More than 100 schools are teaming up to ditch the car on an air pollution awareness day.

More than 44,000 pupils from 18 boroughs are marking World Car Free Day by encouraging parents and carers to walk or cycle to school, ditching their cars.

The awareness day is part of Transport for London (TfL)'s sustainable travel to school programme, STARS, which aims to improve air quality across London.

TfL statistics show one in three car trips made by Londoners could be walked in less than 25 minutes, and that the school run is a major source of the city's air pollution with it raising to its highest between 8am and 9am.

Tompion Platt, Head of Policy and Communications at Living Streets, a charity aiming to inspire people to walk everyday, said: "Making it safer and easier for more families to walk to school is critical to improving air quality around the school gate.

"Creating safe walking routes, introducing walk to school initiatives and closing school streets to traffic during drop off and pick up times are some of the ways we’re helping schools and parents to ditch the car and choose to walk."

As part of the STARS scheme, a number of schools in London have now set up "car-free" zones at the school gates to discourage parents from dropping their children off, and have established more walking buses to help children get to school safely and with respect for the environment.

Will Norman, Walking and Cycling Commissioner, said: "Walking and cycling to school is a great way to get active and tackle London’s toxic air crisis."

The World Care Free Day takes place today (September 22) across London schools.