Environmental Science: Air Pollution and Its Effects

Sources of Air Pollution

• Air pollution is the release of damaging materials into the atmosphere.
• Emissions are substances released into the atmosphere, such as particulate matter (smoke, soot) and gases (sulfur dioxide, carbon monoxide).

Natural Sources of Air Pollution

• Examples: dust storms caused by winds sweeping over dry land, particles and gases released by volcanic eruptions, and smoke, soot, and gases produced by forest and grassland fires.
• Human activities can make some natural pollution worse, such as farming and grazing practices that strip plants from the soil, leading to wind erosion and dust storms.

Human Sources of Air Pollution

• Examples: industry, automobiles, and electricity production.
• Human activities can come from point sources or nonpoint sources, such as millions of cars and trucks together making up a moving nonpoint source.
• Most air pollution comes directly from the combustion of fossil fuels, which release enormous amounts of pollutants into the air.

Primary and Secondary Air Pollutants

• Primary air pollutants are pollutants released directly into the troposphere, which can cause damage themselves or react with other products to cause damage.
• Secondary air pollutants are harmful products produced when primary air pollutants react chemically with other substances.

How Air Pollutants Affect Your Health

• Respiratory system problems: air pollutants irritate people's air passages, causing conditions such as asthma, bronchitis, and emphysema.
• The effect of carbon monoxide: inhaled oxygen binds to hemoglobin, but if there's CO in the air, it binds to the hemoglobin and replaces some of the oxygen, interfering with the body's ability to deliver oxygen to cells, causing headaches, tiredness, nausea, or even death in high concentrations.
• Cancer: soot can cause cancer if inhaled frequently, and benzene, a volatile organic compound (VOC) in gasoline, has been linked to cancer.

Smog and Temperature Inversions

• Smog: an unhealthy mixture of air pollutants that may form over cities and nearby areas, which is a mixture of "smoke" and "fog".
• Industrial smog: smog produced when soot combines with sulfur compounds and water droplets in air.
• Photochemical smog: a thick, brownish haze that forms when sunlight acts on certain air pollutants, such as nitrogen oxides and hydrocarbons.
• Temperature inversions: a condition in the troposphere in which a cooler layer of air is located beneath a layer of warmer air, which prevents pollutants from being dispersed away from the surface.