the “big five” air pollutants
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The “Big Five” Air Pollutants. Carbon Monoxide. When fossil fuels and other organic fuels (e.g. wood) burn, they release water vapor and carbon dioxide by a process called “complete combustion” - PowerPoint PPT PresentationTRANSCRIPT
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The “Big Five” Air Pollutants
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Carbon Monoxide
• When fossil fuels and other organic fuels (e.g. wood) burn, they release water vapor and carbon dioxide by a process called “complete combustion”
• This reaction is never truly perfect, however, and as a result, we get a fair amount of “incomplete combustion”
• Incomplete combustion is the source of several waste products that come from burning fossil fuels
• One product of incomplete combustion is carbon monoxide, a very deadly poison
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Carbon Monoxide
• Carbon monoxide binds to hemoglobin which would normally carry oxygen to the body’s organs, but instead carry carbon monoxide
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Carbon Monoxide
Carbon Monoxide Oxygen
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Carbon Monoxide
• Sources of carbon monoxide include:– Automobile exhaust– Furnaces– Cigarettes– Fires
• Indoor carbon monoxide detectors can be installed to protect residents of the house from over-exposure
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Carbon Monoxide• We can minimize (but not
eliminate) the amount of carbon monoxide released by a car using a catalytic converter
• Catalytic converters cause carbon monoxide (and other waste products) to react and form less harmful substances
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Unburned Hydrocarbons
• Also called volatile organic compounds (VOC’s)• Sources– Incomplete combustion of gasoline– Evaporation of gasoline or other solvents (paints,
cleaning fluids, etc)• Are partly dealt with by catalytic converters
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Nitrogen Oxides
• Referred to as Nox as it can be several compounds of nitrogen and oxygen (NO2, N2O4, for example)
• Sources– Incomplete combustion in car engines– Incomplete combustion in furnaces
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VOC and NOx
• When VOC’s and NOx’s are combined together in the atmosphere, and exposed to sunlight, the combination produces photochemical smog
• Smog contains three components– VOC’s– NOx’s– Ozone
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VOC and NOx
• Ozone is found in two places:– Stratosphere –
protects sun from ultraviolet radiation
– Troposphere – acts as key component of smog
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VOC and NOx
• VOC’s & Nox undergo a chemical reaction in the sun to produce ozone
• Ozone in the troposphere– Lung irritant– Eye irritant– Been shown to cause emphysema
• NOx
– Brown color of smog– Shown to cause numerous breathing disorders, including
lung cancer
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VOC and NOx
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Sulfur Oxides (SOx)
• Coal contains sulfur (though the higher quality coals, anthracite, have a very low sulfur content).
• When coal burns, this sulfur becomes a sulfur oxide (SOx) released into the air. Sox react with water in the air to become very acidic, forming acid rain
• Can be controlled by scrubbing, a process used to remove sulfur from emissions where coal is burned
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Sulfur Oxides (SOx)
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Particulates
• Particulates – small solid particles or liquid droplets suspended in air currents
• Most are natural (pollen, fog for example)• Many arise from industrial and combustion
processes• Particulates reduce visibility, cause stains, and
may play a role in climate change