Section 1.4

 Air pollution is the addition of harmful materials to Earth’s atmosphere.  global-warming/pollution-overview/ global-warming/pollution-overview/ 

 Air pollution in one place can spread and affect a wide area. Wind is one of the major ways that air pollution can be spread.

 Scientists classify separate types of pollutants as either gases or particles.  Gas pollutants include carbon monoxide, methane, ozone (when present in the troposphere), sulfur oxides, and nitrogen oxides.  PARTICULATES are tiny particles or droplets that are mixed with the air. Examples include smoke, dust, dirt, pollen, and tiny salt particles from the oceans.  Especially near cities, air pollution comes from the burning of FOSSIL FUELS. These often create a thick cloud of smoke and fog that react with the Sun (SMOG).

 Health problems (irritating eyes, nose, throat, and lungs) such as asthma and lung disease.  Particulates can stick to surfaces, damaging plants, buildings, and other outside objects.  Rain clears the air by removing particles and some gas pollutants from the air. However, some are still harmful when rain moves them from the air to the ground (runoff into the ground, lakes, oceans, etc.).

 The CLEAN AIR ACT limits the amount of pollution that factories and power plants are allowed to release.  The EPA (Environmental Protection Agency) measures air pollution and works to enforce the laws passed by Congress.

 Greenhouse gases are important in that they help keep the Earth a comfortable temperature for living things. However, when too many greenhouse gases are released into the atmosphere, global temperatures may rise too quickly.

 What can you do to reduce greenhouse gases?

 In the 70s, scientists found that certain chemicals were breaking apart ozone molecules (Cl was breaking apart O3 into O2). CFCs put Cl into the atmosphere.  The amount of ozone over Antarctica decreased by half from the 70s to mid 90s.  Since 1987, more than 180 nations have signed an agreement called the Montreal Protocol to stop making chemicals that harm the ozone layer. This may help the ozone level go back to normal in about 50 years.