APES Unit 7

Clean Air Act (1970)

identified 6 criteria air pollutants that the EPA is required to set acceptable limits for, monitor, and enforce

Sulfur dioxide pollutant sources and effects

source: Coal combustion (electricity)

effects:

• respiratory irritant

• smog

• acid precipitation

Nitrogen dioxide pollutant sources and effects

sources: all FF combustions and gas escapes

effects:

• O3 ozone formation

• photochem smog

• acid rain

carbon monoxide pollutant

sources: incomplete combustion

• furnace (get carbon monoxide detectors)

• generator (have it outside)

effects:

• ozone formation

• lethal to humans

  • less oxygen goes to organs (hemoglobin) → suffocation

  • don’t smell or taste it

Particulate Matter pollutant (PM)

floating particles in the air

sources: FF and biomass combustion

effects:

• respiratory irritant → black lung

• smog

Ozone pollutant

pollutant at ground level → necessary in atmosphere

filters and shields UV rays, but it’s reactive and an irritant at ground level

source: Photochemical oxidation of NO

effects:

• respiratory irritant

• smog

• Damaging to plant stomata, limiting growth

Lead pollutant

leaded vs unleaded gas

source: metal plants, waste incineration

effects: neurotoxicant

Carbon dioxide DOES NOT classify as an air pollutant (one of the six)

true → we produce it, it’s not as dangerous as the 6 pollutants, but can cause damage.

Greenhouse gas. Leads to Earth warming then human health consequences

• Not toxic to organisms to breath

• Not damaging to lungs/eyes

• Doesn’t lead to smog

Coal combustion and pollutant release

releases more air pollutants than other FFs

releases CO, CO2, SO2, NO, PM, and toxic metals like (mercury, arsenic, lead)

How can Nitrogen oxides (NOx) be released? What can NO release?

released by combustion (FFs and biomass)

• sun’s rays can split NO2 → NO + O then O reacts with earth O2 and makes O3

• sunlight converts NO₂ back into NO

ozone action day

hot, dry, sunny days when ground-level ozone is forecast to reach levels of health concern

alert will be sent out to encourage not using any gasoline equipment between about 10am-2pm

EPA and lead

• EPA requires catalytic converters in cars (exhaust system w/ special metals) → reduced emissions for cleaner air

• catalytic converters have expensive metals

• they restrict air flow & horsepower

• lead damages catalytic converters

Primary Air Pollutants

formed first

emitted directly from sources like PPs or natural sources

NO_x, CO, CO₂*, VOCs, SO₂, PM, hydrocarbons

Secondary Air Pollutants

formed because you formed primary

primary pollutants that transformed in presence of sunlight, water, O2

• occur during day

• O₃ (Ozone); Sulfuric acid (H₂SO₄); sulfate (SO₄^2-); Nitric acid (HNO₃); & nitrate (NO₃^-)

what is smog

decreased visibility

fog + smoke = smog

impacts of SO2

• Respiratory irritant → inflammation of bronchioles, lungs; worsens asthma & bronchitis

• smog

• acid rain

PM often carries

toxic metals

• mercury

• arsenic

• lead

Environmental and human health impacts of Nitrogen oxides

• respiratory irritant

• O3 formation → photochemical smog

• Combines with water & O2 in atm. to form nitric acid → acid precipitation

Volatile organic compounds (VOCs)

• hydrocarbons that bind with NO & form photochemical oxidants

• can smell these → like paint

• Carbon-based compounds that volatilize (evaporate) easily → makes them “smelly”

Photochemical smog conditions

• more O3 formation

• hotter air temp causes more O3 formation & evaporation of VOCs → smog formation

What is a common source of NO2

cars and vehicles

Normal O3 formation

• peaks w/ direct sunlight (afternoon)

• car exhaust

• photochemical ozone formation

Photochemical smog formation

to reduce PSF, reduce VOCs in air

• VOCs bond with NO to form photochemical oxidants

• photochemical ozone formation

• O₃ combines with photochem. oxidants (NO + VOCS) to form photochemical smog

Factors that increase smog formation

• intense sunlight

• more industry

• warmer temps

• urban areas

• more traffic

• more electricity demand

• higher VOC emissions

impacts of smog

• reduces sunlight and photosynthesis (plant damage)

• respiratory irritant → higher healthcare costs

• loss of workers due to sickness

• decreased agricultural yields since less sunlight reaches crops AND damages plant stomata

reduction of smog

• decrease number of vehicles on road

• electric cars → don’t burn gas

• public transportation/carpooling

• biking and walking → more city planning

• more renewable sources

• natural gas release instead of coal

precursors of photochemical smog formation

NO2, VOCs, and O3

how does tropospheric ozone levels normally decline overnight

O3 reacts with NO to form NO2 and O2 once again

Urban Heat Island Effect

warmer temperature than surrounding areas due to lower albedo (absorb more sun’s energy)

Thermal Inversion

cooler air mass becomes trapped near earth’s surface (density)

colder = more dense

• Due to a warm front moving in over it

• Or due to hot urban surfaces cooling overnight

• traps cold air and any pollutants with it → like garage door

4 natural sources of air pollutants

What do they release/emit

• lightning strikes

  • convert N₂ in atm. to NO_x

• forest fires

  • combustion of biomass

  • releases CO, PM, NO_x, CO2, and H2O

• plants

  • especially conifers

  • emit VOCs

• volcanes

  • SO2, PM, CO, NO_x

Natural Sources of CO2 & PM

• respiration

• natural PM sources

• aerobic decomposition

• anaerobic decomposition

respiration

All living things (plants included) release CO₂

natural PM sources

Sea salt, pollen, ash from forest fires & volcanoes

dust (windborne soil) → Leads to haze

Aerobic Decomposition

Decomposition of organic matter by bacteria & decomposers in the presence of oxygen → releases CO₂

Anaerobic Decomposition

Decomposition of organic matter by bacteria & decomposers in low or oxygen-free conditions → releases CH₄ (methane)

Particulate Matter

solid or liquid particles suspended in air

Developing countries

• use more subsistence fuels such as wood, manure, charcoal (biomass)

• release CO, PM, NO_x, VOCs ( can also cause deforestation)

• often combusted indoors with poor ventilation

• causes lots of death annually

developed countries

• use more commercial fuels (coal, oil, natural gas) supplied by utilities

• typically burned in closed, well ventilated furnaces, stoves, etc.

• adhesives in furniture, cleaning supplies, insulation, lead paint all have chemicals that cause air pollutants

Asbestos

long, silicate particle previously used in insulation → respiratory irritant

• phased out of use → in some old buildings

• Not dangerous until insulation is disturbed and asbestos particles enter air

• needs to be removed by trained professionals

Carbon Monoxide effects

causes suffocation due to CO binding to hemoglobin in blood, displacing O₂

• Lethal to humans in high concentrations

  • poor ventilation

  • odorless and colorless - hard to detect

developed nations w/ carbon monoxide

• CO released into home by malfunctioning natural gas furnace ventilation

  • Can be detected by carbon monoxide detectors (similar to smoke detectors)

developing nations w/ carbon monoxide

CO emitted from indoor biomass combustion for heating/cooking

VOCs

Chemicals used in variety of home products that easily vaporize, enter air, and irritates human respiratory system

What common things have VOCs in them

• chemicals used to glue carpet down, hold furniture together, seal panels

  • formaldehyde used in common adhesives (new carpet smell)

• Common household cleaners and deodorizers like febreeze

• plastics and fabrics

Radon Gas

Radioactive gas released by decay of uranium naturally found in rocks underground (granite especially) → released into cracks of house through basement

Causes and effects of radon gas

Solutions

Causes

• enters homes through cracks in foundation, then comes through basement/foundation of home

• can seep into groundwater sources & enter body through drinking water

  Effects

• causes lung cancer after smoking

  Solutions

• test homes w radon monitor

• seal cracks in foundation

Dust and mold

Natural indoor air pollutants that is a respiratory irritant

Dust and mold causes, effects, and solutions

• dust settles in homes naturally, disturbed by movement → enters air and then respiratory tract

• mold develops in dark and damp areas, not well ventilated (under sinks/showers, behind panels in walls and ceiling)

• Black mold is a class of mold that releases spores into air → extremely harmful to respiratory system

  solutions

• physically clean mold out and fix the water leak or ventilation issue that lead to mold forming

Where can lead be found? What are the effects and solutions?

• found in paint in old homes

• paint chips can be eaten by small children or inhaled as dust

• lead water pipes can release into water (less common than paint)

• damages central nervous system → kids brains are still developing and they’re small in size

• replace w/ city or copper pipes

How to reduce emissions and air pollutants

• drive less, walk more, bike more, use bus more

• conserve electricity

• eat more plants

• use renewable energy sources (solar, wind, hydro)

CAFE (Corporate Average Fuel Economy) vehicle standards

• requires U.S. vehicles to meet certain average fuel

• requires manufacturers to make more efficient vehicles → burn less gasoline and release less pollutants

Pollutions Credits

• Companies that reduce emissions well below EPA-set levels will earn pollution credits

  • They can sell these to companies that release more than acceptable levels

Vapor Recovery Nozzle

on gas pumps

• Capture hydrocarbon VOCs released from gasoline fumes during refueling

  • Separate tube inside nozzle captures vapors & returns them to underground storage tank beneath the gas station

  • Reduces VOCs, which contribute to smog & irritate resp. tracts

  • Also reduces benzene (carcinogen) released from gasoline vapors

Catalytic Converter

• Required on all vehicles after 1975

• Contains metals (platinum & palladium) that bind to NO_x and CO

CC converts NO_x, CO, and other hydrocarbons into CO₂, N₂, O₂, and H₂O → changes them into less harmful molecules

Crushed Limestone

• reduces SO₂ from coal power plants

  • Crushed coal mixed with limestone (calcium carbonate) before being burned in boiler

  • chemical reaction → Calcium carbonate, less SO2

  • Can pump air into it to make it go faster

Wet and Dry scrubbers

dry scrubber → large tube filled w chemicals to neutralize pollutants

wet scrubber → wash pollutants out of air and neutralize pollutants

Reducing PM - Electrostatic Precipitator

air that comes out is so much cleaner → expensive to build and maintain. PM taken to landfill

Reducing PM - Baghouse Filter

air that comes out is so much cleaner → expensive to build and maintain. PM disposed in landfill

Acid pH scale

0-7 pH

the lower the pH, the stronger the acid

H+

Sources of NO_x

• vehicle emissions

• diesel generators

• coal

• PPs

Sources of SO₂

• Coal PPs

• metal factories

• vehicles that burn diesel fuel

Base on pH scale

7-14

OH-

the higher the pH, the stronger the base

when acid meets base, it neutralizes (H₂O)

how to limit acid rain

• Reduces NO_x & SO₂ emissions and reduces acid deposition

  • Higher CAFE Standards (auto-industry)

  • More public transit

  • Renewable energy sources 

  • More efficient electricity use

    • passage of Clean Air Act → acid deposition decreased

acid deposition

leeches heavy metals from soil and bring it into water. Slows growth of plants and animals living in soil or water

Environmental affects of acid rain

• pH increases → exceeds organisms’ range or tolerance → can’t survive

• Aquatic species have diff. pH tolerances

Mitigating (to fix) acid rain

• limestone

• limit SO2 and NOx primary pollutants

What causes urban noise pollution

Any noise loud enough can cause physiological stress (difficulty communicating, headaches, confusion) or hearing loss

• Construction

  • jack hammers, trucks, concrete pouring

• Transportation

  • cars, busses, trains

• Industrial activity

  • manufacturing plants

• Domestic activity

  • neighbor’s music, lawn mowing, home projects

Land wildlife effects from noise pollution

disrupts animal communication, migration, and damage hearing

can cause physiological stress and decrease hearing (can’t hear prey → less chance of survival)

Aquatic noise pollution

comes from the noise of ship engines, military sonar, and seismic air blasts from oil & gas surveying ships → physiological stress

Indicator species

can be surveyed and used to determine conditions of an ecosystem