Japanese airline All Nippon Airways (ANA) is determined to lower its carbon emissions any way possible, and that includes an experimental new policy: pee before you fly.

And they’re not just putting up a sign requesting compliance. The airline has ‘loo attendants’ standing at the gates that ask passengers if they need to use the restroom before boarding.

Officials say empty bladders will reduce passengers’ overall weight, therefore saving and reducing carbon emissions. The policy could lead to a five-ton reduction in emissions per month, ANA officials say, and that will save the company money as well.

The policy went into effect on Oct. 1 and will remain in place for four weeks so ANA can evaluate its effectiveness. The trial will be expanded if it’s received well by passengers.

Though it may be the strangest yet, this policy is just one of many that airlines are implementing in an effort to control greenhouse gas emissions.

The international airline industry, which is the fastest-growing source of carbon emissions, recently agreed to slash its emissions to half their 2005 levels by 2050 using a combination of policy changes and new technology.