intro to pollution

Sulfur Dioxide - aka SO2

Comes from Coal Combustion

Nitrogen Oxides - aka NOx

Comes from all combustion reactions with fossil fuels

Carbon monoxide - aka CO

Comes from combustion, breakdown of O3

Particulate matter - aka PM

Can come from many places but not limited to combustion and various biomass agents

Ozone - aka O3

Comes from photochemical oxidation of NO2

Lead - aka Pb

Metal plants, mining, and waste incineration

The Clean Air Act

Created in 1960, this was a piece of legislation that identified the 6 criteria air pollutants that the EPA is required to set acceptable limits for, monitor, and enforce

CO2

CO2 is the major greenhouse gas that the world is concerned about, however it is not one of the 6 criteria pollutants. CO2 does not directly lower the air quality for humans - Not toxic to breath - Not damaging to respiratory system - There is no secondary pollutant involved

Primary Pollutants

These are gasses that are released directly from the pollution source - The powerplant - Tail pipes of cars - Factories and other industrial complexes - Natural sources such as forest fires and volcanoes

Primary Pollutants Examples

NOx, CO, VOCs, SO2, PM, CO2 and various hydrocarbons

Secondary Pollutants

These are the products of chemical reactions of your primary pollutants with chemical such as water and oxygen, along with reactions to light from the sun

Secondary Pollutants Examples

Tropospheric Ozone (O3) - Acid Rains - Sulfuric Acid (H2SO4) - Nitric Acid (HNO3) - Smog

Coal

Coal releases more pollutants than all the other fossil fuels and it comprises somewhere around ~35% of the global electricity source

When burning coal

Releases CO, CO2, SO2, NOx, any toxic metals that were found in the deposits, such as, Mercury, Lead, Arsenic, and gives off Particulate Matter through ashes which can carry pieces of toxic compounds

Why do we care (Coal)

Respiratory irritants - Asthma, Bronchitis - Sulfur aerosols can block sunlight and reduce visibility - Smog - Combines with water and O2 to form acid rain

NOx

NOx is what we use to refer to any of the nitrogen oxides (NO and NO2)

Nitric Oxide (NO)

NO forms when N2 gas combines with O2 example: combustion reactions

NO to NO2

NO can then become NO2 by reacting with ozone or O2

NO2 Breakdown

Sunlight break down NO2 back into NO

Why do we care (NOx)

This is another respiratory irritant - Can lead to smog formation and creation of more tropospheric ozone - Acid rain

Leaded Gasoline

Lead was a common additive to gasoline before 1970 when the Clean Air act was formed

EPA Action

The EPA began to phase out lead because of the toxicity of the chemicals

Catalytic Converter

Vehicles made after 1974 have this little device called a catalytic converter which reduces the excess pollutant coming from burning gas

Lead Benefit

Lead made car engine run easier and improved performance from a “discovery” in 1921

Lead Harm

Lead is a neurotoxin which can lead to serious nervous system damage to humans - Children in particular have been linked to developmental problems, along with higher instances of heart disease and cancer rates in adults

Photochemical Smog

NO2 - Sunlight causes photochemical reaction and breaks this into NO and O - VOCs aka (Volatile Organic Compounds) - these bind with NO and form what is known as photochemical oxidants - O3 - the binding of the O atom from the breakdown of NO2 to O2 forming ozone

Smog Conditions

Add a little Sunlight and some Warmth - Drives the breakdown of NO2 - Hotter temps speed up the reaction and evaporation of VOCs

VOCs

These are carbon based compounds that can easily evaporate which makes them smell - Formaldehyde, cleaning fluids, paints which are oil based, and the favorite of cut grass

Daily Smog Formation

Cars emit high levels of NO2 on their way to work in the morning - As the day continues and the sun shines throughout the day, the morning emission breakdown - Late afternoon is when the sun is most potent and forms smog - After the sun has set, the excess O3 reacts with NO to form NO2 and O2 before the cycle repeats

Smog Formation Process

NO2 → NO + O (Sunlight) - O + O2 → O3 - VOCs bond with NO to form photochemical oxidants - O3 combines with photochemical oxidants to form photochemical smog

Factors That Increase Smog Form

Higher VOCs emissions (gas stations, laundromats, petrochem. & plastic factories) - Increased vehicle traffic; increases NO2 emissions & therefore O3 formation - More sunlight (summer, afternoon) = more O3 - Warmer temperature speeds evap. of VOCs and reactions that lead to O3

Urban Areas Smog

Urban areas have more smog due to more traffic, hotter temps due to low albedo of blacktop, more VOCs, and more electricity demand

Environmental Part

Reduced photosynthesis because the sun is blocked - Ozone damages the plant stomata and causes breathing problems in animals

Economic Part

Health care costs - Lost worker productivity esp for outdoor jobs - Decreased yield for crops

Human Part

Breathing problems

Reducing Smog

Decrease the number of vehicles on the road - Increase energy production from sources that do not have combustion reactions or use natural gas - Walk

Natural Gas

Natural Gas doesn’t produce much particulate matter, but does produce CO2

Thermal Inversion

A temperature inversion occurred when the cooler air was trapped in the valley and the emission of SOx, NOx, and Fluoride began to accumulate forming a thick smog

Donora Fluoride Fog

Occurred in 1948 in a town south of Pittsburgh in a valley near the Monongahela River system - The town was known for its Steel Zinc Smelting plant - Somewhere in the range of 20 people died and somewhere between 35-50% of people got sick out of ~14,000 - 10 years after the event, the mortality rates were still higher than normal

Great London Smog

Severe smog event caused by coal burning and weather conditions