Chapter Fifteen: Air Pollution

Sulfur Dioxide

From combustion of coal and oil - respiratory irritant - affects plant tissue - released during volcanic eruptions and forest fires

Nitrogen Oxides

Typically nitrogen oxide or nitrogen dioxide - cars and stationary fossil fuel combustion - forest fires - lightning - microbial activity - these form smog

Carbon Monoxide

Formed during the incomplete combustion of fossil fuels/matter

Carbon Dioxide

Formed during the complete combustion of fossil fuels/matter

Particulate Matter

Solid or liquid particles suspended in air - from the combustion of wood, manure, biomass, coal, oil, and gasoline - road dust, volcanoes, forest fire, dust storms - ranges from 0.01 um to 100 um (any larger than 10 um aren’t regulated by the EPA) - scatters and absorbs sunlight

Photochemical Oxidants

Air pollutants that form as a result of sunlight reacting with nitrogen and sulfur oxides - forms the secondary pollutant ozone

Sulfurous Smog

Contains sulfur dioxide and sulfate - aka industrial smog

Lead and Mercury

Lead naturally occurs in rocks and slightly in oil and coal - lead in gasoline, lead-based plants, etc. - mercury can be found in coal and oil (especially coal) - these lead to biomagnification

Volatile Organic Compounds (VOCs)

Organic compounds that evaporate at atmospheric temperatures - help to form ozone - typically hydrocarbons - found in gas, perfumes, paints, dry-cleaning fluid, lighter fluid, formaldehyde

Primary Pollutants

Polluting compounds that come directly from an emission source like a smokestack, exhaust pipe, or natural emission source - most hydrocarbons, suspended particles, carbon monoxide, nitrogen dioxide, nitrogen monoxide, sulfur dioxide, and many VOCs

Secondary Pollutants

Primary pollutants that have changed in the presence of sunlight, water, oxygen, or other compounds - ex. ozone (smog), acid rain (carbonic, nitric, sulfuric)

Natural Emissions

Volcanoes- Lightning - Forest Fires - Plants

Human Emission Sources

Monitored, regulated, and controlled - on-road vehicles, power plants, industrial processes, waste disposal (incineration and landfills)

Photochemical Smog Formation

Nitrogen oxides and some VOCs in the presence of sunlight form tropospheric ozone (smog) - nitrogen dioxide splits to form nitrogen oxide from sunlight - the extra oxygen combines with diatomic oxygen (in air) to form ozone - at night, ozone destruction occurs where nitrogen monoxide combines and reforms into diatomic oxygen and nitrogen dioxide

Thermal Inversion

Natural process that doesn’t cause smog but makes the smog more concentrated - a warm layer of air covers a layer of cold, dense air - the warm layer (inversion layer) is trapped between the cooler layers - can trap the emissions that accumulate beneath it - causes increased smog concentration

Formation of Acid Deposition

Nitrogen oxides and sulfur dioxides are released into the atmosphere by natural and manmade processes - these create secondary pollutants of nitric and sulfuric acid - these acids break down further into nitrates, sulfates, and hydrogen ions - eventually washed out of the air by precipitation

Effects of Acid Deposition

Decrease in the pH of water - causes decrease in species biodiversity - impacts food sources at different trophic levels - species have developmental and reproductive problems - mobilization of metals where metals that are bonded to organic/inorganic compounds in soil are released into the water

Fluidized Bed Combustion

Coal is burned near calcium carbonate which absorbs the sulfur and becomes calcium sulfate - helps with sulfur pollution

Reducing nitrogen emissions

Reduce burn temperatures in combustion to reduce nitrogen emissions

Catalytic Converters

Controls exhaust from transportation by making less toxic pollutants - transforms hydrocarbons to oxygen, nitrogen, and CO2

Control of Particulate Matter Tactics

• Gravitational settling

• Fabric filters/baghouse filters

• Electrostatic precipitators (electric charge)

• Scrubbers (uses scrubbing liquid to trap matter) - can also remove SO2

Formation of Stratospheric Ozone Equation

3O₂ — UV sunlight —> 2O₃

Destruction of Stratospheric Ozone Equation

Due to solar radiation (UV rays), CFCs and HFCs break and form Chlorine (Cl) atoms which react with ozone molecules to form Chlorine Monoxide (ClO) - then, it remakes molecular O₂ and Chlorine (the reactions continue)

Cl + O₃ — UV —> ClO + O₂

ClO + O —> Cl + O₂

Indoor Air Pollution for Developing Countries

Use wood, manure, plastic, charcoal, and coal for indoor heating and cooking - no exhaust and little ventilation - results in CO2 and particulates - respiratory infections, pneumonia, bronchitis, and cancer

Indoor Air Pollution for Developed Countries

Spend more time indoors - many materials are made from plastics and other petroleum-based products (many VOCs)

Indoor Air Pollutants (types)

• Carbon Monoxide

• Asbestos

• Radon

• VOCs

Carbon Monoxide

From inefficient burning of fossil fuels, wood, etc. - malfunctioning exhaust systems, furnace heating systems, and natural gas heaters - exposure leads to oxygen deprivation in the brain and then death

Asbestos

Long, thin, fibrous silicate material with insulating properties - causes respiratory diseases and lung cancer

Radon

Occurs naturally from the decay of uranium - exists in granite and other rocks and soil - causes lung cancer

Sick Building Syndrome

A buildup of toxic pollutants in airtight spaces - new and renovated buildings have off-gassing of VOCs and hydrocarbons - causes headaches, nausea, throat/eye irritation - caused by faulty/inadequate ventilation, chemical contamination from indoor/outdoor sources, or biological contamination