Actress Jessica Alba has agreed to let her young daughters choose her work clothes for one day if she can convince 10,000 fans to join her in a challenge to save the environment.

The Sin City star has signed up as a global ambassador for Earth Hour 2013, which encourages the public to turn off their lights for 60 minutes on 23 March (12) to conserve energy and encourage sustainability.

Alba is hoping to convince 10,000 people to pledge their support to the campaign by switching to using non-toxic eco-friendly products at home.

If she reaches her target, she will allow her daughters Honor and Haven to dress her for one day, while the co-founders of her eco-friendly family brand The Honest Company will do the same.

She says, "Christopher, Sean, Brian and I, founders of The Honest Company, will let our kids dress the whole Honest team, including us, for work for one day if 10,000 people commit to switch to using non-toxic products in their home."

Alba adds, "The choices we all make in our daily lives can have a massive difference, not only to our children, but also to the very planet on which we live. I hope you'll accept the Honest challenge and help us take the mission of Earth Hour, beyond the hour."