Coun Mair acknowledges the county council has a statutory obligation to deliver free school transport.
At present, national regulations state that all primary school pupils living two miles away from school qualify for free or heavily subsidised transport.
That limit is three miles with regard to secondary schools.
However, the council has no obligation to provide free or even subsidised transport for pupils age 16-plus to attend college.
Coun Mair claims the council’s annual budget for school transport is £20 million. However, he says implementing the national living wage will add another £5 million to the budget.
He added the criteria for free and subsidised transport was being looked at and that children living in ‘borderline locations’ to the mileage criteria could miss out.
He also said any changes to policy could limit the choice of schools for pupils of all ages.
Coun Mair said: “If a child wants to attend a school that isn’t closest to their home, they could have to start paying.
“This could have a big impact on grammar schools who often attract pupils from outside their catchment areas.
“However, the biggest impact could be on college students.
“There is no statutory right for the authority to pay for students over 16.
“This is where the biggest impact could come.
“Imagine a family with two teenagers at college. You could be talking almost £3,000 a year.”
At present, parents/carers have to make a contribution of £418-a-year for transport to and from college.
There are various dispensations for families on certain income levels, benefits - or with medical problems.
Coun Mair warned many parents would be unhappy if the current criteria is changed.
He said: “How many people have two or three thousand pounds just sat around?
“Or what about the parent of an 11-year-old girl who lives close to the two or three mile limit.
“She might well get free transport at the moment but if the criteria is tightened, then she would have to pay for a bus or walk to school - probably along unlit and unsafe routes where street lights are switched off and surfaces aren’t repaired.
“People will say I’m scare-mongering - or talking rubbish. But remember what happened with libraries. There is a legal obligation to provide library services but in some instances, the council just changed their names to community hubs - and shut them.”
County council leader Martin Hill says: “We have a legal duty to provide free transport for qualifying children up to the end of their compulsory schooling at the age 16 - if their nearest school is over three miles from their home address of course we will continue to meet this duty.
“The council also heavily subsidises transport for learners over age 16 to their sixth form or to a college, which we have no requirement to do.
“Very difficult decisions will need to be taken very soon about whether the council can continue to subsidise this at the same rate.
“However, the council is committed to protecting young people’s rights to access further education opportunities and will consult on any specific proposed changes.”