Earth Science

Human Impacts on the Earth Environment

Causes of Air Pollution

Study Tip
In large car-dependent cities, up to 85% of air pollution can come from car emissions.

Fossil Fuels

  • Fossil fuels are burned for automobiles, power plants, and industrial plants. These do not always burn completely, and incomplete chemical reactions will create pollutants.
  • Pollutants include carbon monoxide, nitrogen dioxide, sulfur dioxide, and hydrocarbons.
Study Tip
In large car-dependent cities, up to 85% of air pollution can come from car emissions.

Biomass Burning

  • Burning animal and plants directly can also cause pollution.
  • Biomass is the total amount of living material found in an environment. Biomass is mainly burned through slash-and-burn agriculture. (Biomass is cut down and burned to make room for human farming.)
  • Burning biomass can produce the same pollutants as burning fossil fuels.
  • It worsens greenhouse gases, since the trees that store carbon dioxide are now cut down.
Biomass Burning
A forest that has been slash-and-burned to make new farmland

Evaporation

  • Volatile organic compounds (VOCs) enter the atmosphere through evaporation. The most common one is methane.
  • They come from human-made products such as paint-thinner, cleaning solvents, preservatives, and other liquids.
Concept Check
  • What are some air pollutants?
  • What is slash-and-burn agriculture? Why does it worsen the greenhouse gas effect?
  • What are VOCs? Where do they come from?