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I know it is terrible for the environment and also a serious health threat, so I hesitate to use pencils. But plastic pens seem like a bad idea, too. What should I stock up on before heading back to college?

By Tobin Hack

Should I drive my daughter the 5.5 miles to her school in my 2006 Toyota Prius, or have her take the school bus?
—Meredith, CO

Calculations are cold, unfeeling things, and subject to lots of outside factors: Is your daughter’s school on the way to your job, or would you turn around and drive right back home? Would you take the neighbors’ kid along as well? What model is the bus, and would it be full to capacity? Would it retrace its route to a garage between the morning pickups and afternoon dropoffs, or wait near the school?

But let’s do some rough estimating. If there are 180 school days in the year, you’re driving 5.5 miles four times a day (twice in the morning, twice in the afternoon), 180 times. That’s 3,960 miles total. According to, a nonprofit online carbon calculator, driving 4,000 miles in your Toyota Prius will produce about 0.65 tons of CO2.

Now let’s talk about the bus scenario. Matthew Solomon, Mobile Source Analyst for nonprofit Northeast States for Coordinated Air Use Management (NESCAUM), estimates that the average school bus (carrying 72 students and getting about 7 miles to the gallon) would emit 0.089 tons of CO2 per passenger over the course of 4,000 miles. So no matter how you slice it, the bus is far and away your greenest option. Plus, putting your daughter on the bus at an early age will teach her to support public transportation—especially if you take the time to explain your logic to her.

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Issue 25

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