carbon footprint
One way to measure how much carbon dioxide you contribute to the atmosphere is by calculating your carbon footprint. There are a lot of variables to consider including the gas mileage of your family's car and how your local power plant generates its electricity. You can use this handy carbon footprint calculator software to help figure out your carbon footprint.
A lot of the same activities that produce carbon dioxide also cause air pollution, so by lowering your carbon footprint you can help the environment in many ways.