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.
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?