A lack of social distancing on school buses is contradicting coronavirus bubbles in place in the classroom, a parent has said.
Gary Langdon said his 14-year-old son, Iestyn, spends an hour each day on a 20-seat minibus with 15 other children, 14 of whom are in different classes.
But once at school in Neath Port Talbot, different classes cannot mix.
Neath Port Talbot council said there was no requirement to maintain contact groups on school transport.
'The risk goes higher and higher'
Mr Langdon, from Baglan Moors in Port Talbot, said Iestyn, who has autism and attends Ysgol Hendrefelin, a special school in Bryncoch, is anxious about sitting next to other children on the school bus.
He said: "They're all in different classes, so that's a concern, but we don't know who he's sitting by. He texted us from the bus [on the second day of school] saying 'I'm going to have to sit next to someone because the bus has got too full'.
"Young people are being told to social distance but they're being sent on a bus like cattle with no social distancing measures.
"My concern is if I want to go to a local shopping centre by public transport I have got to adhere to social distancing and, if I don't, I will be fined. It's a breeding ground [for coronavirus] if you're not going to social distance on the bus."
Mr Langdon added: "It was obviously causing him anxiety and stressing him out."
"It's extremely contradictory in the fact that there's 14 other kids from different bubbles. If you do the maths, how many families are involved? The risk just goes higher and higher and higher."
'Complex but concerning'
Local authorities are responsible for school transport and Welsh Government guidance states social distancing should be implemented between learners, groups of learners and drivers "where capacity allows".
However, the guidance also says there is no requirement to maintain different contact groups, or bubbles, on school transport.
Nigel Thomas Hunt, a councillor who represents the Aberavon ward in Neath Port Talbot council, said there were "real concerns" about contact groups mixing on school buses.
He said: "I know it's very complex and it's going to be very difficult, but I'm really concerned.
"With Gary's son, it's caused a lot of anxiety, as it would a lot of children across Wales. I think it really highlights some of the complexities of coming back to life and opening schools up."
What does the council say?
A spokesman for Neath Port Talbot council said it was following Welsh Government guidance to reduce the risk of transmission while allowing learners to attend school.
He said: "Where social distancing is not possible, other systems of control have been implemented. Examples of these measures would be that vehicles are regularly cleaned and disinfected, windows are opened to allow ventilation and PPE (personal protective equipment) is worn by staff if they are in close contact with others.
"Furthermore, all secondary aged pupils have been issued with three reusable face coverings by the local authority and are required to wear them on home to school transport, including the route to and from Ysgol Hendrefelin.
"Understandably, it is an anxious time for us all and in particular for parents and pupils. We would strongly advise all pupils and parents to discuss their concerns with their teachers in order that anxieties are understood and allayed as far as possible."
The Welsh Government said: "We are working closely with local authorities, the Confederation of Passenger Transport and bus operators to ensure safe and accessible school transport.
"We recently announced £10m to help the bus industry get more passengers to school and college, building on previous funding commitments.
"We have published detailed guidance but will continue to work with local authorities and transport providers to address any remaining concerns they may have."