To offset carbon dioxide, a Japanese airline is asking its passengers to go to the toilet before boarding.

(CNN) -- To offset carbon dioxide, a Japanese airline is asking its passengers to go to the toilet before boarding.

All Nippon Airways is asking passengers to use the restroom before flying to reduce weight.

The unusual request by All Nippon Airways (ANA) is part of its "e-Flight" promotional program to reduce the amount of carbon expelled on 38 domestic routes and its twice daily international flights to Singapore.

"Asking passengers to go to the toilet (before boarding) is just a small part of the program," said spokeswoman Megumi Tezuka, which includes using recycled paper cups and plastic bottles instead of glass.

"We are making these items lighter -- and making the passengers lighter, a little bit," Tezuka said.

The airline estimates that if 50 percent of passengers relieved themselves before boarding, it would reduce carbon dioxide by 4.2 tons a month.

How To Reduce Your Carbon Footprint

Your carbon footprint is how many greenhouse gases you release in your daily activities. Be remembered by your good deeds, not your carbon emissions.

How To Reduce Your Carbon Footprint on Howcast

Step 1: Turn thermostat up/down
Turn your thermostat up in the summer or down in the winter by just two degrees, and you’ll prevent hundreds of pounds of carbon dioxide from being released each year.

Close doors to rooms that you are not using to maximize heating and air conditioning. Insulate windows and doors to save even more heating costs.

Step 2: Unplug electronics
Turn off and unplug your computer, TV, and other electronics when you’re not using them. Even electronics in sleep mode draw power.

Leaving your TV cable box on 24 hours a day uses about 65% as much energy as a standard refrigerator.

Step 3: Change bulbs
Change all the incandescent bulbs in your home to compact fluorescent bulbs, which use about 75% less energy.

Step 4: Do full loads of laundry/dishwashing
Do your laundry or run a dishwasher only when you have a full load. It saves water and it’s an excuse not to clean.

Step 5: Eat local
Eat local: An organic out-of-season vegetable from the other side of the world may sound delicious, but it had to make that trip on a huge container ship.

Take a canvas tote with you shopping, so you have a ready – and better – answer to the question “paper or plastic?”

Step 6: Bring own coffee cup/mug
Bring your own cup or mug when you buy coffee and stop tossing an average of 20 pounds of disposable cups a year.

Step 7: Cut back on bottled water
Cut back on bottled water. Most tap water is perfectly safe to drink, and making the plastic and transporting the bottles uses huge quantities of fossil fuels.

Step 8: Plant a tree
Plant a tree. Trees help reduce greenhouse gases, and every one counts. Consider it a peace offering to the Earth.

Step 9: Consolidate car trips
Don’t jump in your car every time you feel the urge to run an errand. Plan and consolidate your trips to cut down on gas.

Step 10: Carpool, public transportation, bike, or walk
When you can, carpool, use public transportation, or ride your bicycle. Or walk, proud to be treading lightly.

Cattle produce as much as 37% of the atmosphere’s methane, a greenhouse gas 20 times more potent than carbon dioxide.