When commuters sign up to take part in our financial incentives, we're rewarding their decision to try alternatives that help reduce traffic congestion and air pollution. But another significant benefit to us is the information generated by each participant that helps us track clean commute activity. This information is represented in terms of: reduction in vehicle miles of travel, reduction in air pollution and savings on commute costs.

Since the first commuters began logging their daily activity in 2002 as part of the Commuter Rewards program, here's what we know:

• 75,000 commuters have taken part in our programs, logging more than 10 million clean commute trips and saving $100 million on commute costs

• Each day, these efforts mean 1.2 million fewer vehicle miles of travel on Georgia roads -- enough miles to circle the Earth 48 times

• The impact of this reduction in mileage means 600 tons of pollution are kept out of the air we breathe each day -- the equivalent weight of a dozen fully-loaded 18-wheelers.

From this vantage point, it's clear that the combined efforts of legions of commuters are making a difference in air quality. But what difference can individual commuters make? When sustained over a long period of time, there are many individual commuters we've identified whose long-term efforts have kept tens of thousands of pounds of pollution out of the air we breathe. These people have been faithfully logging their clean commute activity online for years -- long after their initial financial incentives that brought them to The Clean Air Campaign have run dry.

The Clean Air Campaign and its partners have created a new program that celebrates these individuals and their dedication over the years. The Clean Air Commuter Champion program recognizes the commuters who have reached specific milestones in pollution reduction because of their dedication to use alternatives to driving alone.

In our first wave of recognition, 900 Clean Air Commuter Champions are receiving a certificate announcing their achievement for eliminating 25,000 pounds of air pollution, a special gift and coveted bragging rights that their efforts are making a difference. And because this is centered around travel to and from work, employers will also receive a letter from The Clean Air Campaign applauding the "green" efforts of their champion employees who found a better way to work.

Each of us has heard the familiar refrain, "lead by example." When you meet a Clean Air Commuter Champion who has been leading by example for a long time, be sure to give that person your heartfelt thanks and a pat on the back.

Happy Earth Day. Are you thinking"green?" ... are you acting "green?" ... or does the thought of tackling some of the abstract environmental problems out there make your brain hurt? Most people say they aspire to live "green" and certainly the Earth Day theme has proven that it can extend beyond just one day.

But many of us admit that we don't see how our individual efforts can help move the needle on reducing pollution or beating back global warming. The obvious issue is that phrases like "the environment" and "greenhouse gases" and "pollution" are amorphous. Each of these problems has different context for each of us. Likewise, the solution to these problems -- "going green" -- means different things to different people. So it's up to each of us as individuals to define the word "green" and decide how we fit it into our respective values and lifestyles. For some, it's pledging to take part in the One Ton Challenge to tackle air quality problems that result from too many cars on the road. For others, it's remembering to shut off idling engines on school grounds.

What does "going green" mean to you? The Clean Air Campaign asked that question of some commuters, employers, schools and community figures. Over the course of the next few weeks, we'll examine in this space what the phrase means and how we translate our individual definition of "green" into action.