Atmosphere

Air Pollutant

any substance released through atmospheric activities into the atmosphere, at a concentration sufficient to cause harm to humans, other animals, vegetation or to other materials

Primary Pollutants

type of air pollutant that release directly from the source into the atmosphere, and are hazardous or harmful in its original state

Particulate Matter (PM)

• type of primary pollutant

• inhalants particles (solid or liquid)

• generally defined by the diameter (PM 2.5 - PM 10)

• natural sources

  • smoke from forrest fires, volcanic ash, dust, sea salt spray, pollen grains, bacteria, fungal sponges

• anthropogenic sources

  • combustion of fuels in power generation, emissions from automobiles, dust from mining, agricultural activities, solid-waste burning, microplastics

• health risks

  • penetrates the lungs and enters the bloodstream causing cardiovascular, cerebrovascular, and respiratory impacts

  • in 2013’ it was classified as a cause of lung cancer by WHO’s International Agency for Research on Cancer

Carbon Monoxide (CO)

• type of primary pollutant

• colorless, odorless, gas produced by the incomplete combustion of carbonaceous fuels (ex: wood, petroleum coal, natural gas, kerosene)

• gasoline: hydrocarbons → combustion with oxygen = carbon dioxide and water

• limited supply of oxygen → not complete combustion = carbon monoxide

• dominant source: motor vehicles

• modern catalytic converters:

  • can convert nitrogen oxides to nitrogen gas and oxygen gas and carbon monoxide to carbon dioxide

• health risks

  • can be extremely hazardous when inhaled at high concentrations

  • colorless, tasteless, and colorless difficult to detect

  • exposure to moderate concentrations (as low as 10 ppm) for extended periods of time: may be detrimental to one’s health and even death

  • symptoms of carbon monoxide poisoning: dizziness, drowsiness, slow reflexes, respiratory failure, impaired judgment, loss of consciousness

Sulfur Dioxide (SO2)

• type of primary pollutant

• colorless gas that is readily soluble in water

• where further oxidized = sulfur trioxide (SO3)

  • when reacted with water → forms secondary pollutant sulfuric acid (H2SO4)—-major component of acid rain

• natural sources

  • decomposition of sulfur-containing organic matter, volcanic eruptions

• anthropogenic sources

  • combustion of fossil fuels for domestic heating, industries and power generation

• health risks:

  • exposure results in irritation of eyes and respiratory passages

  • also harmful to plants and vegetation

Volatile Organic Compounds (VOC)

• type of primary pollutant

• compounds that easily become vapors and may contain hydrocarbons

• most of these compounds are not toxic by themselves but are contributors to the formation of secondary pollutants

• often components of petroleum fuels, hydraulic fluids, paint thinners, and dry cleaning agents

• natural sources

  • pine, eucalyptus, sandalwood trees

• anthropogenic sources

  • inefficient combustion of fossil fuels in engines, leaks in gas pumps and storage tanks (e.g., jeepneys, buses, tricycles)

    • tricycles: burn fuel at a lower efficiency

Nitrogen Oxides (NO2)

• naturally present in the atmosphere- lightning, released during bacterial decomposition

• natural sources

  • lightning, decomposition

• ambient sources

  • high temperature combustion of fuels (e.g., heating, transportation, industry, and power generation)

• household sources

  • equipment that burn fuels such as furnaces, fireplaces, gas stoves, and ovens

• health risks

  • nitrogen dioxide causes irritation of the eyes, inflammation of lung tissues and emphysema

  • plays in the formation of secondary pollutants that contribute to the formation of photochemical smog

Nitrogen Dioxide (NO2)

• reddish-brown gas that is soluble in water, and a strong oxidant

• it is toxic and if sharp unpleasant odor

Industrial Smog

• type of primary pollutant and smog

• mixture of fly ash, soot, sulfur dioxide and variety of VOCs that are formed especially in burning of coal

• type of smog usually forms over areas with a high density of vehicles or industrial processes

Photochemical Smog

• type of primary pollutant and smog

• result of series of reactions that occur in the presence of high concentration of nitrogen oxides, volatile organic compounds and initiated by the sunlight

• main contributors: VOCs, nitrogen oxides, sunlight, water

Secondary Pollutants

• released in a form not immediately harmful but are converted in the atmosphere through chemical reactions into harmful and hazardous forms

Atmosphere

• composed of layers of gases held close to the earth by pull of gravity

• protects living organisms from the sun’s harmful UV rays

• moderates earth’s climate

• provides carbon dioxide and oxygen to organisms

Troposphere

• lowest layer of earth’s atmosphere

• extends from the earth’s surface up to an average altitude of about 12 km

• later where weather occurs, and it is where we live and breathe

• 78% nitrogen, 21% oxygen, 0.9% argon, 0.4% carbon dioxide, 0.01% other gases

Stratosphere

• above the troposphere

• extends roughly from an altitude of about 12-50 km above the earth’s surface

• where ozone layer is

• ozone molecules in this layer absorb high-energy UV light from the sun

• lacks turbulence so commercial passenger planes fly in the lower stratosphere

Mesosphere

• above the stratosphere

• extends approximately from an altitude of about 50-85 km above the earth’s surface

• where meteors burn

• air is far too thin to breathe

Thermosphere

• above the mesosphere

• begins approximately at an altitude of 85 km and has no clearly defined upper boundary

• high energy x-rays and UV radiation from the sun are absorbed here

  • houses the Karman line—- approximate boundary of atmosphere and outer space

Exosphere

• uppermost region of the atmosphere and gradually transitions into the vacuum of space

• final frontier of the earth’s gaseous envelop

• where satellites and other human-made objects in earth’s orbit are found

• very very very very thin air

Greenhouse Effect

• when heat remains trapped in the atmosphere, caused by the build-up of greenhouse gases

  • water vapor

  • carbon dioxide

  • methane

• absorb heat which is radiated from the earth. they then release this energy, which in turn keeps the earth warm

• impact of humans

  • rice farming in paddy fields releases methane

  • the burning of fossil fuels in vehicles and power stations releases carbon dioxide

  • deforestation releases carbon dioxide and cutting down trees also reduces the removal of carbon dioxide through photosynthesis

  • cattle farming releases methane