One of the region's bus operators claims congestion is slowing journeys and thereby reducing frequency, putting people off buses and into even more cars.
Trentbarton, which operates in Derbyshire, Leicestershire and Nottinghamshire, is calling on councils to give buses priority to improve services and tackle air pollution.
The cities are already both in the top 10 for illegal levels of nitrogen dioxide.
The local authorities say they're working together to invest in better bus routes.
A Leicester school will be taking its classroom activities out onto a traffic-free street as part of national Clean Air Day.
The road outside Catherine Junior School will be closed until 17:00 to allow pupils enjoy classes and other activities outdoors.
Pupils, parents and school staff will be encouraged to walk, cycle, scoot or skate to school and leave the car at home.
Pupils at a school in Cannock will be asking drivers and parents to turn off their engines when parked.
High vis jackets and little traffic warden outfits will be given to children at Heath Hayes Primary School when they head out onto the streets.
They'll be walk for 5 minutes in different directions from the school to see how far they get and use the information to create a map to show parents where they could park.
They're also checking trees for lichen as this is a good indicator of air quality.
Food ordering app Deliveroo is handing out air quality masks to its delivery riders in Birmingham.
More than half of the app’s 25,000 UK riders use bicycles to make deliveries.
The company will make them available to the cycling general public later in the summer.
Anyone in the West Midlands can travel free today on National Express buses if they purchase a 'daysaver' ticket via the operator's app.
The ticket can be used for unlimited travel on any National Express West Midlands or National Express Coventry service.
It would usually cost £4.60.