(CNN) -- To offset carbon dioxide, a Japanese airline is asking its passengers to go to the toilet before boarding.
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.
Flights will also show educational films on the environment.
The month-long trial program, which began October 1, will be evaluated and may be extended if successful, Tezuka said.
In true Japanese fashion, the encouragement to eliminate is more suggested than explicit. This is what is announced before boarding the flights: "This flight is a so-called 'eFlight.' The idea behind the operation is to think about the Earth in the sky above. Fuel reduction by lightening the weight of the aircraft will lead to restrain the carbon dioxide emission, which is one of the causes of global warming. Thank you for your understanding."
So no mother-like admonishments to use the toilet before leaving? "No, it's more subtle than that," Tezuka said. People are also encouraged to pack lighter for the flights, although no additional weight restrictions apply.
The program comes as the airline industry in Japan is struggling. The nation's largest carrier, Japan Airlines, is seeking a government bailout and forecasts $700 million in losses this year. This week, ANA's stock price hit a 52-week low in trading Wednesday.