutral or acid), it may cause damage - Metals, like aluminum or mercury, become soluble in acidic soil→ get taken up by living organisms (take place of essential metals like zinc and iron) Sulfuric acid (H2SO4): burning of coal and oil mainly in power stations - Burning of fossil fuels

Noninfectious diseases

Noninfectious diseases are NOT caused by pathogens Most cardiovascular diseases, respiratory + digestive diseases, most cancers

Without thermal inversions (normal)

Normally: temperature decreases as altitude increases (warmest air closest to Earth) Warm air is less dense than colder air above it, so it can easily rise and disperse pollutants into the upper atmosphere (reduce and dilute pollutants)

Acid deposition formation

Occurs over a number of days, and the pollutants may travel 1000+ km 1. Nitrogen oxides (NO and NO2) and sulfur dioxide (SO2) are released into the atmosphere by natural and anthropogenic combustion processes 2. Series of reactions with O2 and water→ primary pollutants^ transformed into secondary pollutants: nitric acid (HNO3) and sulfuric acid (H2SO4) 3. These compounds break down further, producing nitrate and sulfate (inorganic compounds) and hydrogen ions (H+) that generate the acidity in acid deposition 4. Eventually, the secondary acidifying pollutants^ are washed out of the air and deposited either as precipitation or in dry form on vegetation, soil, water

Explain how the solubility of a chemical influences its potential for bioaccumulation or biomagnification (e.g., DDT, Mercury, PCBs)

Once we know the potential routes of exposure, we can then determine the chemical's solubility and its potential for bioaccumulation and biomagnification Solubility: How well a chemical dissolves in a liquid (movement of liquid depends on this) - When a chemical is highly soluble in water, it can be washed off surfaces, percolate into groundwater, and run off into surface waters (rivers and lakes) - Chemicals that are soluble in fats and oils (not soluble in water) tend not to be found percolating into the groundwater or running off into surface waters - Can be found in higher concentrations bound to soils (including the benthic soils that underlie bodies of water)

Math: If CO emissions decreased from 145 million tons annually to 80 million tons annually, by what percentage have emissions been reduced?

Percent change: (old - new)/old = (145-80)/145 = 0.448 = 45% decrease

Math with LD50: If 1 mg/kg of mass of a pesticide is the LD50 for rats in an experiment, what would be considered the safe exposure for humans?

Rats: LD50/10 Humans: LD50/1000 So...for humans, it would be 1/1000 = 0.001 mg/kg

Particulate Matter Removal

Reduces PM (and sometimes SOx); Increases CO2 - PM removal is most common means of pollution control - Sometimes removes sulfur along with the PM - All three devices use additional energy and require more fuel→ increase CO2 emissions - Most devices use electricity, BUT that generates additional pollution

Different studies

Retrospective study: A study that monitors people who have become exposed to an environmental hazard (i.e. harmful chemical), as some time in the past Prospective study: A study that monitors people who have become exposed to an environmental hazard (i.e. harmful chemical), as some time in the future - Can be difficult bc a participant's habits (like tobacco use) can also be associated with man other risk factors, such as socioeconomic status - Monitors individuals who might be exposed to harmful chemicals in the future

Identify the five major routes of exposure to environmental contaminants

Route of exposure: The way in which an individual might come into contact with an environmental hazard, such as a chemical 1. Exposure to chemicals 2.Exposure from air 3. Exposure from water used for drinking, bathing, swimming 4. Exposure from food 5. Exposure from the environments of places where people live, work, or visit

Safe levels for ingestion (LD50)

Scientists determine safe levels for rodents to ingest by LD50 / 10 Scientists determine safe levels for humans to ingest by LD50 / 1000

Industrial smog

Smog that is dominated by SO2 and sulfate compounds Aka London-type smog (Gray smog, sulfurous smog) Gray, burning coal, accumulates in winter (more heating in homes), SOx and PM

Photochemical smog

Smog that is dominated by oxidants, such as ozone (Observed in cities, esp Asia) Aka Los Angeles-type Smog (Brown smog) Reddish-brown, combustion engines, worst in summer (pollutants react with sunlight), VOCS, NOx, O3, CO - A number of pollutants are involved and they undergo transformations in atmosphere involving sunlight, water, and presence of VOCs - Atmospheric brown cloud: combination of PM and ozone (Derived from combustion of fossil fuel and burning biomass) - Brown tint = caused by presence of black or brown light-absorbing carbon particles and/or nitrogen dioxide - High levels of photochemical smog are due to nitrogen dioxide and VOCs (NOT sulfur dioxide)

Importance of stratospheric ozone to life on Earth

Stratospheric ozone forms a necessary, protective shield against from the Sun - Absorbs UV light and prevents harmful UV radiation from reaching Earth - Occurs higher in the atmosphere than troposphere - Ability to absorb UV radiation and shield surface below makes stratospheric ozone important to life on Earth - Decreased strat. ozone leads to rise in UV-B radiation reaching Earth's surface

Swine Flu

Swine Flu: A type of flu caused by the H1N1 virus - Ex. Spanish Flu - Normally infects only pigs, BUT can jump from pigs to humans - Control using vaccines (prevent infection) and drugs (combat virus in infected person)

Natural (tropospheric) ozone destruction O3 + NO → O2 + NO2

Takes place a few hours later, when sunlight intensity decreases and NO2 is still present in atmosphere (latter part of day and evening) Ozone combines with nitrogen oxide (NO) and re-forms into O2 + NO2 O3 + NO → O2 + NO2

Major effects of ozone depletion (consider ecological impacts, agricultural impacts and human health effects)

The Sun radiates energy at many diff wavelengths (diff UV ranges) - UV-A: Low-energy UV radiation - UV-B and UV-C: Shorter, higher-energy wavelengths Exposure to UV-B - Increases risk of skin cancer and cataracts, eye problems, suppressed immune system - Increase in skin cancer esp. near Antarctic ozone hole (i.e. Chile + Australia) - Harmful to plant cells (reduces ability to perform photosynthesis) - Loss of phytoplankton: microscopic algae that form the base of many marine food chains (depletes fisheries) - Overall: Harmful to entire biological communities and ecosystem productivity

No-observed-effect level (NOEL)

The highest concentration of a chemical that causes no lethal or sublethal effects Indicates how much of a chemical an organism can experience with NO harmful effect

Biomagnification

The increase in chemical concentration in animal tissues as the chemical moves up the food chain The original concentration in the environment is magnified to occur at a much higher concentration in the top predator of the community Ex. The case of DDT accumulation