Sock It to Them!


Science and Social Studies


1 Class period


  • Marker
  • Masking tape
  • New white tube socks
  • Oven mitts or heavy gloves
  • Pen
  • Rubber bands
  • A variety of motor vehicles (cars, trucks, buses)


The students will do the following:

  • Describe some different sources of air pollution, and some of the effects of air pollution
  • Describe air pollution from motor vehicles
  • Understand the role of the Environmental Protection Agency in the federal vehicle control programs and what has been accomplished under these programs


In 1986 there were almost 500 million vehicles operating worldwide. If the present growth rate continues, by the year 2030 there will be one billion vehicles world-wide. As the number of vehicles on the road increases, so does the atmospheric pollution. Presently more than half of the air pollution in North America is the direct result of mobile sources, such as cars, planes, trains, and boats. Emissions from motor vehicles contribute to five of the six criteria air pollutants: lead, carbon monoxide, nitrogen oxides, ozone and airborne particulate matter.

Motor vehicles are the main source of carbon monoxide, an invisible, odorless gas resulting from the incomplete combustion of fuel. Inefficient burning of gasoline usually occurs when vehicles are started in the morning, idled, or moving slowly in heavy or congested traffic. Nitrogen dioxide, a reddish-brown toxic gas, is also produced by combustion sources, such as vehicles. Ozone, a major component of smog, is produced when sunlight triggers a chemical reaction between naturally occurring atmospheric gases and pollutants such as nitrogen oxide and hydrocarbons. Diesel engines are considered a major source of particulate matter pollution.

The Environmental Protection Agency (EPA) is working to reduce the amount of vehicle emissions by setting vehicle emission control programs. State and local governments have implemented other important control programs, such as E-checks. New technologies to reduce motor vehicle pollution are actively being developed, as are a new breed of car, such as the new gasoline/electric hybrids, the Honda Insight and Toyota Prius. Many vehicles are being designed to have greater fuel economy, more efficient burning of gasoline, and to reduce wind drag.


Setting the Stage

  1. Ask the students to identify sources of air pollution in the community. Included in this list should be automobiles, factories, power plants, farming, gas stations, wood or oil-burning stoves, and natural sources.
  2. Explain to the students what happens when a car burns gasoline or diesel. Some of the fuel is changed into energy to move the vehicle. By products of the process include heat and air pollutants which exist through the exhaust system.
  3. Use the background information to discuss with your students the pollutants that are emitted through the exhaust.


  1. Have students assemble in the parking lot around pre-elected vehicles (choose vehicles that use a variety of fuels) for a demonstration to test exhausts. Old and new vehicles can also provide variation.
  2. Cautions: The experiment should never be conducted in a closed building. Emergency brake should be set on each vehicle. Use oven mitts or gloves when putting socks on and taking them off the vehicles. Students should stand away from the vehicles during the test. Do not touch tailpipe until car has cooled for five minutes.
  3. Make a label for each sock with the following information: model, make, engine type, and model year.
  4. Place a white tube sock over each tailpipe and then start the engines. Caution: Make sure the students stand away from the vehicles. Note: The elastic sock should fit snugly over the tailpipe. If not, secure with a rubber band.
  5. After approximately 5 minutes, turn the engines off. Use extreme caution as the tail pipe will be very hot, and remove the sock using your oven mitts. Turn the sock inside out and attach the label.
  6. Arrange the sock from cleanest to dirtiest. Discuss the results with your students, asking which caused the most/least noticeable pollution. Ask if the socks were dry or damp. Note: Remind students that they are only seeing particulate matter (dust, soot etc.) and not any of the harmful gases such as Sulfur Oxides, or carbon monoxide.


Have students use the information to make posters of the most heavily polluting models by year or model. Discuss alternative transportation and how alternatives to individual cars can be made to work (mass transit, biking, and walking can also be discussed).

Lesson Information

This lesson is from the Air Quality Resource Guide, Grades K-12, developed by the Kentucky Division for Air Quality and Air and Waste Management, in cooperation with the EPA.