Transportation

Use the lowest-octane gas recommended for your car. Only one in ten cars produced since 1982 require high-octane gasoline, and high-octane gasoline releases a higher concentration of toxic compounds into the air than the lowest octane gasoline.

Drive slower. For every mile per hour you drive under sixty-five miles per hour, you improve your car's fuel efficiency by about 2 percent. So, if you're driving fifty-five miles per hour, you increase your car's fuel efficiency by up to 20 percent.

Abandon your car in favor of cleaner transportation - at first just once a week, and later two to three times a week. As you adjust to new modes of transportation, you should be able to reduce the miles you drive by more than 50 percent. But don't stop there if you can reduce miles even further.