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

Types of Air Pollutants

Primary Pollutants

• pollutants release directly from the source into the atmosphere, and are hazardous or harmful in its original state

• particulate matter (PM)

  • 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)

  • 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)

  • 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)

  • 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

  • nitrogen oxide (NO)

    • naturally present in the atmosphere- lightning, released during bacterial decomposition (recall: nitrogen cycle)

  • nitrogen dioxide (NO2)

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

    • it is toxic and if sharp unpleasant odor

  • 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

  • smog

    • industrial 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

      • 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

    • why does smog affect some cities but not others?

      • weather conditions

        • higher humidity - more moisture, more suspension of particles

        • wind - disperses air pollutants horizontally; strongest in urban areas with calm winds

        • sunny - more energy from the sun to breakdown molecules that contribute to smog formation

      • topography

        • mountains and valleys - more susceptible to the accumulation of pollutants; blocking effect of mountains and valleys surrounding the town

      • temperature inversion

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

Layers of the Atmosphere

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

• 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

• 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

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Layers of the Atmosphere (Mnemonics) T - Taylor S - Swift M - Mother T - To E - Everyone

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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

• Philippine Clean Air Act

  • seeks to address the growing problem of air pollution in the Philippines

  • prohibits vehicular and industrial sources from emitting pollutants in amounts that can cause significant deterioration of air quality