LBC presenter, Nick Ferrari, clashed with the Green party's Greater London Assembly member, Caroline Russel, after the radio host suggested that the city's cycle lanes were contributing to London's poor air quality.
The presenter made the point after the councillor told him that, cars were "chugging out exhaust fumes", and that more vehicles should be taken off the road.
She went on to argue with Ferrari saying: "If we want to be able to trust the air we breathe, we have to start travelling differently in our city.
"And what car free day is all about is showing people how different our city streets can be and that using a car is not inevitable for everyone and we need to imagine how much better our city will be without that pollution and road danger."
The debate over the capital's degrading air quality comes as London mayor, Sadiq Khan, announced plans to close more roads to create a car-free day to tackle pollution.