That Australia is on the verge of a near-national ban on thin, single-use plastic shopping bags owes much to the tenacity of campaigners such as Rebecca Prince-Ruiz and Jon Dee.

Dismayed by a month's amount of garbage churned out by one suburb, Ms Prince-Ruiz, an adult educator in local government, decided to tap several workmates to launch Plastic Free July in 2011.

Rebecca Prince-Ruiz, founder of Perth-based Plastics Free July, an organisation signing people from around the world.

From 40 participants in year one, the campaign to cut single-use plastics had swollen to 2 million - half in Australia - in 159 nations last year. Another half million are expected to join this month's effort.

The founder attributes the success to people realising "small daily steps" can add up to significant outcomes. "We're about what people can do - we focus on the positive and the solutions".