Pharrell's Happy to play on loop for 13 days for charity

The Oscar nominated track from Despicable Me 2 has already topped the charts in 20 countries, and now Pharrell is using his song for good through a new United Nations initiative.

Starting on Tuesday (18Mar14), Happy will be played non-stop on a dedicated iHeartRadio station online, and will continue until 31 March (14).

Pharrell has been named this year's (14) celebrity brand ambassador for the UN Foundation's International Day of Happiness, urging fans to promote the movement on various social media platforms with the hashtag "#happinessday".

Organisers behind the initiative are aiming to pull in donations to aid UN humanitarian efforts.