Atmosphere and Pollutants

What does the atmosphere do?

• Houses the air that we breathe

• Cycles water and other important bio-geo chemicals

• Regulates global temperatures

• Filters dangerous solar radiation

What is the atmosphere composed of?

78% nitrogen, 21% oxygen, 1% other gases

Thermosphere

4th Layer [Uppermost]

• Exposed to the full energy of the sun, ionizing particles make it extremely hot.

• Temps high as 1800 degrees F.

• No clear boundary into space. Atmosphere just becomes thinner and thinner until there is just no more gas.

Mesosphere

3rd Layer

• As we move away from the ozone layer, temperatures decrease. In the bottom half of the mesosphere, as altitude increases, temperatures decrease (as low as -112 degrees). Coldest layer.

• However, in the top half, there is a rapid temperature increase.

• Meteors that enter the atmosphere rarely make it past the mesosphere without burning up.

Ozone (Upper Stratosphere)

• Contains large O3 molecules which absorb, store, reflect huge amounts of solar radiation.

• Dynamic equilibrium - ozone is continuously added and removed. In both formation and destruction of ozone, radiation is absorbed.

• Absorbs about 98% of UV light.

  • "Good up high, but bad nearby".

What has happened to the ozone layer since the mid-1980s?

• It has begun to thin due to chloroflourocarbons (CFCs).

• CFCs contain carbon, fluorine, and chlorine, found in aerosols, plastic, refridgerants, etc.

• The chlorine reacts with oxygen atoms in ozone, creating ozone holes (patches that are thinner).

Stratosphere

2nd Layer

• Cold, thin air - few clouds, no storms.

• Lack of weather due to water holding capacity - the air cannot hold water the colder it gets.

• Temperature increases slowly with altitude increase, due to the ozone layer within the upper stratosphere.

Troposphere

1st Layer (Closest to Earth)

• Majority of Earth's atmosphere & where all living things reside.

• The majority of the Earth's weather occurs here.

• As altitude increases, temperature decreases.

Temperature Inversion in the Troposphere

• Atmospheric condition in which warm air traps cooler air, and pollutants that are trapped within this cool air, near the Earth's surface.

• Low air quality.

• Pollutants cannot dissipate b/c they get trapped in the cool layer

• Inhaling the toxins can cause illness - outside work/exercise not recommended in these conditions

• As altitude increases, temperature rises

Changes in Earth's Atmosphere

Earth's climate is not consistent or stable, changed a lot over geologic time due to the complex interactions between abiotic and biotic factors. O2 used to be extremely rare on earth/the atmosphere, organisms evolved photosynthesis thus changing the atmosphere and allowing animals to breathe oxygen-rich air. Also, anything that burns produces carbon dioxide.

The Greenhouse Effect

• The greenhouse effect occurs when greenhouse gases in a planet's atmosphere cause some of the heat radiated from the planet's surface to build up at the planet's surface.Ozone, carbon dioxide, methane, and water vapor are all considered greenhouse gases.

• These substances absorb and trap the sun's radiation, warming the planet.

• Ever increasing amounts of these substances, mainly from burning fossil fuels, is a major existential threat for life on the planet.

Pollution

Gases, liquids, and solids present in high enough concentrations to harm humans, animals, and/or the environment.

Natural sources of air pollution

Wind blown dust, volcanic activity, wildfires, hydrocarbons such as CH4 emitted by plants and animals (natural VOCs)

Anthropogenic sources of air pollution

Stationary sources: industry, agriculture, power generation.

Mobile sources: automobiles, other forms of fossil fuel powered transportation.

Primary vs. Secondary Air Pollution

Primary: Directly enters the atmosphere already in a harmful form (CO, NO2, SO2, Particulates, VOCs).

Secondary: Harmful form created via chemical reactions with other substances in the atmosphere (ground level ozone, nitric acid, sulfuric acid, smog).

What are the 6 criteria pollutants?

1. Sulfur Dioxide (SO2)

2. Nitrogen Oxides (NOx)

3. Carbon Monoxide (CO)

4. Ozone (O3)

5. Particulate Matter

6. Lead

Ground Level Ozone - DEFINITION

Gas composed of 3 oxygen molecules. Created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC)

Ground Level Ozone - COMMON SOURCES

This happens when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources chemically react in the presence of sunlight.

Ground Level Ozone - HARMFUL EFFECTS

Inflame and damage the airways. Make the lungs more susceptible to infection. Can stunt growth of plants, cause disease in certain plants, and affect water and nutrient cycles.

Suspended Particulate Matter (SPM) - DEFINITION

A mixture of solid particles and liquid droplets suspended in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye.

Suspended Particulate Matter (SPM) - COMMON SOURCES

Construction sites, unpaved roads, fields, smokestacks or fires. Most particles form in the atmosphere as a result of complex reactions of chemicals such as sulfur dioxide and nitrogen oxides, which are pollutants emitted from power plants, industries and automobiles.

Suspended Particulate Matter (SPM) - HARMFUL EFFECTS

Particles less than 10 micrometers in diameter can get deep into your lungs and some may even get into your bloodstream. Premature death in people with heart or lung disease. Damaging sensitive forests and farm crops, affecting the diversity of ecosystems, contributing to acid rain effects.

Lead - DEFINITION

Lead is a chemical element on the perodic table and there is only one atom in in(Pb). It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point.

Lead - COMMON SOURCES

National levels: ore/metal processing, aircraft. Other: Waste incinerators, utilities, lead batteries

Lead - HARMFUL EFFECTS

On humans: Accmnalates in the bones and effects “the nervous system, kidney function, immune system, reproductive and developmental systems and the cardiovascular system”. Behaviroal deficits are also common in children who are exposed to lead and this affects IQ, behavior, etc. Environment: decreased growth in plants/animals/neurological effects in vertebrates. Neurotoxin.

Carbon Monoxide - DEFINITION

CO is a colorless and odorless primary pollutant gas that is dangerous when inhaled in big amounts. It is released when something is combusted incompletely.

Carbon Monoxide - COMMON SOURCES

Vehicles or machinery that burn fossil fuels

Carbon Monoxide - HARMFUL EFFECTS

The amount of oxygen that is integrated into the bloodstream is reduced and this is bad because the brain/heart/other organs need the oxygen. If it's inside, CO can cause dizziness, confusion and even death at times. If there are people that already have health conditions related to oxygen intake, this can further exacerbate those conditions.

Sulfur Dioxide - DEFINITION

Gaseous air pollutant composed of sulfur and oxygen

Sulfur Dioxide - COMMON SOURCES

mainly burning fossil fuels from industrial facilities, but also metal extraction, volcanoes, locomotives

Sulfur Dioxide - HARMFUL EFFECTS

human respiratory system is impacted, and SO2 can react to form other sulfur oxides that form particulate matter, damage trees and plants, acid deposition

Nitrogen Oxides - DEFINITION

Nitrogen dioxide is one of a group of highly reactive gases known as nitrogen oxides (NOx).

Nitrogen Oxides - COMMON SOURCES

Burning of fossil fuels, particularly from fuel powered transportation and power plants

Nitrogen Oxides - HARMFUL EFFECTS

Irritates the respiratory system leading to coughing, wheezing, difficulty breathing, forms acid rain by reacting with water, oxygen, other chemicals

Volatile Organic Compounds (VOCs / Hydrocarbons)

Any compound of carbon and hydrogen. Specifically, compounds that have a high vapor pressure and low water solubility, give off toxic fumes, participate in atmospheric chemical reactions. Many VOCs are human-made chemicals that are used and produced in the manufacture of paints, pharmaceuticals, and refrigerants. Primary pollutants.

Methane

One of the most common VOCs. CH4. 25x more potent at trapping heat per molecule than CO2.

VOCs - COMMON SOURCES

Paints and lacquers, paint strippers, cleaning supplies, pesticides, building materials and furnishings, office equipment such as copiers and printers, correction fluids and carbonless copy paper, graphics and craft materials including glues and adhesives, permanent markers, and photographic solutions.

VOCs - HARMFUL EFFECTS

• Health Effects:

  • Eye, nose, and throat irritation; headaches and loss of coordination; nausea; and damage to the liver, kidneys, or central nervous system.

• Environmental Effects:

  • VOCs can indirectly contribute to material damage by the formation of ozone which is a very strong oxidizing agent and can attack materials such as natural and synthetic rubber, textiles and resins, or those used in surface coatings.

Smog

High density, cloudy/blurry air resulting from increasing concentration of atmospheric pollutants

Industrial Smog

• “Gray Air Smog” - unhealthy mix of sulfur dioxide, suspended droplets of sulfuric acid, and a variety suspended solid particles in outside air

  • Rarely a problem in more developed countries - mainly an issue in industrializing countries where old fashioned or unregulated power plants burn fossil fuels, and coal is still typical home fuel

Photochemical Smog

• “Brown Air Smog”

  • Light activated (photochemical) reactions within an airborne mixture of primary and secondary pollutants

  • Found in large cities with warm climates, key culprits are nitric oxide (NO) and VOCs

  • Additionally: O2 + NOx + VOC in the presence of UV creates ground level ozone (O3)

Distinguish between Industrial smog and Photochemical smog

Industrial smog is largely a result of sulfur compounds, and moreso an issue in developing countries that use higher concentrations of coal and have less regulated fossil fuel usage. On the other hand, photochemical smog is a result of photochemical reactions with airborne pollutants, primary and secondary, and is a greater issue in large cities with warm climates.

How would you classify CO2 (Primary vs. Secondary)?

Primary pollutant due to it being lethal if it was the only thing breathed in and the excessive output of it is detrimental

Primary vs. Secondary Pollutants

A primary pollutant is an air pollutant emitted directly from a source (harmful as it is). A secondary pollutant is not directly emitted as such, but forms when other pollutants (primary pollutants) react in the atmosphere.

• PRIMARY POLLUTANT EXAMPLES:

  • CO, CO2, SO2

• SECONDARY POLLUTANT EXAMPLES:

  • Ozone, sulfuric acid, nitric acid

Montreal Protocol

A 1987 international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion, mainly CFCs.

CFCs

Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine that cause ozone depletion.

What did we replace CFCs with when the Montreal Protocol went into effect?

We replaced CFCs with HFCs, which, while not depleting the ozone, are still damaging due to being potent greenhouse gases - “thousands of times more effective than carbon dioxide at trapping heat in our atmosphere”

Successes of the Montreal Protocol

CFC consumption declined from over 800,000 metric tons in the 1980s to an estimated 156 metric tons in 2014. Experts estimate that by 2050, the ozone layer will be back to the state it was in 1980. It also received extremely unified support (esp. in comparison to other climate legislations).

Are CFCs still in the atmosphere? Are we still producing them?

Even if emissions of remaining gases are in small quantities, they last a while in the atmosphere and will continue to build up over time.

Montreal Protocol Loopholes

• While the Montreal Protocol controls the production and consumption of ODs, there are still people out there with old air conditioners, refrigerators, and insulators that will continue to produce CFCs. (CFC banks)

• Montreal Protocol also does not regulate “ODSs used as feedstocks in making new chemicals or produced as co-products in industrial processes”

• Nitrous oxide is now the most significant OD, and global emissions of N2O are accelerating. 

Kigali Amendment

Countries committed to cut the production and consumption of HFCs by more than 80 percent over the next 30 years.

What does the catalytic converter on your car do and how does it work?

Catalytic converters lower the amount of pollutants emitted from car exhaust by creating chemical reactions that change them to less harmful substances, such as water vapor and carbon dioxide. Gases are intook from the engine and blown over the central catalyst, which has a honeycomb structure and is lined with metals that split up unsafe molecules in the gases. These converted gases then travel out the exhaust pipe.

Why are catalytic converters common targets for theft?

Catalytic converters contain quantities of precious metals such as platinum, palladium, and rhodium. There was an uptick of catalytic converter theft during the pandemic due to people not using their cars as frequently, making them easier to steal.