A list of the most common air pollutants – sources and effects Criteria Pollutants A list of the most common air pollutants – sources and effects

Carbon Monoxide - CO Produced by incomplete combustion Main source - transportation Unvented kerosene and gas space heaters; leaking chimneys and furnaces; back-drafting from furnaces, gas water heaters, wood stoves, and fireplaces; gas stoves; generators and other gasoline powered equipment; automobile exhaust from attached garages; and tobacco smoke.

Nitrogen Oxides - NOx About 50% from transportation, about 50% from industry Reaction of nitrogen and oxygen in high temperature combustion processes Precursor to photochemical SMOG Form nitric acid HNO3 - about 1/3 acid rain Contribute to ozone depletion in the stratosphere

Sulfur Dioxide – SO2 ~2/3 from coal burning power plants Precursor to acid rain – H2SO4

Hydrocarbons (HC) and Volatile Organic Compounds (VOC) Industrial solvents, transportation Natural sources – plants Cars - catalytic converters Lead to photochemical SMOG Effects are long term including adverse neurological, reproductive and developmental effects as well as having associations with cancer.

Ozone – O3 Byproduct of transportation Component of photochemical SMOG Pollutant in the troposphere Good in the stratosphere (UV ray protection!) Exposure to elevated levels (on the ground) can lead to severe coughing, shortness of breath, pain on breathing, lung and eye irritation and greater susceptibility to respiratory diseases.

Photochemical Smog

Smog: For the Non Chemist Photochemical smog is brown smog, the gray-brown haze that fills the air in many cities. To form photochemical smog, three main ingredients are needed: nitrogen oxides (NOx), hydrocarbons, and energy from the sun in the form of ultraviolet light (UV). The first thing that starts the chain of events is that people start driving in the morning.  As gasoline is burned, nitrogen (N2) in the atmosphere is also burned, or oxidized, forming nitric oxide (NO) N2 + O2 =2NO

Smog: Non-Chem. Continued Hydrocarbons and carbon monoxide (CO) will also be emitted by cars.   Hydrocarbons are volatile organic compounds. In the air, nitric oxide combines with molecular oxygen to form nitrogen dioxide within a few hours. 2NO +  O2--------->2NO2 Nitrogen dioxide absorbs light energy and splits to form nitric oxide and atomic oxygen: NO2-->NO + O Then, in sunlight, the atomic oxygen combines with oxygen gas to form ozone (O3): O+ O2--->O3

Components of Photochemical Smog In bright sunlight: Nitrogen oxides, Hydrocarbons, and Oxygen interact chemically to produce powerful oxidants like ozone (O3) These secondary pollutants are damaging to plant life and lead to the formation of photochemical smog.

Ozone Formation Formulas

Suspended Particulate Matter - SPM Majority from industry Fugitive - SPM not from a smokestack or tailpipe- dust , sand, etc. Aerosols < 1 micrometer in diameter - most not caught by filters

The Great Smog of 1952 London was covered in low level smog for five full days in 1952. Over 4,000 people died, and thousands more hospitalized due to the poor air quality. The death rate peaked at 900 people per day Mortality due to pneumonia and bronchitis increased sevenfold during this short time.

Days of Toxic Darkness Huge quantities of impurities were released during the period on question. 1000 tons of smoke particles 2,000 tons of carbon dioxide 140 tons of hydrochloric acid 14 tons of fluorine. 370 tonnes of sulphur dioxide were converted to 800 tonnes of sulphuric acid

Not the first time… London also suffered the same air quality problems in 1813, 1873, 1882, 1891, 1892, and 1948. Air quality has been a concern in London since the early 13th century. Early industrial developments lead to massive quantities of particulate matter. Causing eye and lung irritation, and death due to poisonous inhalation. All were potentially condensation nuclei, the tiny solid particles on which condensation forms. From the gases, corrosive acids were formed, notably sulphuric acid, which is produced when sulphur dioxide combines with oxygen and water. Even with new air quality measures in place (the Clean Air Act of 1956), London suffered another toxic fog in 1991.

Pollution Credits? (Or Emissions Trading) The United States began emissions trading after passage of the 1990 Clean Air Act, which authorized the Environmental Protection Agency to put a cap on how much sulfur dioxide (which causes acid rain) a fossil-fueled plant was allowed to emit. The state or central government would set an industry-wide "cap" on carbon dioxide emissions, lower than the current amount, and then give each power plant a target and a deadline. Companies that reduce emissions further than required could then "trade" emission credits with companies who cannot meet their goals.

Effect of Pollution Credits on the Environment The main effect is to control a pollutant in a socially-controlled way ensuring that the effects of humans on the environment are controlled, rather than accidental. An important secondary effect is to disperse pollution sources. This occurs because the operators of polluting enterprises will naturally sell as many licenses as they can afford to. This is good, because at any given location, concentrations of a pollutant will be significantly less. A final effect is that if the total permitted amounts are fixed or decreasing, public interest groups can decrease them further by purchasing licenses. The net effect is to drive total emissions toward zero with no economic harm to industry.