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18. What is the difference between a primary air pollutant and a secondary air pollutant? Primary air pollutants are emitted directly into the air from sources. They can have effects both directly and as precursors of secondary air pollutants. Secondary air pollutants are chemicals formed through reactions in the atmosphere. 3

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Name and Formula for Primary Air Pollutant How is it Formed?Principal EffectOther Noted Facts 19. Complete the following chart pertaining to primary air pollutants. Sulfur dioxide (SO 2 ) It is a gas that is formed when sulfur is exposed to oxygen at high temperatures during fossil fuel combustion, oil refining, or metal smelting The formation of acid rain and aerosols SO 2 dissolves in cloud droplets and oxidizes to form sulfuric acid (H 2 SO 4 ), which can fall to Earth as acid rain or snow or form sulfate aerosol particles in the atmosphere. 5

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Name and Formula for Primary Air Pollutant How is it Formed?Principal EffectOther Noted Facts 19. Complete the following chart pertaining to primary air pollutants. Nitrogen oxides (NO and NO 2, referred together as NO x ) These highly reactive gases form when oxygen and nitrogen react at high temperatures during combustion or lightning strikes In the atmosphere NOx reacts with (VOCs) and carbon monoxide to produce ground-level ozone. These are eventually oxidized to nitric acid (HNO 3 ). Nitric acid contributes to acid deposition and to aerosol formation. 7

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Name and Formula for Primary Air Pollutant How is it Formed?Principal EffectOther Noted Facts 19. Complete the following chart pertaining to primary air pollutants. Carbon monoxide (CO) CO is an odorless, colorless gas formed by incomplete combustion of carbon in fuel. 9 Low exposures can aggravate cardiac ailments, while high exposures cause central nervous system impairment or death. It also plays a role in the generation of ground-level ozone. CO binds to hemoglobin in red blood cells, reducing their ability to transport and release oxygen throughout the body.

Name and Formula for Primary Air Pollutant How is it Formed?Principal EffectOther Noted Facts 19. Complete the following chart pertaining to primary air pollutants. Volatile organic compounds (VOCs) VOCs are emitted from a very wide range of sources, including fossil fuel combustion, industrial activities, and natural emissions from vegetation and fires. 10 Some anthropogenic VOCs such as benzene are known carcinogens. VOCs are chemical precursors of ground-level ozone and aerosols.

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Secondary air pollutants form when primary pollutants react in the atmosphere. 21. Ground-level ozone (O 3 ) is a pernicious secondary air pollutant, toxic to both humans and vegetation.

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18 22.In addition to gases, the atmosphere contains solid and liquid particles that are suspended in the air. These particles are referred to as aerosols or particulate matter (PM).

19 They are removed when rain or snow carries them out of the atmosphere or when larger particles settle out of suspension due to gravity Size of aerosols. between 0.01 and 10 micrometers in diameter Aerosols are found where? in the lower troposphere How long do they reside here? a few days State the (2) ways by which they are removed.

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Complete the table to distinguish between large aerosol particles and small aerosol particles. Type of Aerosol Particle Size Generated/Produced - Examples Large usually 1 to 10 micrometers in diameter generated when winds blow sea salt, dust, and other debris into the atmosphere Examples: sea salt, dust Small (fine) diameters less than 1 micrometer produced when precursor gases condense in the atmosphere Major components of fine aerosols are sulfate, nitrate, organic carbon, and elemental carbon. Examples: black carbon, soot

High concentrations of aerosols are thought to be a major cause of what? cardiovascular disease and are also suspected to cause cancer