Take public transportation or carpool
Buses, trains, airplanes — they all produce a certain amount of pollution. But like all forms of mass transportation, the amount of pollution produced is distributed among a large number of passengers, so they produce less pollution per person than a car with a single person in it does. Taking public transportation when you travel (and especially on your daily commute) is an important way of reducing transportation pollution. What if public transportation doesn't go where you need it to go and the only way you can get there is by car? Then get in a car with other people. Join a car pool and go to work with friends and coworkers. Not only will this produce less pollution per person, but it will also let you use the high-speed carpool lanes on the freeway.